A 20.0 g rubber bullet traveling with a velocity of 60.0 m/s hits a stationary 3.00 kg wood block resting on a frictionless surface. The rubber bullet
ricochets off the wood block with a velocity of 40.0 m/s in the opposite
direction.
A. Find the velocity of the wood block.

0.667 m/s

Explanation:

Given that,

Mass of a rubber bullet, m₁ = 20 g = 0.02 kg

Initial speed of rubber bullet, u₁ = 60 m/s

Mass of the wood block, m₂ = 3 kg

Initial speed of the wooden block, u₂ = 0

A rubber bullet hits the stationary wood block. The rubber bullet  ricochets off the wood block with a velocity of 40.0 m/s in the opposite  direction.

Final speed of rubber bullet, v₁ = -40 m/s

Using the conservation of momentum. It will remains conserved. Let v₂ is the velocity of the wood block.

So, the velocity of the wood block is 0.667 m/s.