Question

a particle starting sliding down from the top of a smooth inclined plane of inclination 30° and length 40 m find time & velocity​

Answer 1

Assumption: Initial velocity of the body is zero.

The body will slide down with a constant acceleration as the force acting on the body is constant.

Using second equation of motion,

s=ut+1/2at²

Let the total distance along the plane be L.  

Then, for one-fourth of the distance,

L/4=1/2a×2²       (I)

For complete distance,

L= 1/2a×t²          (ii)

Using (I) & (ii), t=4 s