题目内容
(10分)如图所示,一辆质量为 2.0×103 kg 的汽车在平直公路上行驶,若汽车行驶过程中所受阻力恒为f = 2.5×103N ,且保持功率为 80 kw 求:
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250000120562060.jpg)
( l )汽车在运动过程中所能达到的最大速度;
( 2 )汽车的速度为 5m/s 时的加速度 ;
( 3 )汽车的加速度为0.75m/s2时的速度。
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250000120562060.jpg)
( l )汽车在运动过程中所能达到的最大速度;
( 2 )汽车的速度为 5m/s 时的加速度 ;
( 3 )汽车的加速度为0.75m/s2时的速度。
(1) 32m/s;(2)
6.75
;(3)
m/s
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000012072299.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000012088488.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000012103493.png)
试题分析:(1) 因汽车匀速直线运动时速度最大,
由
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000012119573.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000012134407.png)
得:
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000012166367.png)
(2) 设
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000012181298.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000012197333.png)
则
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000012228526.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000012244623.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000012072299.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000012088488.png)
(3)设
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000012290762.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000012306353.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000012322657.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000012337538.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000012103493.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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