Question

A 13 g bullet traveling 213 m/s penetrates a 2.0 kg block of wood and emerges cleanly at 152m/s. If the block is stationary on a frictionless surface when hit, how fast does it move after the bullet emerges?

Answer 1

Due to the conservation of linear momentum:

p (before) = p (after)

m1u1 + m2u2 = m1v1 + m2v2

0.013*213 + 2*0 = 0.013*152 + 2.0*v

2.769 = 1.976 + 2v

2v = 0.793

v = 0.397ms-1