Which type of friction acts when two surfaces slide past one another?

Which type of friction acts when two surfaces slide past one another?

• A. Kinetic
• B. Static
• C. Rolling
• D. Viscous

Answer: (A)

When two surfaces slide past one another, the friction that resists that motion is kinetic friction. This type of friction comes into play only once sliding occurs. Static friction, on the other hand, resists the start of motion and acts up to a maximum value before sliding begins. Rolling friction occurs when an object rolls rather than slides, and viscous friction is the resistance you feel in fluids, proportional to velocity. In sliding situations, the frictional force is roughly constant and depends on the normal force and the coefficient of kinetic friction, often with μs ≥ μk. A common example is pushing a book across a table: you must overcome static friction to start, and once it slides, kinetic friction opposes the motion.

When two surfaces slide past one another, the friction that resists that motion is kinetic friction. This type of friction comes into play only once sliding occurs. Static friction, on the other hand, resists the start of motion and acts up to a maximum value before sliding begins. Rolling friction occurs when an object rolls rather than slides, and viscous friction is the resistance you feel in fluids, proportional to velocity. In sliding situations, the frictional force is roughly constant and depends on the normal force and the coefficient of kinetic friction, often with μs ≥ μk. A common example is pushing a book across a table: you must overcome static friction to start, and once it slides, kinetic friction opposes the motion.