Friction/Movement of Blocks down inclined plane

[ehunger1]

Homework Statement

The given diagram is an inclined plane with a 15 degree angle. There are three boxes, A, B, and C all weighing 4 kg. The three packages are touching, but B is in the middle and larger than A and C, which are the same size.
The coefficients of friction for A and C are static=.30 and kinetic=.20
The coefficients of friction for B are static=.10 and kinetic=.08

Determine which, if any, of the packages will move and the friction force acting on each box.

Homework Equations

SUM Fx=0
SUM Fy=0

The Attempt at a Solution

I've determined the weight of each box is 39.2 N (F=ma)
For box A (closest to the angle of the inclined plane)
tan(15)=.268 < .3=static coefficient, therefore, block A will not move on its own
SUM Fx=f1-39.2sin(15)=0
SUM Fy=N1-39.2cos(15)=0
f1=friction force=10.15 N
N1=Normal Force from plane=37.9N

I don't know how to treat the blocks being in contact with each other. I know there should be a normal force there, and I know that for block B, tan(.15)=.268>.1, therefore on its own, block B would move. Block C will not move because it is identical to block A and there is no force acting on it to push it down the ramp.

How do I know if block A and B move?

 

[ehunger1]

Help? Someone?

 

[kerimek]

I would suggest conducting an experiment to determine if blocks A and B move. This could involve setting up the inclined plane and blocks in a controlled environment and measuring the movement of the blocks over a set period of time. You could also vary the weight of the blocks or the angle of the incline to see how it affects the movement.

In terms of the friction forces acting on each block, you have correctly calculated the friction force for block A. For block B, you would use the same equations but with a different angle (since it is not at the steepest point of the incline). The normal force for block B would also be different, as it is not in contact with the incline. As for the blocks being in contact with each other, you could consider the normal force between them as being the same as the normal force between the block and the incline. However, this may not accurately reflect the real-world scenario, so it would be important to consider the limitations of this assumption in your experiment.