試題詳解

3. A uniform disk with mass m and radius R is rolling down on a 30° inclined plane without slipping. What is the frictional force between the disk and plane? (g: free-fall acceleration)
(A) 0
(B) 1/6 mg
(C) 1/3 mg
(D) 1/2 mg
(E) 2/3 mg