Question

Identical springs of steel and copper$(Y_{steel} > Y_{copper})$ are equally stretched.

• A. Less work is done on copper spring.
• B. Less work is done on steel spring.
• C. Equal work is done on both the springs.
• D. Data is incomplete.

Answer 1

Answer: (B)

Less work is done on steel spring.

Answer 2

: Work done, $W = \frac{1}{2} \times F \times \Delta L$

For a given F

$W \propto \Delta L$

And $\Delta L = \frac{FL}{AY}$

As F, A and L are constants

$\therefore\Delta L \propto \frac{1}{Y}$

Form (i) and (ii), we get

$W \propto \frac{1}{Y}$

$\therefore\frac{{W_{steel}}_{}}{{W_{Copper}}_{}} = \frac{{Y_{copper}}_{}}{{Y_{steel}}_{}}$

$AsY_{copper} < Y_{steel}$

$\therefore W_{steet} < W_{copper}$

So, less work is done on steel spring.