True or False a In a coplanar truss you can write down up to

True or False:

a) In a co-planar truss, you can write down up to three equilibrium equations per joint.

b) In analyzing a truss, when calculations based on equilibrium equations yield a negative value for a member force, the member is under tension if you initially assumed it to be under compression, and vise versa.

c) In the method of section applied to a co-planar truss, you can write down up to 3 equilibrium equations per part.

d) When you use the method of sections for a co-planar truss, you need to section it so that only up to 3 members are cut through.

e) Generally when analyzing a simple truss, the method of section is used when member forces are needed only in a few members.

Solution

(A) False - two equations per joint as Fx=0 and Fy=0

(B) True

(C) True - Fx=0, Fy=0, and Mo=0 for each part

(D) True - Method of Sections allows solving for up to three unknown forces at a time, you should choose sections that involve cutting through no more than three members at a time.

(E) True - Forces only at the cut section are obrained.