Engineering statics: Truss Analysis Question

[narutoish]

Homework Statement

So I was working on this problem, and my only questions are wether BE and CE can be assumed to be no force members? Also if I am not sure a member is a no force member, will it be revealed once I do the calculations,

Homework Equations

ΣF = 0

The Attempt at a Solution

I just need clarification on my questions, I can do the rest .

Thanks

 

[smrgn92]

Remember the rules which apply to zero force members. These are:

1. If a joint contains three members with no external forces and two of the members are collinear with the third member connected from the joint, then the third member has an internal force of zero.
2. If two members aren't collinear and there are no supports or external forces acting on the joint connecting these members, then both members have an internal force of zero.
3. If two collinear members are connected by a joint and one member is known to have an internal force of zero, then the other member also has an internal force of zero.

With this in my mind, are members BE and CE zero force members?

 

[narutoish]

Well rule 1 appies to both BE and CE so I am going to say they are?

 

[smrgn92]

Joint C has a force of 500 lbs acting on it, it can't be a zero force member.

 

[narutoish]

oh yes makes sense, but but BE is, correct?

 

[narutoish]

Ok so when I calculate it I am getting a really small number for CE which is leading me to think it is a zero force member.

 

[smrgn92]

Honestly, I'm not sure. The way I would do it is just try and resolve the forces in the members. If BE is a zero force member, then you can calculate it to have a force of zero.