Question
A spring when stretched by $2 \,mm$ its potential energy becomes $4 \,J$. If it is stretched by $10 \,mm$, its potential energy is equal to
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Answer
(d)$U = \frac{1}{2}k{x^2}$ if $x $ becomes $ 5$ times then energy will become $25 $ times i.e. $4 \times 25 = 100\,J$
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