题目内容

如图所示,长12m,质量100kg的小车静止在光滑水平地面上。一质量为50kg的人从小车左端,以4m/s2加速度向右匀加速跑至小车的右端(人的初速度为零)。求:

(1)小车的加速度大小;

(2)人从开始起跑至到达小车右端所经历的时间;

(3)人从开始起跑至到达小车右端对小车所做的功。

解:(1)对人有,                                                                

对板有,                                                                     

板与人水平方向相互作用,故大小相等

解得板 a2=2m/s2                                                                       

(2),                                                                                 

,                                                                             

,                                                                              

解得t=2s                                                                                       

(3)木板末速度                                                               

                                         


解析:

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