Two wooden crates rest on top of one another. The smaller top crate has a mass of m1 = 21 kg and the larger bottom crate has a mass of m2 = 91 kg. There is NO friction between the crate and the floor, but the coefficient of static friction between the two crates is μs = 0.82 and the coefficient of kinetic friction between the two crates is μk = 0.65. A massless rope is attached to the lower crate to pull it horizontally to the right .What is the maximum tension that the lower crate can be pulled at before the upper crate begins to slide?

Question

anonymous · Answer

The mass of the upper crate and the coefficient of static friction allows you to calculate the maximum force that friction can provide to accelerate the upper crate.
That determines the maximum acceleration without slipping of the upper crate.
The acceleration then lets you determine the corresponding tension in the rope.