How to find the minium coefficient of static friction?

[ARJewell]

Homework Statement

For a system (with frictionless pulley) Mewsubk = .25 and the system is initially at rest. The mass of block 1 is 16 kg and the mass of block 2 is 12 kg. Determine the minimum coefficient of static friction needed to prevent any movement.

Homework Equations

F=ma

The Attempt at a Solution

I have no idea how to figure it out.
I figured out the acceleration to be 2.8m/s^2 because:
a= 12kg*9.8m/s^2 - .25*16kg*9.8m/s^2/(16kg+12kg)
I figured out the tension in the connecting string to be 84 N because:
T=mewsubk*m1g+m1a


Any help on how to figure out minimum coefficient of static friction?

 

[tiny-tim]

Welcome to PF!

Hi ARJewell ! Welcome to PF!

(have a mu: µ and try using the X₂ tag just above the Reply box )

… Determine the minimum coefficient of static friction needed to prevent any movement.
…
F=ma

No, if movement is prevented (or even, in a different question, where the block is just moving), a must be zero!

Try again. ​