Statics: Equilibrium of Machines

[physicsss]

The problem is stated in the picture. And I drew the FBDs of the top half of the bolt cutter, as shown in the second page:

Setting moment about A to be 0, I obtain -Q(1 in)-FBy*4 in=0
And By= -Q/4 lb

Then setting moment about C to be zero. I obtain
FBy(0.5 in)-20 in(75 lb)=0
Substitute in By, I get the magnitude of Q to be 12000 lb.

UPDATE: PICS
Problem:
http://img368.imageshack.us/img368/7535/1239zw.jpg
FBD's:
http://img368.imageshack.us/img368/431/22cm.jpg Am I correct?

 

[Pyrrhus]

What was the problem then?, it looks good to me (the procedure, i didn't do the arithmetic).

 

[physicsss]

The problem just seems...too easy...

 

[Pyrrhus]

I was checking the problem again you forgot the Bx component when you did moment about C, it does have a moment, and the lever arm for 75 about c is 19.5

 

[okoo]

AE is 2-force member (so the reaction at A is only Ay), so that Bx is actually zero (due to the equilibrium eqs of AB). Then you can solve the rest of them.