Please help with a question about friction

[Prem1998]

Homework Statement

Three blocks A, B, and C of masses m1, m2 and m3 respectively are lying on top of each other on a frictionless table with A on top and C on bottom. The coefficient of friction between A and B is u1 and between B and C in u2. Find the accelerations a1, a2 and a3 of the three blocks if a horizontal force F is applied on:
(a) A, (b) B and (c) C
The force F is applied on one block at a time and the accelerations are noted and then it is applied on the second one then the third one giving us three sets of accelerations.

Homework Equations

The Attempt at a Solution

I can't get anything in my head.

 

[BvU]

First thing to do is make a drawing. You will notice it's impossible to draw three blocks on top of each other but you can draw a block C on top of B which is on top of A.
Then for each case make a free body diagram of each of the blocks. See if you have enough information to solve, or if you still need some additional assumptions (about sliding or not sliding )

Oh, and: you can't get started without some relevant equations. That's why there is a section 2 in the template. Check your notes or your textbook.

The equations link the variables that appear in your diagrams, so make a list of them (item 1 in the template ).

By the way, your thread may be deleted by a mentor for not showing any effort. See the guidelines