A person pushes on a wall with a force of 200 N. What force does the wall exert on the person?

A person pushes on a wall with a force of 200 N. What force does the wall exert on the person?

• A. 100 N
• B. 400 N
• C. 0 N
• D. 200 N

Answer: (D)

When two objects push on each other, the forces they exert are equal in magnitude and opposite in direction. So if a person pushes a wall with 200 N, the wall pushes back on the person with 200 N in the opposite direction. That reaction force has the same strength as the push and opposite direction, which is why the force from the wall on the person is 200 N. The other numbers don’t fit this equal-and-opposite interaction: there is a contact force of 200 N, not 0, 100, or 400 N.

When two objects push on each other, the forces they exert are equal in magnitude and opposite in direction. So if a person pushes a wall with 200 N, the wall pushes back on the person with 200 N in the opposite direction. That reaction force has the same strength as the push and opposite direction, which is why the force from the wall on the person is 200 N. The other numbers don’t fit this equal-and-opposite interaction: there is a contact force of 200 N, not 0, 100, or 400 N.