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?
Asked by: David A. Fechtor
Answer
The speed of the cannon ball is the same on its way both to and from the apex at every point between the ground and the apex, because the force of gravity decelerates it (as it approaches the apex) at the same rate as it accelerates it (as it departs from the apex).
Answered by: Howie Soucek, BS Philosophy, Hampden-Sydney College, VA
Additional comment by Anton Skorucak, PhysLink.com Editor:
The above stated answer is not entirely correct in the case where one has to deal with drag or friction of the air. Namely,
'In a way science is a key to the gates of heaven, and the same key opens the gates of hell, and we do not have any instructions as to which is which gate.
Shall we throw away the key and never have a way to enter the gates of heaven? Or shall we struggle with the problem of which is the best way to use the key?'