# Homework Help: Equilibrium equation for a frame

1. Nov 27, 2013

### princejan7

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

http://postimg.org/image/scm11r483/

So when considering the free body diagram for member BE, why is the force P not included?

Does the Ex account for the bit of the P=210 that would act on member BE?

2. Nov 27, 2013

### Staff: Mentor

The problem statement seems to imply that the force is acting on the pin. The pin is then assumed to exert a force Ex on member BE. In the problem solution, moments are taken about the pin, so the force at E doesn't matter in this moment balance. However, the solution implicitly assumes that the moment at the pin is zero (i.e., BE rotates freely at the pin).

3. Nov 27, 2013

### PhanthomJay

Did you solve for Ex? It's quite a bit of P.
In the FBD of the member, the internal cut is made an infinitesimal distance away from the joint, so it does not include P in your FBD of the member, just internal forces Ex, Ey, CD, and the external roller vertical reaction.