Question

Angie, brad, and carlos are discussing a physics problem in which two identical bullets are fired with equal speeds at equal-mass wood and steel blocks resting on a frictionless table. One bullet bounces off the steel block while the second becomes embedded in the wood block. All the masses and speeds are the same, says angie, so i think the blocks will have equal speeds after the collisions. But what about momentum? asks brad. The bullet hitting the wood block transfers all its momentum and energy to the block, so the wood block should end up going faster than the steel block. I think the bounce is an important factor, replies carlos. The steel block will be faster because the bullet bounces off it and goes back the other direction.

Answer 1

Answer:

Momentum must be conserved in the collision.

The steel block must move faster after the collision to preserve momentum.

If the steel block is moving faster it will aso have more kinetic energy.

(Note; If the bullet hits the steel block it will have some momentum in the reverse direction and thus have a greater change in total momtntum than the bullet that becomes imbedded in the wood block)