Basketball - Hang Time

Pro basketball players seem to float in the air while they're at the basket with the ball. Of course, this is just an illusion; they fall at the same rate as they rose into the air, assuming they don't make contact with anything. What makes the time seem longer is probably because after their bodies reach their highest point, they extend their arms upward, giving the illusion that they're still going up. They are also moving forward when they jump, which also affects our perception of time. Here's an example. Imagine firing a bullet from a rifle, directly at a monkey hanging from the branch of a tree a kilometre away. If the monkey lets go of the branch just as you fire, will you hit him? Leaving aside the environmentally sensitive issue of whether or not we should be shooting monkeys out of trees, this is actually a well-known physics problem. In fact, the moment the bullet leaves your gun in a horizontal line, it will begin to fall. It will fall with exactly the same acceleration downwards as the monkey. Regardless of how far away the monkey is, when the bullet reaches the tree, it will have fallen the same distance as the monkey. It will hit him!This seems unlikely, since we usually visualize bullets as travelling in a straight line. But as any hunter will tell you, they do fall. If aimed horizontally, the bullet will hit the ground in the same time another bullet would, if you dropped it from the same height as your gun.The 'hang time' of a pro basketball player at the net seems longer because he is moving forwards and upwards. It is harder to consciously be aware of how long it took him to go up, when he is also moving forwards. But if you used a stopwatch and a slow-motion replay, you would discover that the time from when he left the floor to when he stops moving upward is exactly equal to the time he takes to fall, and there is no hang time! The instant he stops going up, he starts to fall. But this is hard to see when things happen fast and there is forward movement.