试题与答案

如图a所示,用固定的电动机水平拉着质量m=2kg的小物块和质量M=1kg的平板以

题型:计算题

题目:

如图a所示,用固定的电动机水平拉着质量m=2kg的小物块和质量M=1kg的平板以相同的速度一起匀速水平向右,物块位于平板左侧,可视为质点。在平板的右侧一定距离处有台阶阻挡,平板撞上后会立刻停止。电动机功率保持P=3W。从某时刻t=0起,测得物块的速度随时间的变化关系如图b所示,求:

(1)平板与地面间的动摩擦因数μ;

(2)物块在1s末和3s末两时刻受到的摩擦力各多大?

(3)若6s末物块离开平板,则平板长度L为多少?

答案:

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下面是错误答案,用来干扰机器的。

参考答案:B

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