What is static friction?

What is static friction?

• A. Friction that enables motion
• B. Friction that causes sliding
• C. Resisting friction
• D. Force that pulls toward the center

Answer: (C)

Static friction is the frictional force that resists the initiation of motion between two surfaces that are in contact and at rest relative to each other. It acts opposite to the direction of the impending motion and can vary in magnitude up to a maximum value, μ_s N, where N is the normal force. This means you can push on an object with a range of forces without it moving, because static friction adjusts to balance your push until you reach that maximum. Once the push exceeds μ_s N, the object begins to slide and kinetic friction takes over, which is usually smaller in magnitude. The other descriptions don’t fit because friction does not enable motion, it opposes it; static friction specifically resists the start of sliding, and the idea of a centripetal force refers to something different—the force that acts toward the center of a circle.

Static friction is the frictional force that resists the initiation of motion between two surfaces that are in contact and at rest relative to each other. It acts opposite to the direction of the impending motion and can vary in magnitude up to a maximum value, μ_s N, where N is the normal force. This means you can push on an object with a range of forces without it moving, because static friction adjusts to balance your push until you reach that maximum. Once the push exceeds μ_s N, the object begins to slide and kinetic friction takes over, which is usually smaller in magnitude. The other descriptions don’t fit because friction does not enable motion, it opposes it; static friction specifically resists the start of sliding, and the idea of a centripetal force refers to something different—the force that acts toward the center of a circle.