Which of the following is NOT one of the three types of friction described?

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

Answer: (B)

Friction is typically described in three main forms: static friction, kinetic (sliding) friction, and rolling friction. Static friction acts to prevent motion when two surfaces are at rest relative to each other, with a maximum value determined by the normal force and the coefficient of static friction. Once motion starts, kinetic friction comes into play, usually lower in magnitude than the maximum static friction, opposing the sliding motion. Rolling friction occurs when an object rolls instead of slides, and it is generally much smaller than sliding friction because contact is brief and involves less surface deformation. Magnetic interactions can influence motion, but they are not classified as one of the standard friction types; when magnets oppose motion, that’s a magnetic force or braking effect, not a basic friction category.