Speed of Bullet, up and Down
Most recent answer: 05/06/2018
- Leonardo (age 45)
Seaside,ca
There are indeed two forces on the bullet after it leaves the gun, but "energy" is not one of the forces. The two forces causing the velocity to change are gravity and air friction.If gravity were the only force then it would speed up the falling bullet just the same amount that it slowed down the rising bullet. That would leave the speed near the ground the same on the way down as on the way up. One way of thinking of that is that the gravity leaves the kinetic energy of motion plus the potential energy which depend on height) unchanged. When the height is the same, the kinetic energy would be the same so the speed would be the same, whether it's going up or down. The air friction, however, always acts to slow the bullet down. It pulls energy from the bullet's motion and transfers it to heat in the bullet and the nearby air. It causes the falling bullet to have less energy and move slower than the rising bullet near the ground.
Mike W.
(published on 05/06/2018)