Question

A copper wire of length 3m and 1mm diameter is subjected to a tension of 5N. Calculate the elongation produced, if the young’s modulus of copper is 120GPa.

(a) 15m

(b) 1800m

(c) 0.125 ×10^-3 m

(d) 15.9mm

This question was addressed to me during an online exam.

This intriguing question originated from Elasticity topic in section Thermal Properties of Matter of Engineering Physics I

Answer 1

Correct option is (d) 15.9mm

Explanation: Young’s modulus = (Force ×Length)/(Area ×Elongation); Area=πr^2

Elongation = (Force ×Length)/(Area ×Young’s modulus)

Elongation = 15.9mm.