小明用同一滑轮组分别将甲、乙两组钩码提升相同的高度,如图11所

小明用同一滑轮组分别将甲、乙两组钩码提升相同的高度,如图11所示。他两次提升钩码所用的拉力分别为FF,则F_______F;所做的有用功分别为WW,机械效率分别为ηη,则W________Wη________η(均选填“>”“=”“<”)

答案

<   <   <

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