A 70-kg man is standing in a 20-kg boat.The man steps to the right thinking he is stepping out onto the dock.However,the following will actually happen (ignore the friction of the water or air on the boat or the man):
A)The man only moves a short distance to the right while the boat moves a larger distance to the left.
B)The man actually stays still while the boat moves toward the left.
C)The boat doesn't move and the man moves to the right.
D)None of the above.

Question

Quizplus · Accepted Answer

According to Newton's Third Law of Motion, for every action, there is an equal and opposite reaction. When the man steps to the right, he exerts a force on the boat towards the left. As a result, the boat will move in the opposite direction to the man. Since the mass of the boat is smaller than that of the man, the boat will move a larger distance in the opposite direction to the man's movement. Therefore, the man will only move a short distance to the right, while the boat will move a larger distance to the left.

A 70-Kg Man Is Standing in a 20-Kg Boat