Test: Shear Force & Bending Moment - 2 - Civil Engineering (CE) MCQ

BMD will be of 2^nd degree, so the correct answer is (d).

∴  2x² = y²

Taking moment about A = 0

R₂ = 2W
But, ∑F_v = 0
⇒ W + 2W + W - R₁ - R₂ = 0 
⇒ R₁ = 4W - 2W = 2W

Since the given beam is loaded symmetrically, therefore the reactions at each suportwill be equal i.e. W

In section BD, shear force is zero. Hence this section subjected to pure bending.

In a bending beam, the point of contraflexure in a beam is the location where the bending moment is zero and changes its sign. The point of contraflexure (PoC) occurs where bending is zero and at the point of change between positive and negative (or between compression and tension). 

M = V · x
dM/dx = V
i.e. Rate of change of bending moment is shear force.

Taking moments about A. We get 
M - R₂ + L = 0
⇒ R₂ = M/L
Since these is no vertical loading hence the reactions are equal and oposite.
Bending moment is given by