# Finding the magnitude of a couple

1. Oct 14, 2008

### Heat

1. The problem statement, all variables and given/known data

The 140-lb uniform steel plate ABCD is welded to shaft EF and is maintained in the position shown by the couple M. Knowing that collars prevent the shaft from sliding in the bearings and that the shaft lies in the yz plane, plot the magnitude M of the couple as a function of θ for 0<= θ<=90.

Diagram

2. The attempt at a solution

From what I understand, this problem requires a system equivalent to zero.
Sum of F = 0
Sum of M (along EF) = 0

I am having problems setting/getting started on this problem.

2. Oct 14, 2008

### minger

What is $$\theta$$? A diagram might be useful.

3. Oct 14, 2008

### Heat

I uploaded the pic, just click on the word 'diagram'. :)

4. Oct 14, 2008

### Pyrrhus

Heat, do you understand why they are giving you the weight of the plate? and yes you need to find the equation of sum of M along the axis EF and equal it to 0.

Start by setting the equation.