What Horizontal Force Tips a Crate with Given Friction and Mass?

[ama]

Homework Statement

A uniform crate with a mass of 14.1 kg rests on a floor with a coefficient of static friction equal to 0.551. The crate is a uniform cube with sides 1.21 m in length.
If a horizontal force is applied to the top of the crate, what is the magnitude of the horizontal force needed to cause it to start tipping?
uS=.551
mass=14.1

Homework Equations

t=0

The Attempt at a Solution

I have no idea how to solve this problem,but i know it has something to do with torques. What do i set the axis of rotation to so i can get the torque caused by friction and normal.

 

[omoplata]

Yes, it has something to do with the torque.

Assume the crate is about to tip around one of the four lower edges. Take the torque around that edge. The torque due to the horizontal force has to be balancing the torque due to weight of the crate.