Question

Two wooden crates rest on top of one another. The smaller top crate has a mass of m1 = 18.0 kg and the larger bottom crate has a mass of m2 = 94.0 kg. There is NO friction between the crate and the floor, but the coefficient of static friction between the two crates is μs = 0.8 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 (which should be considered the positive direction for this problem).


The tension is increased in the rope to 1213.0 N causing the boxes to accelerate faster and the top box to begin sliding. What is the acceleration of the upper crate?

As the upper crate slides, what is the acceleration of the lower crate?

Answer 1

First you need to find how much force the top crate is pushing on the bottom crate due to gravity. That will allow us to get a sense of the effect of the friction.

Answer 2

i know the force the bottom has on the top 63.64

Answer 3

Okay so you can multiply that by each coefficient of friction to find out how much the force they are going to apply on the bottom box in the opposite direction.

Answer 4

then what do i do?

Answer 5

Figure out whether it slips or not. Figure out the net force on the top block.

Answer 6

im sorry but im confused