题目内容
提高物体(例如汽车)运动速率的有效途径是增大发动机的功率和减小阻力因数(设阻力与物体运动速率的平方成正比,即Ff=kv2,k是阻力因数).当发动机的额定功率为P0时,物体运动的最大速率为vm,如果要使物体运动的速率增大到2vm,则下列办法可行的是
A.阻力因数不变,使发动机额定功率增大到2P0 |
B.发动机额定功率不变,使阻力因数减小到![]() |
C.阻力因数不变,使发动机额定功率增大到8P0 |
D.发动机额定功率不变,使阻力因数减小到![]() |
CD
试题分析:当发动机的额定功率为P0时,物体运动的最大速率为vm,有P0=fvm=kvm3.则k=
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825005001131577.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825005001146391.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825005001084394.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825005001084394.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825005001193364.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825005001115432.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825005001115432.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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