题目内容
⑴列车在行驶过程中所受的阻力大小.
⑵列车的额定功率.
⑶列车从开始运动到停下所经过的总路程
(1)6×104 N(2)
(3)14 km
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120247915486.gif)
⑴依题意可求刹车时列车的加速度
················· 2分
由牛二律,得
················································· 2分
代入数据可求得
=6×104 N················································ 2分
⑵列车的额定功率
··········· 4分
⑶对列车运动全过程由动能定理有
····················· 4分
代入数据可求得s1=1.4×104 m=14 km································· 2分
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120247930635.gif)
由牛二律,得
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120247946473.gif)
代入数据可求得
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120247962216.gif)
⑵列车的额定功率
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120247977935.gif)
⑶对列车运动全过程由动能定理有
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120247993546.gif)
代入数据可求得s1=1.4×104 m=14 km································· 2分
![](http://thumb2018.1010pic.com/images/loading.gif)
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