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
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.