Ask the Experts - All Answers



by category

  1. What 2 constellations or clusters of stars can we see all year long?

  2. How can you make oil sink in water?

  3. What is the Discrete Fourier Transform?

  4. What are quantum numbers? And how many are there?

  5. How come the protons in the nucleus of an atom do not spin around like the electrons do?

  6. Could you please explain the general theory behind the sound that is produced when water falls on a hot surface?

  7. Does ozone occur naturally at ground level and is it safe to breathe?

  8. Would a newspaper bleaching in the sun be a physical or chemical change?

  9. How do you find an objects resonant frequency?

  10. Since antimatter is created when two matter particles are slammed together at high velocities, could the vice versa work and create matter?

  11. What is the particle structure of a flame?

  12. Is the earth's rotation slowing down?

  13. Is there any experimental proof that an electromagnetic wave has momentum?

  14. If Big Bang theory suggests that the universe started out as a homogeneous mass that spread uniformly in all directions, how did we get 'lumps' [stars, galaxies, etc] in the universe?

  15. In General Relitivity, Acceleration and Gravity is the same; So does that mean that when matter accelerates it emits gravitons as do a gravitational force does?

  16. In circular motion the body has constant speed but not constant velocity? Why?

  17. Currently,where are the Voyagers 1 and 2 space probes?

  18. What is the significance of uncertainty principle in the real world?

  19. Why don't the proton and the electron in a hydrogen atom collapse?

  20. How does Earth's Rotation relate to time taken by aircraft to reach from say India to the United States and back?

  21. A full can and an empty can are rolled down a ramp. What happens and why?

  22. Why is heavy water poisonous?

  23. Why is it dangerous for a person to stand near a very highly charged object?

  24. Which direction would a helium filled ballon go in an enclosed car that turns right, and why?

  25. Would it be easier to remove an electron from second level or the third level? Why?

  26. Is a drop of water from a dropper equal in volume to a drop of mercury from the same dropper?

  27. When carpet and a marble floor are at same room temperature, why does carpet feel warmer than a marble floor?

  28. In a series circuit with two or more bulbs, which bulb lights first when the circuit is closed?

  29. Why are left turns on a cycle easier than right? Also, when I run track I notice that everyone always runs counterclockwise.

  30. How does a Crookes Radiometer work?

  31. What is the physical explanation of the fact, that the electric field is zero inside a conductor?

  32. If an orbiting artificial satellite were to slow down, what would happen?

  33. Vacuum is a dielectric. Where does the impedance to charge flow come from?

  34. If you lit a flame in an oxygen atmosphere in space, what direction would the flame burn in?

  35. Please explain why do long rivers ( such as the Nile ) flow along serpentine paths rather than straight?

  36. What is a quantum dot?

  37. If heat rises, why is it so cold in the upper atmosphere?

  38. Is it possible that my computer crashes because of the cosmic radiation?

  39. What are the upper and lower limits for the mass of a neutron star? - and why?

  40. If the iceberg is sitting on the bottom of the ocean and NOT floating, would the water level rise as the ice melts?

  41. If the pressure at the bottom of the ocean is high, why is it so cold?

  42. If the Sun is supposed to be producing white light, why does the sun appear yellow to the eye instead of white?

  43. If the sun gives off UV rays, does a flame give off a small amount of UV rays as well? Or does the sun give off UV rays because it burns a certain element or chemical compound?

  44. If nothing can come out of the black hole, how come the x-rays can be emitted?

  45. What is plasma?

  46. How does gravity alter the trajectory of light?

  47. Why does the temperature remain constant as a pure substance undergoes a phase change, such as liquid to gas?

  48. Why is uranium fissionable and not, say, aluminum?

  49. I have read that gravity waves travel at the speed of light; does this mean that gravity waves are a part of the electromagnetic spectrum?

  50. How does night vision work?

  51. What are the light bullets (electromagnetic solitonss)? Do they contradict the Maxwell equations?

  52. Can you give me an example within a cartoon or a movie where the laws of physics are inaccurately displayed.

  53. Who was the Nobel Prize-winning American Physicist that is credited with determining the charge on the electron through his oil drop experiment?

  54. Why do we hear a hissing sound when we open a coke bottle?

  55. How does humidity effect the way that an airplane flies?

  56. What would a bubble of air or an air lens in water do to parallel incoming rays of light?

  57. What is the weight of 1 cubic foot of air?

  58. What is the difference between black hole singularity and big bang singularity?

  59. If you burn a piece of wood in a confined space would the weight of that space change?

  60. Is it possible to have a hollow sphere with a continuous north pole on the outside and a continuous south pole on the inside?

  61. What is the Zeeman effect?

  62. Some physicists see great potential in superstring theory, while others reject it. What is the alternative to superstring theory?

  63. How did Max Planck determine the planck length?

  64. What does salt do to water that raises the boiling temperature? Is it a chemical reaction?

  65. Why does firewood crackle when it is thrown in a fire?

  66. Exactly why does water cool down so much slower than it heats up?

  67. If I carve out a perfect sphere out of a bar magnet, how will it choose a north and a south pole?

  68. We know that fire needs oxygen in order to burn. Then how come stars continue to burn even though there is no oxygen in space?

  69. What is the minimum altitude from the equator needed to view the Earth as a whole?

  70. How do we know that the light from a distant, moving source has shifted from one part of the spectrum to another?

  71. Foods can be sterlised by passing gamma radiation through it. Why is it still safe to eat? Won't it become radioactive?

  72. From what I understand, Planck time is the amount of time it takes a photon to move Planck length, but what is Planck length and what is it based on?

  73. In the EPR paradox by Einstein, is there any information transfer in the process? Is the information different from what we have in a message?

  74. Why do military aircraft often fly in formation and is it in any way related to the reason birds fly in formation (conservation of energy)?

  75. Shortening a guitar string to one-third its initial length will change its natural frequency by what factor?

  76. Where can i find einstein's original papers on the internet?

  77. If most of the large galaxies have black holes at the center, why do photos show a very bright spot instead of a black spot?

  78. What would happen to a balloon if it was blown up in a classroom and then taken to the top of Mount Everest? What would happen when it came back down?

  79. If fire needs oxygen of burn, how come it is used in H2O to put out fire?

  80. If an airplane wing provides lift (an airfoil), how does a plane fly upside down?

  81. Is the popular belief that 100° steam is more injurious to the skin than boiling water just a wives tale?

  82. Why is it that the lunar disk precisely covers the solar disk during a solar eclipse? Is it just an extraordinary coincidence?

  83. How does the atomic clock change to daylight savings does stop and than catch up or does it go forward?

  84. How can one measure the age of the universe?

  85. How did the Atom obtain it's name?

  86. How hot is it at the center of the Earth?

  87. What is the quantum theory of gravity?

  88. Is it possible for electrons to quantum tunnel through charged aluminum foil?

  89. Would Jupiter float in a body of water?

  90. They say that the safest place to be when a bomb explodes is right on top of it, is that true?

  91. If you lived on the Moon, would you see the sun rise and set? how about the earth?

  92. Could someone please explain to me the difference between a Type 1 Nova, and a Supernova?

  93. How astronomers know that our galaxy is not centre of universe?

  94. What are Kepler's laws of motion and what exactly do they mean?

  95. Why is Pluto so different from the other planets?

  96. Is there any practical proof of time dialation on atomic particles?

  97. How high can a (commercial or military) jet aircraft go?

  98. If we have not yet discovered a method of seperating quarks from each other in protons and neutrons, how did scientists discover that protons and neutrons were composed of quarks?

