A 20-g bullet moving at 1000 m/s is fired through a one-kg block of wood emerging at a speed of 200 m/s.What is the change in the kinetic energy of the bullet-block system as a result of the collision assuming the block is free to move?
A) 0 J
B) −9.5 kJ
C) 9.5 kJ
D) −18 J

Question

Quizplus · Accepted Answer

The initial kinetic energy of the bullet is 10,000 J, and the final kinetic energy is 400 J. The block's final kinetic energy is 800 J. The change in kinetic energy is (400 + 800) - 10,000 = -9,500 J, or -9.5 kJ.

A 20-G Bullet Moving at 1000 M/s Is Fired Through