Question

The change in volume caused on stretching a rubber chord along its length is negligible. The Poission’s ratio for the material of the chord is

(1) 1

(2) 1/2

(3) 1/4

(4) 2

Answer 1

(2) 1/2

Let ‘r’ be the radius of the rubber chord of length 'l' . Suppose the chord is stretched to increase its length by Δl resulting in a decrease Δr in its radius. We have Longitudinal strain = Δl/l, Lateral strain = Δr/r

As volume of the chord remains constant, we have