如图所示在皮带传动中，右轮半径比左轮半径大．已知它们在转动过程中不打滑，则下列说法正确的是（ ）
A．右轮转动的角速度大于左轮转动的角速度
B．左轮转动的角速度大于右轮转动的角速度
C．两轮边缘上的所有的点线速度大小相等
D．右轮边缘上的点线速度大小大于左轮边缘上的点的线速度大小
两个轮子靠传送带传到，且不打滑，轮子边缘上的点在相等时间内走过的弧长相等，则两轮边缘上所有点的线速度大小相等．根据v=rω知，半径越大，角速度越小，则右边转动的角速度小于左边转动的角速度．故B、C正确，A、D错误．
故选BC．
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| One night recently, I was driving down a highway at about 60 miles an hour. A car came from the 1 direction at about the same speed. As we 2 each other, I looked into the driver's eyes for a second. I 3 whether he might be thinking, as I was, how 4 we were on each other at that moment. I was relying on him not to fall 5 , not to cross over into my lane (车道) and bring my 6 to a sudden end. He relied on me in just the same way without 7 . I believe that is the way the world 8 . At some level, we all depend upon 9 . Sometimes that dependence requires us simply not to 10 over the double yellow line. Sometimes it requires us to 11 cooperatively (同心协力地), with friends or even 12 . 13 technology makes our world smaller, the need increases for cooperation. In 2003, doctors in five nations were encouraged to 14 the causes of SARS, saving thousands of lives. The 15 of international terrorism has shown itself to be a similar 16 , one requiring the 17 across the world. We must 18 that our future is not controlled by ourselves alone. I've come to believe that one must rely upon the good faith and judgment of others. So, while 19 alone down a dark road, we must know the coming light may not be a danger, but a 20 moment of trust. | ||||
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