Question

Consider a 8.0-kg red block pressed against a wall falling at -2.5 m/s. Given the following coefficients between the wall and the block--μk = 0.4 and μs = 0.7, determine the force of the hand that acts on the block. Use g = 9.79 m/s

Answer 1

mg = f
mg= umF

Answer 2

Since there is no acceleration, the friction force balances the gravity force.
and since the block is in motion, $$f=mg=\mu F$$
(Not umF).

Answer 3

oh sorry..thanks