Question

The density of a certain rod a foot long varies directly as the square of the distance from one end. Find the centre of gravity.

(a) 4/3a

(b) 3/4a

(c) 1/3a

(d) 1/4a

This question was addressed to me in class test.

I want to ask this question from Centres of Gravity and Moments of Inertia of Area topic in division Development of Surfaces, Isometric Projections, Perspective Projections & Transformation of Projections of Civil Engineering Drawing

Answer 1

Right choice is (b) 3/4a

Best explanation: Place the rod on the x-axis, one end at the origin so that ρ = kx^2,

where a is the length of the rod.