If the coefficient of friction is 0.20 and the normal force is 10 N, what is the frictional force?

If the coefficient of friction is 0.20 and the normal force is 10 N, what is the frictional force?

• A. 0.5 N
• B. 1 N
• C. 2 N
• D. 5 N

Answer: (C)

Frictional force depends on how hard the surfaces press together and how rough they are. Its magnitude is f = μN. Here the normal force is 10 N and the coefficient of friction is 0.20, so f = 0.20 × 10 = 2 N. This force acts to oppose motion along the contact surface. The other numbers would imply different μ values (e.g., 0.5 N would need μ = 0.05, etc.), which don’t match the given coefficient.

Frictional force depends on how hard the surfaces press together and how rough they are. Its magnitude is f = μN. Here the normal force is 10 N and the coefficient of friction is 0.20, so f = 0.20 × 10 = 2 N. This force acts to oppose motion along the contact surface. The other numbers would imply different μ values (e.g., 0.5 N would need μ = 0.05, etc.), which don’t match the given coefficient.