17提
iamapen2022-10-04 11:39:541条回答
17提
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- 月亮qq 共回答了20个问题
|采纳率90% - (1)中学生跳起后重心升高 h=2.70-2.25m=0.45m…①
根据机械能守恒定律 1/2mv2=mgh…②
解得 v=√2gh=3m/s…③
(2)根据牛顿定律 F-mg=ma…④
运动学规律v=at …⑤
解得F=m(g+v/t)=1400N
答:
(1)他刚离地跳起时的速度大小是3m/s.
(2)他与地面间的平均作用力的大小是1400N.
望采纳~~ - 1年前
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