Question

The Young’s modulus of three materials are in the ratio 2 : 2 : 1. Three wires made of these materials have their cross-sectional areas in the ratio 1 : 2 : 3. For a given stretching force the elongation's in the three wires are in the ratio

(a)  1 : 2 : 3

(b)  3 : 2 : 1

(c)  5 : 4 : 3

(d)  6 : 3 : 4

Answer 1

Correct option  (d) 6 : 3 : 4

Explanation:

l = FL/AY and for a given stretching force l ∝ 1/AY

Let three wires have young's modulus 2Y, 2Y and Y and their cross sectional areas are A, 2A and 3A respectively.