Let angle of the inclined plane with the horizontal be =

Now if an object of mass 'm' is kept on the plane.
Then component of gravitational force along the plane = mg sin

, down the plane
Now if the system is accelerated by 'a' then pseudo force on the object = ma, in the horizontal direction.
Also the component of this force along the plane = ma cos

(along the plane but opposite to the component of gravitational force.
Thus for equilibrium of particle to occur
mg sin

=ma cos

or a = g tan
