Question

A rod of weight W is supported by two parallel knife edges A and B and is in equilibrium in a horizontal position. The knives ate at a distance d from each other. The centre of mass of the rod is at distance x from A. The normal reaction on A is

(a) W(d-x)/x

(b) W(d-x)/d

(c) Wx/d

(d) Wd/x

Answer 1

Correct option (b) W(d-x)/d

Explanation:

 Given situation is shown in figure.

N₁ = Normal reaction on A

N₂ = Normal reaction on B

W = Weight of the rod

In vertical equilibrium,

N₁ + N₂ =W  ....(i)

Torque balance about centre of mass of the rod,