Which friction occurs when surfaces are sliding against each other?

Which friction occurs when surfaces are sliding against each other?

• A. friction force
• B. kinetic friction
• C. static friction
• D. pending motion

Answer: (B)

When surfaces move past each other, the friction present is kinetic friction. It is the resistive force that acts opposite the direction of the relative motion as sliding occurs, and its magnitude is typically modeled as F_k = μ_k N, where μ_k is the coefficient of kinetic friction and N is the normal force. This is distinct from static friction, which only resists impending motion and has a maximum value μ_s N; once motion begins, friction switches to the kinetic type. The other terms aren’t standard descriptions of friction during sliding, and “pending motion” isn’t a real category. So the friction occurring during sliding is kinetic (sliding) friction.

When surfaces move past each other, the friction present is kinetic friction. It is the resistive force that acts opposite the direction of the relative motion as sliding occurs, and its magnitude is typically modeled as F_k = μ_k N, where μ_k is the coefficient of kinetic friction and N is the normal force. This is distinct from static friction, which only resists impending motion and has a maximum value μ_s N; once motion begins, friction switches to the kinetic type. The other terms aren’t standard descriptions of friction during sliding, and “pending motion” isn’t a real category. So the friction occurring during sliding is kinetic (sliding) friction.