Answer
The answer to (b) does not depend on the mass of the sphere.
Work Step by Step
In part (a), we found that the expression for the total kinetic energy of a sphere moving at a speed $v$ is $K = \frac{7}{10}Mv^2$
The gravitational potential energy at the highest point on the incline will be equal to the kinetic energy at the bottom of the incline.
We can find an expression for the distance $d$ that the sphere travels along the incline:
$U = K$
$Mgh = \frac{7}{10}Mv^2$
$g~d~sin~\theta= \frac{7}{10}v^2$
$d = \frac{7~v^2}{10~g~sin~\theta}$
Note that the expression for the distance $d$ does not depend on the mass of the sphere.
