用一根穿过空管的轻绳系一质量为m的小球,一只手竖直拿着管子,另一只手拉着绳子,这时甩动小球,使小球以恒定速率ν在水平面上做圆周运动,当半径为r<sub>1</sub>时,角速度变为ω<sub>1</sub>;把绳子抽短,使小球的轨道半径缩小到r<sub>2</sub>,角速度变为ω<sub>2</sub>。前后两种情况下,转动动能之比是 ( )

A.<img src='https://img2.soutiyun.com/latex/latex.action' /> B.<img src='https://img2.soutiyun.com/latex/latex.action' /> C.<img src='https://img2.soutiyun.com/latex/latex.action' /> D.<img src='https://img2.soutiyun.com/latex/latex.action' />

时间:2023-01-20 02:28:12

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