Question

A body sliding on asmooth inclined plane requires $4$sec to reach the bottom after starting from rest at the top.How much time does it take to cover one fourth the distance starting from the top.

Answer 1

$U=0m/s$

$t=4sec$

$a=9m/s^2$(acceleration due to gravity)

$s=ut+\frac{1}{2}a{t}^2$

$s=0\ast 4+\frac{1}{2}\ast 9\ast 4\ast 4$

$s=72m$

$\frac{1}{4}of72=18m$

Now,$s=18m,u=0m/s,a=9m/s^2$

$s=ut+\frac{1}{2}a{t}^2$

$18=0\ast t+\frac{1}{2}\ast 9\ast t^2=\frac{1}{2}\ast 9t^2$

$t^2=2\ast 2$

hence,$t=2$