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 = resistance
Rx1 =ΔKE1 = KE . .. (i)
Rx2 = ΔKE2 =2KE . . . (ii)
Dividing (ii) by (i)
x2 = 2x1 = 2x