The formal procedure for taking equipment out of service and ensuring it cannot be operated until an unauthorized person has returned it to service is

See explanation below for answer.

Explanation:

Newton's third law of motion states that, for every action, there is an equal and opposite reaction.

In the scenario presented above, we can see that for every time the child pushes against the ground, the ground also pushes against the child with opposing but equal force, that corresponds to the force that the child has pushed against it with.

This action and reaction is what enables the child to be able to jump the rope.

Therefore, the action is the child pushing against the ground, the reaction is manifested in the jump, as the ground pushes against the child with equal force.