3.(xz100000000009)一绕中心轴转动的圆盘,角速度为w,若将它放在摩擦系数-|||-为μ水平桌面上,问经过多长时间停下来?(已知圆盘质量为m半径为R,绕轴-|||-的转动惯量为 =dfrac (1)(2)m(R)^2 ) ()-|||-(A) dfrac (3R)(4mu g) (B) dfrac (5R)(4mu g)-|||-(C) dfrac (3omega )(4R/g) (D) dfrac (3Romega )(4mu g)