  99. How long did radio commands take to travel from the Earth to Voyager as it passed Neptune?

  100. Have gluons actually been detected, and if they have, how?

  101. How does a laser cool something, as in producing a Bose-Einstein condensate?

  102. Is the law of conservation of energy violated for a short or long period of time and can it be experimentally observed?

  103. How did the earth come to have a molten iron core?

  104. Why can you not get sunburned behind a glass?

  105. Why the law of momentum conservation is not violated when a ball rolls down a hill and gains momentum?

  106. Is the most heat lost by the means of conduction, convection or radiation?

  107. What is the hottest part of the Sun?

  108. Would I receive more energy from a solar cell if I were to filter everything but UltraViolet light? Or do you get more energy from all wavelengths added together?

  109. What is the smallest amount of time?

  110. If I were able to set a flashlight out in the middle of space and turned it on, would it move?

  111. How can you differentiate an element from a compound?

  112. What is the difference between paramagnetism and ferromagnetism?

  113. How come x-rays can escape from a black hole when visible light can not?

  114. Is there really a planet X?

  115. Why do colors illuminated with moonlight lack color?

  116. If you stand at the bottom of a well and look up at the entrance is it possible to see stars in daylight?

  117. What is it about lead that makes it useful in radiation shielding?

  118. What is the method used to find out the distance of Andromeda galaxy from us?

  119. Why do most of the planets orbit the sun fairly on the same plane?

  120. Why can't we put our hands through a table? (Does it have to do with density and/or matter?)

  121. Why is it dangerous to look at the solar eclipse directly specially at that moment?

  122. Why are all stars yellow?

  123. Is it possible to exploit the magnetic field of Earth to obtain electricity?

  124. How does ice form on a window pane if there is no water?

  125. If an aircraft travelled in the opposite direction to the earth so that the earth had turned once would the occupants of the plane be considered as having travelled backwards in time?

  126. When a mercury thermometer is immersed in a hot liquid, the mercury level goes down at first and then goes up. Why?

  127. How can people walk on burning coal and not burn themselves?

  128. How do you keep warm in an igloo? What's the underlying Physics behind it?

  129. What do external forces have to do with equilibrium?

  130. Can you boil water without heat? Why and how does it occur?

  131. What is depleted plutonium and how radioactive is it?

  132. If oxygen is needed for fires to burn and hydrogen is a highly explosive gas, why does water not explode when exposed to fire?

  133. What is the basic difference between the Pauli Exclusion Principle and the Heisenberg Uncertainty Principle?

  134. Does cold temperature affect the elasticity of a rubber band?

  135. What is an Eddy Current?

  136. How many times should all the people in the Northern-Hemisphere should jump simultaneously into the air to alter the Earth's orbit by 1 m?

  137. Which is larger, the proton or the neutron?

  138. What causes different colors in flames?

  139. How is a plane protected from Lightning strikes?

  140. What is material dispersion? In which way it is helpful in optical communication?

  141. I was taught in school that the Sun DOES NOT MOVE at all. But it does move around the galaxy at the speed at 250km/s. And does it spin? Please give me a bigger picture to look at.

  142. How are the protons and neutrons held together in a nucleus?

  143. Does time pass faster or slower close to the black hole?

  144. How is Mach related to temperature of the air? How does a sudden change of temperature affects the propulsion of a jet engine?

  145. What is FET?

  146. When a car is driving up a hill, is the friction between the tires and the ground static friction or kinetic friction?

  147. Which is larger - a quark or an electron?

  148. How do quartz watches work?

  149. I heard that the speed of light is the same to any observer, no matter how fast he moves, and that the faster you move, speed of light is still the same relative to you. Is this true, and why?

  150. I was told that lower frequency sound waves (like from a bass guitar) travel lower to the ground that higher frequencies. Is this true?

  151. Would it be possible to see the rings of Saturn with a telescope? How can one find out what years the rings are visible?

  152. What are the six simple machines used in the study of physics?

  153. If a car is traveling with a helium-filled balloon in the back seat, and the car suddenly stops, what happens to the balloon?

  154. Is there a conversion factor between the radiation units Curie and Roentgen?

  155. If you had an iceberg in a bathtub and it melted, what would happen to the water level in the bathtub, and why?

  156. What is the Andromeda Galaxy distance from the Sun?

  157. What is nanotechnology and why is it such a buzz in the computer industry?

  158. What is the difference between atomic physics and nuclear physics?

  159. How many miles does the Earth travel in space each day?

  160. My son is taking complex numbers in high school, and he is asking 'What are these good for?' I know they are used in electromagnetic calculations, but how?

  161. Is stainless steel magnetic? Does it depend on the amount of chromium, or nickel alloy?

  162. Has anyone ever calculated how far we are from the point of the big bang?

  163. What is the electric field due to an infinite sheet of charge?

  164. What are some examples of cohesion and adhesion?

  165. How did thermal blackbody radiation spectrum not fit classical physics and what was done about it?

  166. What is the most useful type of mathematics for physics?

  167. Names of stars usually start with letters NC and are followed by numbers. What does NC stand for and why are they named as such?

  168. Is the 3rd law of thermodynamics valid even for objects smaller than atoms?

  169. How is the measurement Watts related to temperature in terms of energy?

  170. Why does the night-sky in spite of the presence of countless stars appear dark?

  171. What is the physics involved in skydiving?

  172. How can one prove that the world is round?

  173. Why does the nuclear fusion reaction yield more energy than the nuclear fission reaction?

  174. How are quasars related to black holes?

  175. How do liquid crystal displays (LCDs) work?

  176. Do all solids have a melting point? For example, is there a point when a tree, a piece of paper, or other carbon based solid becomes a liquid?

  177. Is there such a thing as a 3d fractal?

  178. What are the differences between jet airplanes and rockets?

  179. What is a quantum well?

  180. What are eddy currents and how do eddy current brakes work?

  181. How does a hydraulic jack work?

  182. What is meant by background radiation?

  183. Why does space shuttle fly up with its belly upward and its back downward (i.e., astronauts sitting upside down)?

  184. If a spacecraft was fitted with a laser would the photons emitted push the craft upwards as in the solar sail or beamed energy propulsion concepts?

  185. If Bernoulli's equation is true, then wouldn't the passengers in a car die of suffication (because of the lower pressure system outside of the car creating a vacuum inside the car) if they had their windows down while driving?

  186. Why is it that a magnet distorts the image from a television or computer monitor (even though photons are uncharged)?

  187. What are Eigen Values?

  188. I have often read that scientists are searching for the next prime number. My question is why? What use is it? How can knowing the next highest prime number be of any benefit?

