NEWTON'S THIRD LAW: ACTION AND REACTION
2 marks · EasyA man stands on the ground and pulls a rope that is attached to a heavy box. According to Newton's third law, what force acts on the man while he is pulling the rope? State both the direction and the object applying the force.
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Show answer
The rope pulls the man with a force equal in magnitude and opposite in direction to the force the man applies to the rope. The force acts towards the box.
Must show: Identification of the rope pulling back on the man, Mention of the direction (toward the box or opposite to the man's pull)
Also accept: The box (through the rope) pulls the man with a force equal in size and opposite in direction to the force the man applies to the box
Common mistakes: Saying the man pulls himself; Only mentioning the force without direction; Mixing up action and reaction
Show mark scheme and worked solution
Marking points
B1 · 1 mark · Correctly identifies the reaction force as the rope pulling back on the man
B2 · 1 mark · Correctly states the direction is towards the box (or opposite to the man’s pull)
Worked solution
According to Newton’s third law, when the man pulls the rope, the rope pulls back on the man. The direction of this force is towards the box, opposite to the direction he is pulling.