Question

At a construction site, a pallet of bricks is to be suspended by attaching a rope to it and connecting the other end to a couple of heavy crates on the roof of a bulding. The rope pulls horizontally on the lower crate, and the coefficient of static friction between the lower crate and the roof is 0.666
a) what is the weight of the heaviest pallet of bricks that can be supported this way? Start with appropiate free-body diagrams
b) what is the friction force on the upper crate under the condition of part a?

Answer 1

Upper crate just adds to the weight of the lower one. Total 400 lb = 181 kg = 1778 N

friction force = 1778 N x 0.3333 = 593 N

that is 60.5 kg or 133 US lb