In the diagram below, a 60 kg roller skater pushes a 30 kg

roller skater with a force of 5 N. The force exerted by the 30 kg

roller skater on the 60 kg roller skater is __N.

Answer: 5 Newtons.

Explanation:

By the third Newton's law, every action has a reaction equal in magnitude and in the opposite direction, then the force exerted by the 30kg roller skater on the 60kg roller skater also is 5N.

This force will acelerate less the heavier skater because he has less mass, but the force is the same in both skaters.