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When a 4 kg mass is hung vertically on a...

When a 4 kg mass is hung vertically on a light string that obeys Hooke's law, the spring stretches by 2 cm. The work required to be done by an external agent in stretching this spring by 5 cm will be (`g=9.8(metrs)/(sec^2)`)

A

4.9 J

B

2.4 J

C

0.495 J

D

0.24 J

Text Solution

Verified by Experts

The correct Answer is:
B
(b) We have `k=(F)/(x)=(mg)/(x)`
`(4xx9.8)/(2xx10^(-2))=19.6xx10^(2)`
Work done `=(1)/(2)xx19.6xx10^(2)xx(0.05)^(2)=2.45` Joule
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