# Roll Roll Roll the sphere gently on the plank!

Classical Mechanics Level 3

A solid sphere of mass $$2$$ kg and radius $$0.1$$ m is placed on plank with rough surface and of equal mass. But the plank lie on a smooth horizontal surface. The sphere is now given a sharp impulse in horizontal direction so that it starts sliding with a speed $$18 \frac{m}{s}$$. After some time the sphere starts pure rolling on the plank. Given that the coefficient of friction between plank and sphere is $$0.5$$. Now your task is just to find what is the time taken by sphere to start Pure rolling on the Plank in milliseconds. And take acceleration due to gravity, g = $$10 \frac{m}{s^2}$$.

×