If a wire 30cm long is extended to 30.5cm by a force of 300N. Find the strain energy of wire?

A. 0.75 J
B. 7.50 J
C. 75.00 J
D. 750.00 J

Correct Answer:

Option A – 0.75 J

Explanation

Energy stored in a stretched wire (strain energy)
= average force x extension
= ½Fe
= ½ x 300N (30.5 – 30.0) x 10^-2 m
= 150 x 0.5 x 10^-2  = 0.75J