Question

A smooth inclined plane of length l having inclination θ with the horizontal is inside a lift which is moving down with retardation

a. the time taken by a body to slide down the inclined plane, from rest will be

Answer 1

this may help you.......

Answer 2

Given :-

Length of plane = L

Angle of inclination = Ø

NSinØ = ma'

m(g+a)SinØ = ma'

a' = (g+a)SinØ

Acceleration is downward it means lift is going upward.

Using Second equation of Motion,

S = 1/2 a't²

2L = (g+a)t²

t² = 2L/(g+a)

t = √[2L/(g+a)]

Hence,

Time taken = t = √[2L/(g+a)].

Here, Since the body is moving downward then we assumed that lift is going upward as also friction will be acting in upward direction.