Question

A bullet whose mass is 30.2 g leaves a rifle with a muzzle velocity of 1,000 m/s. It strikes a block of wood (mass 5 kg), initially at rest, and remains embedded in it. After the bullet hits the block, what will be the velocity of the bullet-block system?
a. 30.2
b. 1.51
c. 33.1
d. 165
e. 6
f. 7.6
g. 6,000

Answer 1

This problem here is an example of inelastic collision where kinetic energy is not conserved but momentum is. We calculate as follows:

m1v1 + m2v2 = (m1 + m2)v3
v3 = m1v1 + m2v2  / m1 + m2
v3 = (30.2)(1000) + (5000)(0) / (30.2 + 5000)
v3 = 6.00 m/s