问题
填空题
质量为m的物体，沿半径为R的圆形轨道滑下，如图所示，当物体通过最低点B时速度为v0 ，已知物体和轨道间的动摩擦因数为μ，则物体滑过B点时受到的摩擦力大小为____
答案
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质量为m的物体，沿半径为R的圆形轨道滑下，如图所示，当物体通过最低点B时速度为v0 ，已知物体和轨道间的动摩擦因数为μ，则物体滑过B点时受到的摩擦力大小为____
| 从方框中选出与下列各句中画线部分意思相同或相近，并能替换画线部分的选项。 | |
( )2. Lin Fei goes to school at about 7 every day. ( )3. At that time Town Cinema was the cheapest ,but it had the friendliest service. ( )4. Sarah discovered that it was important for a flight attendant to speak English well. |