In an effort to move the two crates, each of weight W, which are stacked on top of one another, the man pushes horizontally on them at the bottom of crate A as shown. Determine the smallest force P that must be applied in order to cause impending motion. Explain what happens. The coefficient of static friction between the crates is μs and between the bottom crate and the floor is μs'.

Given:

W = 100 lb

μs = 0.8

μs = 0.3

a = 2 ft

b = 3 ft