4．有两个物体a和b,其质量分别为ma和mb,且ma>mb．它们的初动能相同．若a和b分别受到不变的阻力Fa和Fb的作用,经过相同的时间停下来,它们的位移分别为Sa和Sb,则

                                                                                                                              （    ）

A．Fa>Fb且sa<sb                                                                         B．Fa>Fb且sa>sb

C．Fa<Fb且sa>sb                                                                         D．Fa<Fb且sa<sb

  • 答案
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