A body sliding on a smooth inclined plane requires `4s` to reach the bottom, starting from rest at the at the top. How much time does it take to cover ont-foruth the distance startion from rest at the top?

Options

A. 1 s
B. 2 s
C. 3 s
D. 4 s

Answer

B

Explanation

Body at rest starts sliding down from
given `t = 4 s `
Here u = 0 `implies a = g sin theta `
Distance covered
` s = 0 xx 4 + (1)/(2) (g sin theta ) (4)^(2) " " … (i)`
In second case
Body rolls up from rest
Hence , u = 0 `implies a = - g sin theta `
Here , distance covered
`(s)/(4) = 0 xx t - (1)/(2) (g sin theta) (t^(2)) " " ... (ii)`
Dividing Eq.(i) and (ii) , we get
`(s)/((s)/(4)) = ((1)/(2) ( g sin theta ) (4)^(2))/(- (1)/(2) ( g sin theta ) (t)^(2)) implies t = 2 s `