A horizontal force presses the block of mass 10kg to the wall. What is the minimum magnitude of the applied force which can hold the block on the wall without accelerating it down if the coefficient of static friction (pico per second) between the block and the wall is 0.40.

Answer 1

force of gravity down = m g = 98 N

friction force up = mu F = .4 F
so
.4 F = 98

F = 98/.4