Find the acceleration of the blocks

[jyothsnapb]

Homework Statement

Find the acceleration of the blocks if a horizontal force of 10 N is applied on the 7 kg block.
u1, u2 and u3 are the coefficients of friction. refer diagram. thanks in advance

Homework Equations

The Attempt at a Solution

the force of friction between 7 kg and 3 kg is 15 N which is more than the applied force so they will move together like a single block. I am confused abt the motion of the 4 kg block will it move with a different acceleration or same?

 

[tiny-tim]

hi jyothsnapb!

do questions like this systematically …

call the accelerations of the three blocks a₁ a₂ and a₃,

then write out F = ma equations for each block …

what do you get? ​