Question 4
Two children sit on two boards resting on glass balls. If only one of them pushes the other palm to palm, what happens?
The right answer is the one marked above.
Both children move, in opposite directions. Even when only one pushes, both move.
The child pushing applies a force to the other — that is the action. The other child then applies a force of the same magnitude in the opposite direction back on the pusher — that is the reaction.
No willingness "to push" is required. The second child can do nothing at all and the reaction force still arises — the law has no exceptions.