Question

According to Newton’s third law of motion, whenever one object exerts a force on a second object, the first object experiences a force that is equal in magnitude and opposite in direction to the force that it exerts. The forces are called action-reaction forces. The equal forces do not cancel out each other because the forces are acting on different objects.



An example of Newton’s third law of motion is movement of a boat forward when a person uses a paddle to push the water backwards.









Why does the force exerted by the water not cancel the force applied by the person on the water?


Because the forces act only on water.


Because the forces act only on the rowboat.


Because the forces act on both the water and on the rowboat.


Because the forces neither act on the water nor on the rowboat.

Answer 1

Because the forces act on both the water and on the rowboat.

The person/paddle pushes the water (force on the water) and the water pushes the paddle/boat (equal and opposite force on the boat); they don't cancel because they act on different objects.