Q: A body sliding down on a smooth inclined plane slides down 1/4 th distance in 2 sec. It will slide down the complete plane in
(a) 4 sec
(b) 2 sec
(c) 5 sec
(d) 3 sec
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Ans: (a)
Sol: As u = 0, and a is constant
Applying $\displaystyle S = u t + \frac{1}{2}a t^2 $
In first case ,
$\displaystyle S/4 = 0 + \frac{1}{2}a 2^2 $ ..(i)
In second case ,
$ \displaystyle S = 0 + \frac{1}{2}a t^2 $ ..(ii)
Dividing (ii) by (i), we get
$ \displaystyle 4 = \frac{t^2}{4}$
t = 4 sec