Question

Young's modulus for a steel wire is 2 x 10¹¹ Pa and its elastic limit is 2.5 x 10⁸ Pa. By how much can a steel wire 3 m long and 2 mm in diameter be stretched before the elastic limit is exceeded?

(a) 3.75 mm

(b) 7.50 mm

(c) 4.75 mm

(d) 4.00 mm

Answer 1

Correct option (a) 3.75 mm

Explanation :

The cross-sectional area of a wire of radius r = 1 mm = 10^-3 m is

The maximum force that can be applied without exceeding the elastic limit is therefore

When this force is applied, the wire will stretch by