An object of mass m is released from rest from the top of a smooth inclined plane of height h. Its speed at the bottom of the plane is proportional to

Let v be the speed of the object at the bottom of the plane.
According to work--energy theorem,
$\mathrm{W} = ∆\mathrm{K} = {\mathrm{K}}_{\mathrm{f}}-{\mathrm{K}}_{\mathrm{i}}$

mgh = $\frac{1}{2}{\mathrm{mv}}^2-\frac{1}{2}{\mathrm{mu}}^2 (\therefore \mathrm{u} = 0)$

or $\mathrm{v}= \sqrt{2\mathrm{gh}}$

From the above expression, it is clear that v is independent of the mass of an object.