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

Use conservation of momentum. Before the boy lands, the total forward momentum is (50 kg)(1.5 m/s) + (125 kg)(0 m/s) = 75 kg·m/s. After he jumps into the boat, they move together with a combined mass of 175 kg, so their velocity is 75 ÷ 175 ≈ 0.43 m/s forward. The correct choice is A, 0.43 m/s, forward.

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