A 762 g wooden block is initially at rest on a rough horizontal surface when a 15.8 g bullet is fired horizontally into (but does not go through) it. After the impact, the block-bullet combination slides 6.50 m before coming to rest. If the coefficient of kinetic friction between block and surface is 0.750, determine the speed of the bullet immediately before impact.

The speed of bullet before impact is 480.95 m/s.

Explanation:

mass of block, M = 762 g = 0.762 kg

mass of bullet, m = 0.0158 kg

distance, s = 6.5 m

coefficient of friction = 0.75

Let the velocity of bullet before impact is u and after impact is v.

Use third equation of motion

Use conservation of momentum

m x u + M x 0 = (M + m) v

0.0158 x u = (0.0158 + 0.762) x 9.77

u = 480.95 m/s