题目内容
右图是自行车传动机的示意图,其中Ⅰ是大齿轮,Ⅱ是小齿轮,Ⅲ是后轮。
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241333024665778.png)
⑴假设脚踏板的转速为
r/s,则大齿轮的角速度是___rad/s;
⑵要知道在这种情况下自行车前进的速度有多大,除需要测量大齿轮Ⅰ的半径
,小齿轮Ⅱ的半径
外,还需要测量的物理量是![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133302606191.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133302606191.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133302606191.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133302606191.png)
⑶用上述量推导出自行车前进速度的表达式:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241333024665778.png)
⑴假设脚踏板的转速为
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133302497304.png)
⑵要知道在这种情况下自行车前进的速度有多大,除需要测量大齿轮Ⅰ的半径
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133302544299.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133302559325.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133302606191.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133302606191.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133302606191.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133302606191.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133302606191.png)
⑶用上述量推导出自行车前进速度的表达式:
⑴
⑵后轮的半径
⑶![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133302918723.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133302793478.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133302825310.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133302918723.png)
(1)根据角速度定义,
;
(2)后轮的半径![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133302825310.png)
(3)根据同一轮子上角速度相等,同一传送链上线速度相等可得:
,
,
,联立得自行车前进速度的表达式:v3=
。
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133303090581.png)
(2)后轮的半径
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133302825310.png)
(3)根据同一轮子上角速度相等,同一传送链上线速度相等可得:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133303339656.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133303433735.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133303480790.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133302918723.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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