Question

The potential energy of a spring when stretched through a distance x is 10 J. What is the amount of work done on the same spring to stretch it through an additional distance x?

• A. 10 J
• B. 20 J
• C. 30 J
• D. 40 J

Answer 1

Answer: (C)

30 J

Answer 2

Potential energy of the spring when stretched through a distance x,

$\mathrm { U } = \frac { 1 } { 2 } \mathrm { kx } ^ { 2 } = 10 \mathrm {~J}$

When x becomes 2x, the potential energy will be

work done