题目内容
质量为150kg的摩托车,由静止开始沿倾角为10°的斜坡以1m/s2的加速度向上行驶,若所受空气和摩擦总阻力是车重的0.03倍,摩托车的额定功率为4.5kW。
求:(1)它能维持匀加速行驶的时间是多少?
(2)行驶12.5m时摩托车的功率为多少?(sin10°=0.17)
求:(1)它能维持匀加速行驶的时间是多少?
(2)行驶12.5m时摩托车的功率为多少?(sin10°=0.17)
(1)10s(2)![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824193918287795.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824193918287795.png)
试题分析:(1)根据牛顿第二定律:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824193918552833.png)
解得加速阶段的牵引力:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824193918864610.png)
加速阶段的末速度
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824193919238969.png)
它能维持匀加速行驶的时间:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824193919535666.png)
由
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824193919894553.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824193920346948.png)
则此时摩托车仍在匀加速阶段其功率为
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824193918287795.png)
点评:本题难度较小,力决定运动,因此要先分析受力,求得加速度后转化为运动学问题再求解
![](http://thumb2018.1010pic.com/images/loading.gif)
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