10-year-old Sarah on a skateboard pushed by her brother Jack

What is the relationship between the force of Jack on Sarah and the force of Sarah on Jack?

A. Greater than the force of Sarah on Jack.

B. Equal to the force of Sarah on Jack.

C. Less than the force of Sarah on Jack.

Answer:

The correct answer is A. Greater than the force of Sarah on Jack.

When Jack pushes Sarah on the skateboard, the force he exerts on her is equal and opposite to the force Sarah exerts on Jack. This is known as Newton's Third Law of Motion. However, the acceleration of Sarah and the skateboard depends on the net force acting on the system.

If the force of Jack on Sarah is greater than the force of friction between the skateboard and the ground, then the net force is in the backward direction and Sarah speeds up. Therefore, the force of Jack on Sarah is greater than the force of Sarah on Jack in this scenario.

This does not imply that Jack is physically stronger than Sarah. It simply means that he is exerting a greater force on her in this particular situation due to the direction of the forces involved.