Question

A 50 kg boy runs and jumps with a forward velocity of 1.5 m/s into a 125 kg stationary boat.

What is the final velocity of the boy/boat system?

0.43 m/s, forward
0.43 m/s, backward
1.1 m/s, forward
1.1 m/s, backward

Answer 1

Use conservation of momentum. Initial momentum = 50 kg × 1.5 m/s = 75 kg·m/s. Total mass after jumping = 50 + 125 = 175 kg.

v_final = 75 / 175 = 3/7 ≈ 0.4286 m/s, forward.

Answer: 0.43 m/s, forward.