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5.Work, Energy, Power and Collision
easy
The potential energy of a long spring when stretched by $2\,cm$ is $U$. If the spring is stretched by $8\,cm$, potential energy stored in it will be $.......\,U$
A
$16$
B
$2$
C
$4$
D
$8$
(NEET-2023) (AIPMT-2006)
Solution
$U =\frac{1}{2} k x^2$
$\text { for } x =2$
$U =\frac{1}{2} k (2)^2……..(1)$
$U ^{\prime}=\frac{1}{2} k (8)^2……….(2)$
$\text { Eq. (2)/eq. (1) }$
$\Rightarrow \frac{U^{\prime}}{U^{\prime}}=\left(\frac{8}{2}\right)^2$
$\Rightarrow U^{\prime}=16\,U$
Standard 11
Physics
