A hollow cylinder with a very thin wall (like a toilet paper tube) and a block are placed at rest at the top of a plane with inclination \theta above the horizontal. The cylinder rolls down the plane without slipping and the block slides down the plane; it is found that both objects reach the bottom of the plane simultaneously. What is the coefficient of kinetic friction between the block and the plane?
Answer Choices
A. 0
B. \frac{1}{3} \tan \theta
C. \frac{1}{2} \tan \theta
D. \frac{2}{3} \tan \theta
E. \tan \theta