Question

The potential energy of a certain spring when stretched through a distance 'S' is 10 joules. The amount of work (in joule) that must be done on this spring to stretch it through an additional distance 'S' will be

• A. 30
• B. 40
• C. 10
• D. 20

Answer 1

The correct option is A 30

We know that Potential energy is $u=\frac{1}{2}K{s}^2$

So, on substituting we have $\Rightarrow$ $10=\frac{1}{2}K{s}^2$

Workdone, $W=\frac{1}{2}K({2s)}^2-\frac{1}{2}K{s}^2$

$W=2K{s}^2-\frac{1}{2}K{s}^2$

$=\frac{3}{2}K{s}^2$

Thus, $W=3\times 10=30$ Joules