Question

A hollow cylinder of radius R rotates about its axis which is vertical. A block remains in contact with the inner wall if the frequency of rotation is f hertz. but falls at lower frequencies. The coefficient of friction between the block and cylinder is

Answer 1

REF.Image

F the frictional force= mg

for the block to stay

N= centripetal force = mwr

F= $\mu$ mwr

$\mu$ m $2\pi fr=mg$

$\mu =\frac{g}{2\pi fr}$