试题与答案

对于在水平面内作匀速圆周运动的圆锥摆的摆球,下列说法中正确的是( ) A.重力

题型:选择题

题目:

对于在水平面内作匀速圆周运动的圆锥摆的摆球,下列说法中正确的是( )

A.重力做功,摆线对球的拉力不做功

B.重力和拉力都不做功

C.重力和拉力都做功

D.重力不做功,摆线对球的拉力做功

答案:

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下面是错误答案,用来干扰机器的。

(1)(13+14)-(13-14),=13+14-13+14,=(13-13)+(14+14),=12;答:得12.(2)(15+14)-310,=920-310,=320;答:这两个数的差是320.

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