  189. What is Boyle's law?

  190. What is the difference between resistance and impedance?

  191. How can a potato be used to light a lightbulb?

  192. Is there a day and night on the moon?

  193. How does sunblock block out UVa and UVb rays?

  194. Is it possible to place a satellite in geostationary orbit over the north pole?

  195. Is there any material that can block a magnetic force? Specifically does lead block magnetic fields?

  196. What time is it when standing on the North Pole?

  197. At what point does a black hole stop sucking in mass and explode creating a new time/space continuum?

  198. Is it possible to slow light down?

  199. Will there be any change in water level/height of floating part of the boat if stones are dropped into the pond from a floating boat?

  200. If dimples on a golf ball make it travel further then why don't they use dimples on aircraft?

  201. Why the masses of proton and neutron are not exactly equal?

  202. According to QM, a radioactive atom will decay randomly. But, how many atoms does it take to enforce a predictable half life? And why?

  203. What is the partial pressure of oxygen in a commercial airplane at 30,000 feet?

  204. In numerous photos and films of nuclear explosions, there appear to be vertical streamers along side the fire ball/mushroom cloud. What are they?

  205. What is a light-year and how long is 1 light-year?

  206. What are the fundamental particles that make up a nucleus?

  207. How were pulsars discovered?

  208. Will the earth's orbit around the sun eventually decay as a satellites orbit decays around earth orbit?

  209. How many astronomical units are in a light year?

  210. If a visible laser on the earth is shone on the moon and the beam is moved along the surface, could the beam spot on the moon be made to travel faster than the speed of light?

  211. What exactly is the purpose of the spoiler on a car and how does it work?

  212. What would happen if Earth lost it's tilt and just stood vertical?

  213. What happens to the charged particles which came from the sun after they hit the atmosphere of the earth?

  214. Why is liquid oxygen magnetic?

  215. Why does the north star always point north?

  216. If I am on a merry-go-round with a friend, and the friend is closer to center than I am, are they going faster then I am?

  217. What is it aliasing? When it occurs?

  218. I am curious as to exactly when scientists found out that space is a vacuum and not made up of ether? What year was this and who is credited with the discovery?

  219. What is the magnetocaloric effect and what materials exhibit this effect the most?

  220. Is there a scientific way of estimating how much time a given mass of ice will take to melt in a controlled ambient temperature?

  221. Why do colors illuminated with moonlight lack color?

  222. Do all galaxies have black holes at their centers? If not, what provides the gravity to hold the galaxy together?

  223. If there is no gravity in space, how do astronauts digest their food?

  224. What is the hardest rock and what is its compressive strength (PSI)?

  225. Is it true that a duck's quack doesn't echo? If so, why?

  226. If oxygen feeds fire and hydrogen is explosive, then why isn't water combustible?

  227. Why don't photons collide with each other when traveling towards each other?

  228. What is the physics involved with breaking glass with your voice?

  229. Why do rubber bands contract when heated instead of expanding?

  230. Is it true that the further a planet is from the Sun, the faster it rotates around itself?

  231. If neutrinos both move at the speed of light and also have rest mass, what bearing does this have on relativity?

  232. Can a laser be used as an electrical conductor between two points that are not in physical contact? If so, is there a distance limitation?

  233. Will a lake freeze faster on a windy day than a calm day?

  234. Why does your hand look funny when you move it fast in front of the tv or computer screen?

  235. Do magnets ever lose their magnetism?

  236. What is Huygen's Principle?

  237. What is a short circuit?

  238. Does the temperature of a football (or baseball, soccer ball, etc) affect how far it will travel when kicked/hit?

  239. Why are there no tides in rivers and lakes?

  240. Why is petrol/oil in water colorful?

  241. When a flame comes out of a lighter on earth, it points up; which way would it point in a zero g environment?

  242. What is meant by the theory that the sun is a third generation star?

  243. What is the difference between laminar and turbulent flow?

  244. Why is an apple pies sauce always hotter than the pastry even though they have been cooked on the same heat?

  245. How is force related to momentum?

  246. Do wires degenerate when electric current is passed through them? I mean, do they lose matter after continued use?

  247. What are the odds of me experiencing Quantum Tunneling?

  248. What is a tensor and can any examples of their use be given?

  249. What are fractals?

  250. If nothing can travel faster then the speed of light, how does one explain Cerenkov Radiation?

  251. Why isn't radar used underwater instead of sonar if radio waves are faster than sound waves?

  252. What's the Pauli-exclusion Principle?

  253. Why does air get colder as it expands?

  254. Discounting mountains, valleys, and other gross surface features, is there any place on Earth from which the Moon is not visible at all?

  255. Why do asteroids leave the asteroid belt in the first place?

  256. How does a solar cell work? Is it possible to create one using simple lab apparatus?

  257. Why does ice melt faster in water( at room temp.) than in air?

  258. Why does the passenger side window on my car state 'objects in mirror are closer than they appear?

  259. What would be the force required to accelerate 1 gram to 20% of the speed of light?

  260. What is the physics involved in snowboarding?

  261. How much math is needed to become an Astronomer? What kinds of math must you know?

  262. Has the speed of propagation of a magnetic force field been measured? If so what is it?

  263. Is it possible for a single photon to produce diffraction pattern?

  264. Why is it impossible to pump water from very deep in the ground with a surface pump?

  265. How is the frequency of a photon/light measured? How long does such a measurement take?

  266. If you pour soda pop into a glass at room temperature is fizzes, but if you pour it into ice it fizzes a lot. Though carbon dioxide is more soluble in the pop at low temperature, why does it fizz more with the ice?

  267. How can the electric potential in the exact center of two equal but opposite charges be zero, but the electric field be non zero?

  268. If a planet was at a distance of 3.6 parsecs, how many light years away is this planet?

  269. How does a sailboat move upwind?

  270. What is the chaos theory?

  271. Why is that electrons radiate electromagnetic energy when they are accelerated?

  272. What are the various colors of lasers we have today?

  273. How do diffraction gratings tell us information about distant stars and galaxies?

  274. Is there any practical proof for time dilation?

  275. Is there a relationship between electrical conductivity and thermal conductivity?

  276. I was wondering if there is a table that shows the volume vs temperature for Mercury (Hg)?

  277. How does a transistor work?

  278. What will be the fate of our moon? Will it remain in a stable orbit, crash back into Earth or drift off into space?

  279. What is the mirage effect?

  280. How does a transformer work?

  281. How do you prove a number, like e or pi, to be transcendental?

  282. Why is Venus the hottest planet even though Mercury is closer to the sun?

  283. What is the pH of water?

  284. Why does a golf ball slice or draw? What is the difference in the flight of a golf ball hit with back-spin and one hit with top-spin?

  285. Does the sun move at all?

  286. Can you make an ultra-violet light source by painting a regular incandescent light bulb with black paint?

  287. How much heat per hour do humans dissipate?

  288. What is the volume of Earth?

  289. I noticed that pouring hot coffee into cold cream results in a higher final beverage temperature than pouring the cold cream into the hot coffee. Can you explain the physical principle behind this observation?

  290. We are having a party at work, we want to use dry ice as an effect, can we put it into our punch and then drink it? Is it safe?

