1. The 85-lb force P is applied to the 200-lb crate, which is stationary before the force is applied. Determine the magnitude and direction of the friction force F exerted by the horizontal surface on the crate.
2. The coefficients of static and kinetic friction between the 100-kg block and the inclined plane are 0.30 and 0.20, respectively. Determine
(a) the friction force F acting on the block when P is applied with a magnitude of 200 N to the block at rest,
(b) the force P required to initiate motion up the in- cline from rest, and (c) the friction force F acting on the block if P = 600 N.
