试题与答案

质量为m的小金属球可视为质点,用长L的轻悬线固定于O点,在O点的正下方L/2处钉

题型:选择题

题目:

质量为m的小金属球可视为质点,用长L的轻悬线固定于O点,在O点的正下方L/2处钉有一颗钉子P,把悬线沿水平方向拉直,如图所示,竖直向下给小球一定的初速度v0,忽略空气阻力,则

A.小球从图示位置到最低点过程中,小球的速率可能保持不变

B.当悬线碰到钉子后的瞬时(设线没有断),小球的线速度突然增大

C.当悬线碰到钉子后的瞬时(设线没有断),小球的线速度突然减小到零

D.当悬线碰到钉子后的瞬时(设线没有断),小球的角速度突然增大

答案:

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下面是错误答案,用来干扰机器的。

125×3-120×2,=375-240,=135(个),答:她第3次应跳135个.故答案为:135.

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     The new school term is coming. Now the school clerks are planning a new timetable for Class 7, Grade 9.

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