  291. When annihilation occurs what happens with the charge of the interacting particles?

  292. I have a clear plastic ball with some electronics inside. When bounced, LEDs flash on and off. I suspect that it contains a piezoelectric crystal and I would love to know how it operates.

  293. Who invented the transistor?

  294. If I am standing on a mountain, Am I going faster than someone at sea level? If so, is my day shorter or will the higher vantage point of the horizon allow my day to seem longer?

  295. If lightning strikes an airborne aircraft, are the occupants affected? Why or why not?

  296. How does a cat land on its legs when dropped?

  297. There are two persons in a plane which is traveling at a speed greater than the speed of sound. If one of them talks, will the other hear it?

  298. What is the equivalent of 1 Lux unit in Watts?

  299. Who is the inventor of television?

  300. What is the nature of the dense fog that forms over the surface of liquid nitrogen?

  301. Is there any gravitational force between two photons?

  302. Why an electric bulb needs to be vacuumed? Can we light up a bulb in the space without enclosing in the glass bulb?

  303. Where does the dark energy / matter come from?

  304. How is carbon dating done?

  305. What is an electronic ark?

  306. What is the Mobius Strip?

  307. How do sea navigators measure their ships speed?

  308. Why is it that on a cold day sky seems more blue? Is there a direct connection between temperature and the 'blueness' of the sky?

  309. How many oscillations does a caesium atomic clock make in a day?

  310. If a spherical mirror is immersed in water, does its focal length change?

  311. How do evaporative coolers work?

  312. Is there a definite end to the electromagnetic spectrum?

  313. What is the zeta function?

  314. What are the advantages of ABS braking systems compared to other hydraulic braking systems?

  315. Do sub-atomic particles obey Newtons Laws of motion?

  316. How fast (ie: clockspeed in Hz) can a single processor in a computer be? The highest I've read is 4 GHz. What's the limit?

  317. Is it purely coincidental that the moon rotates on its axis in synch with its revolution around the Earth, keeping the same face always pointed toward us?

  318. Assume there is an ice cube in a glass of water. When the ice cube melts, will the water level have risen, fallen, or remained the same? Why?

  319. Is there a precise formula giving the increase in mass due an increase in velocity as described by relativity?

  320. Why are there usually more neutrons than protons in a heavy element? Has Pauli's exclusions principle got anything to do with it?

  321. Which is most likely to burn you? Microwaves, gamma rays or x rays?

  322. Why are jet engines' and rocket engines' tails shaped differently, one gets narrower as the other gets wider?

  323. Are there any galaxies that have a blue-shift?

  324. Can a dummy load be switched on to overload the outside power lines, raise their temperature and melt the accumulated ice away?

  325. I know for a fact that a moving charge can produce a magnetic field. But I'm curious if a moving magnetic field produce a charge?

  326. How long does it take for a radio signal to go from Earth to Mars?

  327. What will happen to the gas at absolute zero temperature (0 K)?

  328. How do microwave ovens work and are they harmful in any way?

  329. If you have a magnet inside a box made of a superconducting material (in its superconducting state), would there be any magnetic field around the exterior?

  330. What is CP violation and how does it explain the fact that matter outnumbers antimatter in the universe?

  331. What is a fuel-cell and how does it work?

  332. Where in the United States is the force of gravity the strongest?

  333. What is the physical meaning of a commutator in quantum mechanics?

  334. What is the origin of the fact that a circle has 360 degrees? Why not 720 or 270?

  335. What is the coherence length? What is the coherence time?

  336. How much does water expand when it's frozen?

  337. How fast a person must be going in a car to make a red light appear green?

  338. What is correct: To mention temperature in deg K (°K) or in just K?

  339. What happens at the ends of the electromagnetic spectrum? Do the wavelengths continue to get shorter and longer or is there some ultimate limit?

  340. How much Hydrogen can be extracted from a gallon of water? Is there any reason why a fuel cell powered aquatic vehicle (boat, submarine) could not supplement the Hydrogen supplies on-board with Hydrogen extracted from sea water, thus extending their range?

  341. How many known elements are there now?

  342. What is heavy water?

  343. Does seismic activity on Mauna Kea effect the operation of the telescopes there?

  344. Do the moon and sun appear larger on the horizon, or is it just me?

  345. Can energy be converted back into mass?

  346. What kind of forces hold the protons and neutrons together in the nucleus?

  347. Why does the stream of water from a faucet become narrower as it falls?

  348. What is the difference between NMR, MRI and ESR?

  349. Other than the U.S., what other country still uses the old English System of Units?

  350. Is it true that ice skaters actually slide on water instead of ice? Is the pressure from the blade on the ice sufficient to melt ice into water?

  351. How night vision goggles work?

  352. Where are the Pioneer and Voyager space probes? Are they still operating? Is anybody listening to them?

  353. Since magnetic forces can do no work, what force IS doing the work when a bar magnet causes a paper clip to jump off a table and stick to the magnet?

  354. How do we see things upright if the image formed on the retina in our eye is an inverted one?

  355. Does gravity have a speed?

  356. How does a boomerang work?

  357. What exactly is a dBm and how would you measure it?

  358. What are Free Radicals?

  359. Did they really split the electron?

  360. How did planet Neptune get its name?

  361. How is light formed in a light bulb?

  362. Can you hit a golfball into orbit on the moon?

  363. When you rub your finger along the rim of a glass, it resonates, why is this? Also, why does the pitch of this sound get lower when you add water to the glass?

  364. My student was messing around with the bunsen burner when he noticed the following. He had put a wire gauze on top of the burner before turning the gas on. When he used the lighter on the bottom portion i.e. below the wire gauze, a flame was only visible at that portion but not above the wire gauze. When he used the lighter on the portion above the wire gauze, the flame only appeared on the top portion but not the bottom portion! Why?

  365. Approximately how many atoms are in a grain of salt?

  366. Adding carbon to steel makes it harder and stronger. Is this true for all metals? Could you add carbon to titanium or vanadium to make them even harder and stronger?

  367. Why is the gap in the ozon layer the worst above Antartica, given that the highest emission of CFK's happens in the Northern Hemisphere?

  368. What is the Pascal's law?

  369. What causes high tide and low tide and why?

  370. The index of refraction for liquid water is 1.33. What is the index of refraction for ice? The physical density is changed, but is the optical density changed as well?

  371. If the size of the universe is infinite and the speed of light is constant, are there places light has not reached?

  372. I have heard there is only one component of the atom momentum quantized, (Lx, Ly, Lz) then, does it have an orientation in space?

  373. Do molecules have colours? What about electrons, protons and neutrons?

  374. I have noticed that many Einstein quotes mention his belief in 'truth and beauty' - I was wondering, is it purely coincidental that two of the six quarks are also named truth and beauty?

  375. Given the First Law of Thermodynamics: that you can't get something from nothing. Where did all the stuff in the universe come from and how is it still a law if it was once broken?

  376. How electric guitar pick-ups work?

  377. What is the difference between nuclear fusion and cold fusion?

  378. What is the Schrodinger equation, and how is it used?

  379. What is the easiest way to calculate the earth's athmoshpere's weight?

  380. What is the difference between atomic and nuclear physics?

  381. What is temperature? Is temperature a measure of the vibrations of matter? If so isn't it related to kinetic energy and therefore not a base quantity?

