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A block of mass 5 kg is resting on a smo...

A block of mass 5 kg is resting on a smooth surface at what angle a force of 20 N be acted on the body so that it will acquire a kinetic energy of 40 J after moving 4 m?

A

`30^@`

B

`45^@`

C

`60^@`

D

`120^@`

Text Solution

Verified by Experts

The correct Answer is:
C
According to work energy theorem,
`W = DeltaKE`
`implies FS cos theta =1/2 mv^2 -1/2 "mu"^2`
`implies 20 xx 4 xx cos theta = 40 implies cos theta =1/2`
`implies cos theta = cos 60^@ implies theta = 60^@`
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