Question

A spring of length 1m has two cars connected to both of its ends. The two cars move towards eachother such that the spring is compressed to 0.5m. If the spring constant is 500 N/m, what is the elastic potential energy stored?

(a) 125 J

(b) -125 J

(c) 62.5 J

(d) -62.5 J

The question was asked by my school teacher while I was bunking the class.

The question is from The Potential Energy of a Spring in division Work, Energy and Power of Physics – Class 11

Answer 1

Correct choice is (c) 62.5 J

The best explanation: PE = 1/2*k*d^2

 = 1/2 x 500 x (-0.5) ^2

 = 62.5 J.

The elastic potential energy is positive even for negative displacement.