  382. What would you consider to be the 5 or 10 most important/fundamental questions physicists are trying to answer currently?

  383. Where is mercury found in the world?

  384. Why are there no stars when the astronauts take pictures from space?

  385. What makes a paper clip float?

  386. What is the amount of energy given off when an electron and a positron anhilalate?

  387. How can I make an electrical battery at home?

  388. How is time a function of the fabric of nature, and not perception only?

  389. How does one 'liquify' helium? How is it cooled enough to become a liquid?

  390. Where do I find a list of metals with their heat expansion index?

  391. What are the physics involved in throwing a frisbee? And why its specific shape?

  392. How was the mass of a proton determined?

  393. If neutrinos have mass, as my physicist nephew from Fermilab says is now the consensus, how can one explain the virtual simultaneous arrival of neutrinos and photons from the Supernove1987A in a Magellanic cloud about 300,000 light years away?

  394. I have heard that humans have a wavelength. Is this true?

  395. How can you boil a liquid without heating it? Why is this possible?

  396. What is the difference between the inertial and gravitational mass?

  397. What is a Higgs Particle?

  398. What are liquid crystals made of?

  399. Considering only temperature and disrespecting the rest, would I feel cold or hot with my hand in the vacuum?

  400. With such limited resources of his time, how did Avogadro come up with his number (the number of molecules in a mole of gas)?

  401. What is the wavelength of UVa, UVb, and UVc light measured in nanometers, and frequency (in Hz)?

  402. What is the densest thing on Earth?

  403. Why the planets are not twinkling, while the stars are?

  404. How does an atomic clock work?

  405. What is the basic difference between Astrophysics and Astronomy?

  406. I heard that an electron moving in a certain orbital is actually perpetual mobile - is this true?

  407. Which planet rotates so fast that its day is only 10 hours long?

  408. What is a one way mirror and how does it work?

  409. What is a Bose-Einstein condensate?

  410. Photons are Bosons, so why don't they make Bose-Einstein-Condensation?

  411. Is it possible to make a perfect vacuum?

  412. If you shoot a laser into a thunderstorm will the beam act as a lightning rod due to the ionization of the air by the laser beam?

  413. Do gyroscopic forces from the wheels make any significant contribution to the rideability of a bicycle?

  414. What is the Humidex formula used to find subjective temperature as a function of both measured temperature and relative humidity?

  415. What is a quasar and what does it have to do with a black hole?

  416. How do adhesives (i.e superglue) not stick to their container?

  417. Which of these 3 sports will be the hardest or the easiest to play on the moon? Basketball, Soccer or Football?

  418. If it was possible to travel faster then the speed of light, would time reverse itself (like backwards time travel) or just not exist?

  419. How can water co-exist at three phases (solid, liquid and gas)?

  420. What is Planck length? What is Planck time?

  421. What is a simple defintion of the laws of thermodynamics?

  422. Why does the red color appear at the horizon during sunset?

  423. If an electron were increased to the size of an apple, how big, proportionately, would a human being be?

  424. How fast would the Earth have to rotate so that it would neutralize gravity?

  425. What is the ultimate fate of our sun?

  426. What are Lambert's Laws?

  427. What is a neutrino?

  428. Are coriolis forces strong enough to cause an open basin of water to create whirlpools moving in opposite directions when the basin is transported 20 feet either side of the equator? I saw this demonstrated in Kenya (for money), but I wonder if there wasn't a trick.

  429. How many smoke detectors would it require to pose a definite health hazard in an average 3 bedroom home of approximately 2000 sq.ft. and under what conditions? (These being equipped with Americium 241)

  430. I am thinking about building a 1 or 2 man blimp. How many cubic feet of helium is required to lift, say, 300 or 500 pounds?

  431. How are solar sails possible? If photons have no mass, how can they push on something?

  432. What happens when a tablecloth is pulled out from underneath a table setting, and everything on the table stays put?

  433. What force in the universe is the strongest or the most powerful?

  434. What does the term 'strangeness' refer to?

  435. We talk of positively and negatively charged particles. But what actually is a charge, what is the property of charge caused by?

  436. Since oppositely charged particles attract, and gravity is a phenomenon common to all particles, how come the electron is not 'sucked' into the nucleus?

  437. Why do Foghorns always have very low pitches? Do they have high or low amplitude?

  438. What are Feynman diagrams? Could you give good bibliography about QED?

  439. When matter is dragged into a black hole, where does it go or what happens to it?

  440. The Second Law of Thermodynamics states that the universe tends toward high entropy. If so, what happens when there is nothing left to be disordered? How can matter be constant?

  441. Say you have a twin, and you go off into space, traveling near the speed of light, when you return, will your twin have aged more?

  442. Is there a formula to calculate the triple point of a substance?

  443. Is time quantized?

  444. How can something have a negative mass, and what does that mean?

  445. What is the angular velocity of the Earth around the Sun? How do we get it?

  446. How long does it take for moonlight to reach the earth?

  447. What is cosmic radiation? Is it dangerous?

  448. How does a star become a supernova or a black hole? How does the star decide which one to turn into?

  449. How was the critical density of the universe calculated?

  450. What is singularity and why do all laws of physics break down at singularity?

  451. The Nasa newsletters state sun spot activity is increasing from expected count. What is the cause for excessive sun spot activity?

  452. Now that the universe is proven flat, what implications does it have on the special theory of relativity, particularly the gravitational aspect?

  453. I heard that 'bosons' are particles made from a quark and an anti-quark. Is this true? If it is, then how come they do not to annihilate each other?

  454. If there is anti-matter, couldn't there be anti-energy?

  455. How does a dunking ducky work?

  456. Why the lines of force in an electric field start at the +ve charge and terminate at the -ve charge?

  457. What is the difference between a physical change and a chemical change?

  458. Why are the colors of the sky at sunrise different at sunset?

  459. If nothing sticks to Teflon, how does it stick to the pan?

  460. What is a delocalized electron?

  461. How can I prove that the earth rotates around the sun?

  462. What is the speed of light in parsecs per year? What is a parsec?

  463. What is the Astronomical Unit?

  464. What is dry ice & Why does it steam when wet?

  465. How could you direct the laser towards the transparent tank full of water so that 100% of the laser light was reflected?

  466. Why is it easier to accelerate an electron to a speed that is close to the speed of light, compared to accelerating a proton to the same speed?

  467. Where can I find information on the average temperature of a cutting torch when it is used to cut steel?

  468. Is there any experimental data supporting the existence of gravitons? If there is, how fast do these wave/particles travel? Are they similar to photons?

  469. Can sounds actually break glass? If so, is there a special frequency or decibel level needed?

  470. If the speed of light were infinitely large, would the effects of time dilation and length contractions be observable?

  471. Does the universe have a total angular momentum?

  472. If both friction and air resistance were eliminated from acting on the swinging pendulum, would gravity act on the pendulum to slow it down and eventually stop?

