急 高分悬赏(条理清晰,解答详细另有加分) 请高手帮忙! 物理竞赛难题! 如何做,为什么?

2025-04-06 16:46:43
推荐回答(3个)
回答1:

答案1.不是;2.83.3%
1.假设二者共轴,手拉轮直径为D,承载轮直径为d,当下拉一次(30cm)时,手拉轮边缘转过的弧长为S=30cm
因二轮角速度相等,所以承载轮边缘转过的弧长为s=Sd/D=10cm
绳子自由端移动s,物体应上升h=s/2=5cm
h≠3mm,所以假设不成立,不是共轴的轮轴。
2.W总=FS=360×0.3J=108J
W有=mgs=3000×10×0.003J=90J
η=W有/W总×%=83.3%

回答2:

手拉轮周长= 150*3.14 =471(mm)
承载轮周长= 50*3.14 =157(mm)
右手下拉一次,承载轮转动距离 =(157*30)/471=10(mm)
重物上升的高度 = 10/2=5(mm)
HCB30型“手拉葫芦”的手拉轮与承载轮是一个共轴的轮轴

回答3:

高手在哪里?我帮顶一个!

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