沿平直公路匀速行驶的汽车上,固定着一个正四棱台,其上下台面水平,如图为俯视示意图。在顶面上四边的中点a、b、c、d 沿着各斜面方向,同时相对于正四棱台无初速释放4 个相同小球。设它们到达各自棱台底边分别用时Ta、Tb、Tc、Td,到达各自棱台底边时相对于地面的机械能分别为Ea、Eb、Ec、Ed(取水平地面为零势能面,忽略斜面对小球的摩擦力)。则有
A.Ta =" Tb" =" Td" = Tc,Ea > Eb =" Ed" > Ec |
B.Ta =" Tb" =" Td" = Tc,Ea =" Eb" =" Ed" = Ec |
C.Ta < Tb =" Td" < Tc,Ea > Eb =" Ed" > Ec |
D.Ta < Tb =" Td" < Tc,Ea =" Eb" =" Ed" = Ec |
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