A 20-g bullet is fired into a 2.0-kg block of wood placed on a horizontal surface.The bullet stops in the block.The impact moves the block (+ bullet)a distance of 5 m before it comes to rest.If the coefficient of kinetic friction between the block and surface is 0.25,calculate the speed of the block (+ bullet)system immediately after impact.
A)20 m/s
B)3.5 m/s
C)25 m/s
D)5.0 m/s
E)2.2 m/s

Question

Quizplus · Accepted Answer

The work done by friction (friction force times distance) equals the initial kinetic energy of the block and bullet system. Using the formula for kinetic energy and the friction force, we can solve for the initial speed.

A 20-G Bullet Is Fired into a 2