A body moving at 2m/s can be stopped over a distance x. If its kinetic energy is doubled, how long will it go before coming to rest, if the retarding force remains unchanged

Q : A body moving at 2m/s can be stopped over a distance x. If its kinetic energy is doubled, how long will it go before coming to rest, if the retarding force remains unchanged

(A) x

(B) 2x

(C) 4x

(D) 8x

Solution : If R = Retarding force

Rx1 = ΔK.E1 = K … (i)

Rx2 = ΔKE2 = 2K . . .(ii)

Dividing (ii) by (i)

x2 = 2x1

= 2x

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