《功和机械能》单元测试题一(参考答案)

1、功和机械能单元测试题一（参考答案）DIV.MyFav_1326680514018P.MsoNormalTEXT-JUSTIFY:inter-ideograph;FONT-SIZE:10.5pt;FONT-FAMILY:"TimesNewRoman"TEXT-ALIGN:justifyDIV.MyFav_1326680514018LI.MsoNormalTEXT-JUSTIFY:inter-ideograph;FONT-SIZE:10.5pt;FONT-FAMILY:"TimesNewRoman"TEXT-ALIGN:justifyDIV.MyFav_13

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7、ABCD二、填空题11050W12864J80%13动能和势能是可以相互转化的；由于空气摩擦，使得机械能减小14大卡车小15机械能三、实验题16 （1）控制变量法（2）0.7560.984%（3）结论一：在斜面的粗糙程度相同时，斜面的倾角越大，机械效率越高。结论二：在斜面的倾角相同时，斜面的粗糙程度越大，机械效率越低。17 （1）ac纸盒子被推动距离（2）让小球从斜面的同一高度由静止滚下（3）ab四、计算题18解：1.6t=1600Kg108Km/h=30m/S20min=1200s（1） F=f=0.1G=0.1mg=0.1X1600KgX10N/Kg=1600N（2） W=FS=1600N30m/SX1200s=5.76X107J（3） P=W/S=5.76X107J/1200s=4.8X104J19解：绕法如图，绳子段数n=4。（ 1）因为，所