  473. Why are sunsets red?

  474. What causes the high-frequency, ascending-pitch sound coming from a camera's flash unit when charging.

  475. Lets just say a huge asteroid hits the earth at the right speed and with the right amount of force and stops it's orbit around the sun. How long would it take for the earth to plummet into the sun?

  476. Is there any way to see ultra violet light, or make it?

  477. If I know the diameter of a balloon can I find it's volume?

  478. Where does the constant humming sound come from in transformers?

  479. On the atomic level, there is some free space between the electrons and nucleus of atoms (and between the protons and neutrons in the nucleus itself). What 'material' fills these spaces? Dark matter?

  480. If space is a vacuum, then how do space capsule's retrorockets steer?

  481. By what method is the size (or volume) of the universe at the moment of the big bang (or shortly thereafter) determined? Related to this, how is the size of a black hole determined?

  482. When high velocity particles travel faster than the speed of light in a medium they create a blue flash. This is called Cerenkov Radiation, why does this happen and why is it blue?

  483. Why is there resistance in wires, and when you vary things like the length of the wire, why does the resistance change?

  484. Why does light slow down when entering a prism but speed up when it exits? Where does it get the energy to increase it's velocity?

  485. What are we going to be able to see on may 5th. when all planet are in a line, if the clouds don't block us?

  486. If two lasers 1 mile apart and facing each other emitted a pulse of light at the same time surely the relative velocity between these 2 pulses of light would be 2c (c=speed of light). I was under the impression that nothing could exceed the speed of light so what is the true relative velocity between the 2 pulses?

  487. I heard that when international space station completed it could be seen by naked eye on the earth. Is this correct?

  488. Does the entropy of a closed system always increase, or could it possibly decrease?

  489. Do you get wetter if you run or walk in the rain?

  490. Why are reflected images seen more easily at night in a window from inside of the house, whereas during the day they are not?

  491. What is meant when one says that the temperature of the cosmic background radiation is 3K?

  492. Is our moon's gravitational field strong enough to retain a gaseous envelope and is there a gas with a sufficiently high molecular weight that could be used to create an 'atmosphere' for our moon?

  493. I heard from a friend recently that a new 'type' of matter has been detected at CERN: neutralinos. Is that true?

  494. A stationary van is filled with 1 tone of bees sitting down. Is it true that the overall weight of the van is the same if bees are flying instead of sitting?

  495. Could you explain van der Waals' forces to me, and their role in why energy is needed to vaporize water?

  496. Books say that heat transfer in an adiabatic process is equal to 0. How can this be if there is a change in temperature?

  497. Assuming the probability of obtaining heads in coin flip is exactly fifty percent, why should a test group of a ten flips produce less accurate results than one of one million flips?

  498. If you hover any distance above the earth (in a helicopter, for example) for a day or so, why aren't you and the helicopter occupants on the other side of the world if the Earth is going through its normal revolution?

  499. Could a circular space station simulate the Earth's gravity by spinning at a certain velocity? (I have seen something like this in A.C. Clarke's 2001)

  500. I am curious as to what causes the Earth's spin, and why does the Moon not spin?

  501. As an engineer, I know that friction does not depend upon surface area. As a car nut, I know that wider tires have better traction. How do you explain this contradiction?

  502. I am 11 yrs old and soon to be going to Magic Mountain to ride a roller coaster for the first time. My Dad says that I really don't need a safety harness when the roller coaster goes upside-down because centrifugal force will hold me in. Is this true?

  503. What experiment or phenomena proved that light was bent by gravity?

  504. Which is the lowest temperature known in nature (not in laboratory)?

  505. Which is heavier, wet or dry sand?

  506. What is the difference between the dietary calorie and the physical calorie? Is there a relation between the two?

  507. I run a projection booth at a local cinema. My machines run on DC current and the static electricity generated is wreaking havoc with the polyester base prints.How can I eliminate the static electricity from my booth?

  508. How does one electron go through two slits at the same time? In Young's Double-Slit experiment Hawking, Feynman and Brian Greenes ay that one electron goes through both slits at the same time.

  509. The tires of airplanes (at least the big ones) are inflated by nitrogen (instead of air). Why is this done?

  510. Why isn't the electron considered a black hole? It does have mass and its radius is infinitely small, isn't it?

  511. What is the difference between cathode rays and beta rays since both are basically electrons?

  512. I'm an actor playing the role of a balloonist and I want to be able to explain in scientific terms why helium and hydrogen make balloons rise.

  513. How are the rings of planets formed and what are they made out of?

  514. Atmospheric pressure is supposed to be very large. Then why is it that we, along with everything else on the earth, do not get crushed under this tremendous pressure?

  515. What is the significance of the number 137 in physics?

  516. Why is it that when you put your finger over the tip of a hose the water shoots out farther?

  517. Why does dispersion take place when light is passed through prism and not through glass slab?

  518. When the planets in our Solar System are in a line on 5 May 2000, will there be any reason for concern on Earth?

  519. What causes interference in reception in car radios?

  520. What exactly is the heat death of the universe and where can I find out more?

  521. My science data book says that the mass of a photon is zero. But how can photon exert radiation pressure, as it occurs in the sun?

  522. What is the name for a phenomenon where the presence of the observer changes the nature of the observed?

  523. What experiments are there to prove Absolute Zero? Who discovered it and how?

  524. Does a car use the same amount of gas traveling a given distance at 60 mph than it does traveling the same distance at 10 mph (or any other speed)? And if so, does a person burn the same amount of calories walking a given distance as running it?

  525. How does a Faraday Cage work? or, Why can a satellite dish have holes in it?

  526. If gamma rays can travel through walls, and radio waves can travel through walls, and they are on opposite ends of the electromagnetic spectrum, then why can't light travel through walls which is right in the middle of the spectrum?

  527. How is the 'STERADIAN' defined and how is it used?

  528. Is there any device that has, for a moment or so, zero momentum and possess kinetic energy?

  529. How are we able to determine the composition of our orbiting planets?

  530. I read that plasma is the fourth state of matter. In the same book, it stated that plasma was (basically) shattered particles, using fire as an example. Is this true?

  531. How can you measure the mass of the Earth or any other planet?

  532. If you're in a car traveling at the speed of light and you turn your headlights on, does anything happen?

  533. What is a tensor?

  534. Is the rotation of the earth considered the initial kinetic energy for a rocket before take-off?

  535. Would the current of a circuit consisting of a power source and a resistor affect the rate at which the resistor can heat water? If so, why?

  536. What are the frequencies of musical notes like G and G(cardinal) in k-hertz?

  537. Theoretically would light infinately bounce, in a room made of perfect mirrors?

  538. Does pure water reach its boiling point at a higher or lower temperature than Salted Water? and does the same apply to water saturated with sugar?

  539. How is aurora borealis created and why does it occur at the north and south pole?

  540. What is rest mass? How to explain it especially to the high school students?

  541. Why is there no colour spectrum at the sub-atomic level? Or is there?

  542. In a matter-antimatter reaction, is all the material converted into energy? If not, what is the efficiency of the reaction?

  543. What is escape velocity?

  544. What is the density of water?

  545. Is it easier for an airplane to travel East to West or West to East?

  546. Suppose 2 sinusoidal waves undergo totally destructive interference. This results in wave with zero amplitude (and hence zero intensity). What happens to the energy associated with wave (1) and wave (2)?

