A person pushes against a wall with 50 N. What force does the wall exert on the person?

A person pushes against a wall with 50 N. What force does the wall exert on the person?

• A. 50 N exerted on the wall.
• B. 0 N; the wall does not push back.
• C. 50 N in the opposite direction to the push.
• D. The wall exerts a force proportional to friction.

Answer: (C)

Newton's third law shows that forces come in action–reaction pairs with equal magnitudes and opposite directions. When you push the wall with 50 N, the wall pushes back on you with 50 N in the opposite direction. This reactive force is the normal contact force the wall exerts on your hand. The magnitude must match your push because they are two forces of the same interaction acting on two different objects. So the wall exerts 50 N on you, directed opposite to your push. The other ideas fail because they either talk about the force you apply on the wall (not the force on you), or ignore the interaction, or bring in friction—which isn’t the needed factor here since the reaction is the normal force perpendicular to the surface.

Newton's third law shows that forces come in action–reaction pairs with equal magnitudes and opposite directions. When you push the wall with 50 N, the wall pushes back on you with 50 N in the opposite direction. This reactive force is the normal contact force the wall exerts on your hand. The magnitude must match your push because they are two forces of the same interaction acting on two different objects. So the wall exerts 50 N on you, directed opposite to your push. The other ideas fail because they either talk about the force you apply on the wall (not the force on you), or ignore the interaction, or bring in friction—which isn’t the needed factor here since the reaction is the normal force perpendicular to the surface.