A 1 kg block is held at rest against a rough vertical wall by a horizontal force F. The coefficient of friction is 0.5. Which statements are correct?

Question

G1 Physics · Accepted Answer

The block weight is 10 N, so actual friction required for equilibrium is 10 N upward. It is possible whenever μF ≥ 10, i.e. F ≥20 N. Thus at 30 N and 20 N the friction is 10 N, and the minimum force is 20 N. At 40 N friction is still 10 N, not 20 N.