1. What is the force in member CG?
a) 0
b) W
c) W/2
d) W/√2
Explanation: ∑V = 0 & ∑M = 0
W/2 = FCG SIN 45°
FCG = W/√2.
2. What is the force in member CD?
a) 0
b) W (Compressive)
c) W (Tensile)
d) W/2 (Compressive)
Explanation: ∑MG = 0
FCD X L + (W/2) X 2L = 0
FCD = W (Compressive).
3. What is the force in member FG?
a) 0
b) W/2 (Tension)
c) W/2 (Compression)
d) W (Compressive)
Explanation: ∑MC = 0
FFG X L + (W/2) X L = 0
FFG = W/2.
4. What is the force in member EH?
a) 0
b) W ( Compressive)
c) W ( Tension )
d) W/2 (Compressive)
Explanation: ∑MB = 0
FHE X L = 0
FHE = 0.
5. Find the Force in member DG.
a) W (Tensile)
b) W (Compressive)
c) 0
d) W/2 (Compressive)
Explanation: ∑V = 0
W + FDG = 0
FDG = W (Compressive).
6. Method of the section can always be used to calculate the force in any members.
a) True
b) False
Explanation: Method of the section has its own limitation. It cannot be used to compute the force of the member attached to a joint where already forces in more than one member is unknown.
7. What is the simplest element of a space truss?
a) triangle
b) tetrahedron
c) octahedron
d) pyramid
Explanation: Simplest element of a space truss is built on a basic triangle.
8. How many additional members are required to make a simple space truss from a basic tetrahedral element?
a) 1
b) 2
c) 3
d) 4
Explanation: Three additional members forming 1 extra joint are needed to form multi-connected tetrahedrons aka simple space truss.
9. How many equations are solved per joints while solving space trusses?
a) 1
b) 2
c) 3
d) 4
Explanation: 3 equations are solved per joint. Forces are conserved in all the three directions.
B= no. of bars of the truss
R= total no. of external support reaction
J= total no. of joints.
10. If B=6, R=6 and J= 4, then the truss is:-
a) statically determinate
b) statically indeterminate
c) stable
d) unstable
Explanation: B + R = 12 = 3*J. So, truss is statically determinate. Without further insight, we can’t predict stability.