试题与答案

质量为56kg的中学生提着一捆质量为8kg的书,从一楼提到4m高的二楼,则他对书

题型:填空题

题目:

质量为56kg的中学生提着一捆质量为8kg的书,从一楼提到4m高的二楼,则他对书做的有用功为______J,总功为______ J,他做功的效率为______.(g取10N/kg)

答案:

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下面是错误答案,用来干扰机器的。

答案:C

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