  547. In rotational motion, when the radius is decreased, does velocity increase or decrease?

  548. I have found a photo of a famous scientist by the last name of Cronin. For what was he famous?

  549. Are there any laws stating that time must flow in a constant stream (i.e. moments in unbroken succession)?

  550. I was working graveyard shift at a convenience store. A gallon jug of water suddenly exploded on a shelf in the office. The temperature was controlled, eight other gallons rested on the same shelf. What happened? Is this evidence of atoms having a finite life?

  551. I often get confused between the terms centrifugal force and centripetal force could you please enlighten me?

  552. If you left the refrigerator door open, what would happen to the room temperature and why?

  553. What is the difference between diffusion and dissolving?

  554. What famous physicist was asked to become president of Israel?

  555. Why is Mercury the only metal present in the liquid state at room temperature?

  556. How far down can an object go in the ocean before it will reach 10,000 PSI?

  557. As scientists approach absolute zero, the speed at which an electrical current travels increases tremendously, correct? If so, would it be possible to say that our computers would work a little faster if they were in a freezer?

  558. Who is responsible for the theory/maxim/idea ... 'every action has an equal but opposite action'?

  559. A pendulum is hanging in a lift and is oscillating. The lift is given a free fall. What will happen to the bob of the pendulum?

  560. Why do you hear a glugging sound when you pour a liquid out of a bottle by holding it upside down?

  561. Why doesn't friction depend on surface area?

  562. Where can I get a list of friction coefficients for different materials?

  563. What is the string theory? Who came up with it / discovered it?

  564. Does the term wind chill only apply to humans, animals, etc. or does it also apply to material things like automobiles, tractors, etc.?

  565. Will a black container of hot water lose heat faster or slower than a white container of hot water?

  566. Why is simple harmonic motion 'simple'? Is there a complex harmonic motion?

  567. What is a quark?

  568. Please can you (briefly) tell me how the concept of 'non locality', or what Einstein referred to as 'spooky action at a distance' was arrived at?

  569. Why does increased pressure lower the melting point of ice? Can we use the First Law of Thermodynamics to explain?

  570. What is the Triple Point of Water?

  571. Since hydrofluoric acid (HF) will eat through just about anything, in what and how is it stored?

  572. Why is there no degree in Kelvin?

  573. If you were in a plane and shot a bullet vertically down from a gun and dropped a bullet by hand, at the same time, would they reach the earth at the same time?

  574. How does one determine the temperature of a vacuum?

  575. Does a car makes more pressure to the floor when it goes faster, or the car could fly if it goes even faster?

  576. I was told by my Physics instructor that there is such a thing as negative time. Is that true, or was he just pulling my leg?

  577. If an atomic clock is propelled at near the speed of light, wouldn't the definition of a second be distorted?

  578. If Newton's law of motion, which states that any object in motion will remain in motion, is true, then why is it that as a comet gets close to the sun and it melts, and a tail forms, and why wouldn't it be just a big ball of melted stuff?

  579. If you were to design a laser, how would you determine the wavelength of light that would be produced?

  580. Does Einstein's mass-energy equation (E = mc2) imply that the mass of an object increases when we give it enough energy, be it kinetic or otherwise?

  581. Where does lightening come from, clouds, ground or both?

  582. Two cars traveling at 60 mph collide head on. Another car crashes into a wall at 60 mph. Which one has more damage?

  583. If the term 'absolute motion' has no meaning, then why do we say that the earth moves around the sun and not vice versa?

  584. Since there are such things as anti-electrons and anti-protons, is there such a thing as an anti-neutron?

  585. Regarding natural units, how can h=c=1, and why is this simplification used?

  586. How come a drop of water can stay hanging from the ceiling without falling immediately on the floor? How does it stick to the ceiling surface?

  587. Is it possible to find the radius of an electron?

  588. Are the electrons spinning around the nucleus of an atom travelling faster than the speed of sound?

  589. What is film boiling?

  590. Do we weigh more at Death Valley than on top of Mount Everest and if we do would it be from gravity or from atmospheric pressure?

  591. Why does a piece of chalk produce a squeal if you hold it incorrectly. What determines the pitch you hear?

  592. What are the number of neutrons in each of elements?

  593. I am renting a storage space and found out the the space next to mine is storing 10 millicuries of cesium and 50 millicuries of americium. Is there any risks associated with articles that are stored near these elements?

  594. What is the formula to find the absorption coefficients of materials?

  595. Is the velocity of a baseball pitcher's arm 100 MPH if his pitch is clocked going that fast?

  596. Why does oil float to the top in liquid if you try to mix it with the liquid?

  597. What is the difference between fire and electricity? What is the role of electricity in combustion? Why is electricity prone to cause fires?

  598. Is it possible that a big enough particle accelerator ,(the RHIC for example), could generate a black hole. If so - how?

  599. When an electron tunnels from one place to another, does in happen instantaneously, or does it require a finite amount of time? Can things other than electrons tunnel?

  600. Can lightening travel through matter (specifically a canvas awning supported by aluminum poles) and strike the children sitting beneath on wooden tables supported by a concrete slab? If so, how do you calculate a safe distance from the lightening that is visible?

  601. Can an object be said to: accelerate from 50 km/h to 0 km/h? Or must one say that the object has decelerated?

  602. How is the photon energy related to photon frequency?

  603. How does matter couple to space-time so that space-time becomes curved?

  604. Is it true that in the late 1800's they took away or added 11 days to the calendar that didn't exist?

  605. Why is it, that if you lower your hand flat into, say, a pool there is no or hardly any resistance but if you were to raise your hand and slap it down hard into the water, there is so much resistance?

  606. How they can reach zero gravity in a plane (when astronauts are practicing)?

  607. Since the sun is one giant ball of gas, what force holds its consistent shape and size? Why doesn't it expand and burn up quickly?

  608. Why is the latent heat of vaporization of water greater than the latent heat of fusion of water?

  609. Is the angle at which the object rebounds, in a perfectly elastic collision, from the surface equal to that at which it is incident?

  610. Why is the speed of light considered to be the universal speed limit, and would it be possible to ever exceed that speed with some advanced technology?

  611. When you throw an object into the air, is the initial velocity the same as the velocity just before it hits the ground? If so, why?

  612. What happens to a closed can of coke when put in the freezer?

  613. Why does a solar eclipse move from west to east, while the sun moves from east to west?

  614. Why is it that when one is taking a hot shower, the shower curtain tends to be pulled inward, inside the shower(as opposed to being pushed outward)?

  615. What is your opinion on Smarandache's hypothesis that there is no speed barrier in the universe?

  616. I read somewhere that Einstein's formula is mostly quoted in the abbreviated version E=mc2 but it should actually be written E2=m2c4. Is that true?

  617. What is terminal velocity?

  618. How can I more easily visualize what a horse-power means?

  619. Is it possible for a patch of light to travel faster than the speed of light?

  620. Why does sound wave travel faster in a denser medium whereas light travels slower?

  621. Why is a light colored T-shirt cooler to wear than a dark colored T-shirt?

  622. Where is the force of gravity stronger, on the top of Mt. Everest or at sea level?

  623. Why do birds fly in formation shaped like the alphabet'V'? Which bird works the hardest in such a formation and why?

