On a level surface, which force balances gravity?

On a level surface, which force balances gravity?

• A. Friction
• B. Air resistance
• C. Normal force
• D. Gravitational force

Answer: (C)

The key idea is force balance in the vertical direction. Gravity pulls the object downward with weight mg, and the surface pushes upward with a normal force. On a level surface, these two vertical forces can cancel each other, so the net vertical force is zero and there is no vertical acceleration. The normal force is the contact force perpendicular to the surface that provides this upward push, which is why it balances gravity. Friction acts along the surface and would only affect horizontal motion, while air resistance is typically along the direction opposite motion through the air and doesn’t balance the weight in this setup.

The key idea is force balance in the vertical direction. Gravity pulls the object downward with weight mg, and the surface pushes upward with a normal force. On a level surface, these two vertical forces can cancel each other, so the net vertical force is zero and there is no vertical acceleration. The normal force is the contact force perpendicular to the surface that provides this upward push, which is why it balances gravity. Friction acts along the surface and would only affect horizontal motion, while air resistance is typically along the direction opposite motion through the air and doesn’t balance the weight in this setup.