A roller of mass (m) is placed on an inclined plane making an angle (θ) with the horizontal. Normal force is acting upward to the inclined surface. Garvitational force mg acts on roller in the downward direction. The weights on the pan are hung with thread while the other end is attached to the mass through the pulley fixed at the top of the inclined plane.
The normal force acting on the roller is given by,
N=mg cos⁡θ

If the angle of inclined is greater than the angle of repose, such that the velocity v with which the roller slide down the incline, then

We assume that there is no friction. So, µ_r mg cos⁡θ becomes zero. Hence,
F=mg sin⁡θ

If the total tension W₁<W, the roller moves down and W₂>W, roller moves upward.

Then the downward force acting on the roller along the inclined plane will be W=(W₁+W₂)/2 which must be equal to the mg sin⁡θ.
For constant mass, m

W∝sin⁡θ