  624. Is weight determined strictly by the distance between and mass of two objects, or are other factors figured in; i.e. can a person be considered weightless underwater?

  625. Does a black hole violate the Law of Conservation of Matter/Energy?

  626. Does the earth's mass increase?

  627. Why can we see the sunlight for over 20 minutes even after sunset?

  628. If you have a very long and rigid pole and have an observer on each end, if one of them pushes the pole how soon will the other one feel it?

  629. How tall does a mirror have to be to fit an entire persons body?

  630. How is the distance to the stars measured?

  631. Which makes more sense: that photons [and other quantum objects] are neither waves nor particles or that they both waves and particles?

  632. How fast do electrons travel when moving as an electrical current through copper wire?

  633. Why is it that birds are able to stand/sit on electrical power lines whereas if we were to try this, we would be electrocuted?

  634. How fast must a car be travelling to generate 1G (gravity) of force on itself and it's occupants when stopped, as if hitting a wall?

  635. What is the definition of horsepower?

  636. How is the exact value of pi determined?

  637. Why does the Fahrenheit scale use 32 degrees as a freezing point?

  638. Why X-rays and Gamma-rays are different in nature, though both are of electromagnetic origin?

  639. When liquid boils what TYPE of gases are in the bubbles?

  640. How is water a good conductor of electricity?

  641. Would this be perpetual motion:
    1) You make hydrogen from water using energy.
    2) you let the H2 rise through a pipe capturing all its energy.
    3) you burn the H2 in a fuel cell at its highest height.
    4) Then you let the water from the fuel cell run down a pipe capturing all of its energy.
    5) Now all the energy you captured from the H2 rising, the fuel cell burning,and the water falling is used to make more H2.

  642. Everybody knows e=mc2 But what are the units?

  643. What speed defines Mach 1? and why?

  644. If I fire a cannon straight up into the air, the cannon ball slows down as it rises to its apex, then speeds up as it falls. At any given distance from the ground, is the ball travelling at the same speed on the way DOWN as it was on the way UP?

  645. When was the first experiment done, or how old is experimental physics?

  646. What is a geo-stationary orbit? Are there any other orbits?

  647. If I were in an elevator that was free falling, would it help at all if I perfectly timed a jump before it hit the ground floor? Would anything help the situation?

  648. What is a sonic boom and how is it produced?

  649. If there was a hole through the earth would you be stopped in the middle due to gravity or would you fall straight through?

  650. What is the temperature at which Fahrenheit and Celsius thermometer readings are equal?

  651. Why can you ride a bike with no hands?

  652. How many atoms thick is aluminum foil?

  653. How long does it take the sun's light to reach earth?

  654. I was told that UV rays can not go through glass but can go through quartz. Is that true?

  655. Who discovered the proton? And how was it discovered?

  656. What exactly is an ELECTRON VOLT as opposed to a VOLT?

  657. I got a speeding ticket and the cop told me he used a laser gun on me or the car in front of me. How does it work? I would like to fight the ticket.

  658. When you look at a spoon why is your reflection upside down?

  659. I know why the sky is blue during the day, and why it turns yellowish to reddish at sunrise and sunset. My question is; why doesn't the sky ever look green? Why does the color go from blue to yellow?

  660. How a satellite can pick up more speed after circling the sun? I believe it is called the slingshot effect? Wouldn't any speed gained from the gravitational pull of the sun be counteracted by the same gravity when the satellite was distancing itself from the sun?

  661. Expansion and Contraction : Why does heat and cold make things expand and contract ? Also why do some metals expand more than others?

  662. Why do dimples on a golf ball allow it to travel farther?

  663. Someone kindly explain,please.My atoms left the spot of the 'BIG BANG' at it's occurrence some 15 billion years ago.They traveled at a relatively slow rate compared to the speed of light.therefore,would not the light generated at BIG BANG time have passed me by and been long forgotten.Yet,we get reports of light from near the time of the BIG BANG just being received as if we had been here all along awaiting it?

  664. Why your ears pop when you are riding on an airplane?

  665. What is the physics behind the voice change which occurs when one inhales Helium?

  666. Is it possible to create an object that is composed of antimatter only?

  667. What is the fine-structure constant?

  668. How do you determine the distance of lightening from where you are standing using the sight of lightening and the sound of the thunder?

  669. Is the geographic NORTH pole of the earth a magnetic NORTH pole? Once you have reached the north pole of the earth, what happens to your compass? Which way would it be pointing?

  670. What are Newton's three laws?

  671. I was wondering why radioactive elements have a mutation effect on living things, how does this happen to both fully grown adults and unborn children?

  672. What will hold a greater amount of charge, a hollow metal sphere or a solid metal sphere?

  673. Is it true that radio waves travel faster than X-rays?

  674. Why does a Fire truck siren change pitch when it passes us?

  675. How do airplanes fly and where can I find more information about it on the internet?

  676. What is the Photoelectric Effect?

  677. If, indeed, the speed of light is constant,why is it usually listed for a vacuum?

  678. How was the speed of light determined and who found it, when? How close was the estimate of 186,000 mps to the 'actual' speed of light?

  679. Why does a high frequency pass through a capacitor and a low frequency doesn't?

  680. Why does sound travel faster in solids than in liquids, and faster in liquids than in gases (air)?

  681. In movies why do wheels of a moving car appear to rotate backwards to the actual direction?

  682. How do yo-yos work? Why do they come back up after being thrown down?

  683. Given that space is expanding, why is it that it is still '3,000 miles' from New York to San Francisco? Why is it that the volume of the space in a crystal lattice of, say, NaCl, still X cubic Angstroms? Doesn't 'local' space expand too?

  684. What is the physics behind a frisbee in flight?

  685. Can you compress a liquid (water)?

  686. How big is an atom of gold?

  687. Would not the speed of a light beam headed toward a black hole increase tremendously? We do know it could be bent by the gravity of a star.

  688. What determines the color of large bodies of water (i.e. Ocean/large lakes?)

  689. I know that gravity keeps us on the earth, but what prevents us from being pushed or pulled through the floor, earth, etc. (besides concrete, wood, and soil)? Does it have something to do with opposite forces?

  690. How are all magnetic fields produced? Where are the moving charges in the iron atoms of a magnet?

  691. Where do electrons get the energy to travel at such high speeds?

  692. Why can a person lay on a bed of nails and not be injured? What is this scientific theory called?

  693. Which freezes faster, hot water or cold water?

  694. Do falling objects drop at the same rate (for instance a pen and a bowling ball dropped from the same height) or do they drop at different rates?

  695. Could you tell me a technical name for sugar?

  696. What would light be like if there was no ability for light to make a rainbow?

  697. When you said E=mc2 ,what does the c stand for?

  698. What are the wavelengths of the basic colors (Red, Orange, Yellow, Green, Blue, Violet) in the color spectrum?

  699. Do you know where to find information on the temperature at the tip of a lit cigarette, both during drawing on it and when it is not being drawn on?