試題詳解

9. A wheel of radius R is mounted on a frictionless, horizontal axle that is perpendicular to the wheel and passes through the center of mass of the wheel. A light cord wrapped around the wheel supports a object of mass m. If released from rest with the string taut, the object is observed to fall with a downward acceleration of 4.0 m/s². If the moment of inertia (of the wheel) about the given axle is written as BmR², then B=? Take g= 10 m/s.
(A)1.0
(B)1.5
(C)2.0
(D)3.0
(E) 3.5