过程和受力示意图11题
来源:学生作业帮 编辑:搜狗做题网作业帮 分类:物理作业 时间:2024/08/08 15:16:39
![](http://img.wesiedu.com/upload/9/0f/90fa08638eae6aa52821e4ab8004713e.jpg)
![过程和受力示意图11题](/uploads/image/z/5596761-57-1.jpg?t=%E8%BF%87%E7%A8%8B%E5%92%8C%E5%8F%97%E5%8A%9B%E7%A4%BA%E6%84%8F%E5%9B%BE11%E9%A2%98)
解题思路: (1)设滑轮C对滑轮B施加的力为FB,则FB= 1/2(G+G动), 人的拉力F=1/2 (FB+G动),推导出F=1/2 (1/2 (G+G动)+G动)=1/4 G+3/4 G动,根据机械效率公式得出效率比,解得动滑轮重; (2)求出拉力F,和拉力端速度,利用P=Fv求功率; (3)求出压力,受力面积相同,利用压强公式求比值
解题过程:
1CBFBFB=
(动F=
(动F=
(G+G)动=
G, 当提升物体时,GA+
动 当提升物体时,GM+
动 由题知:
:=8:7
, 解得:动; ()动 F2=
G=
×420N=150N物×0.2m/s=0.8m/s, P=F2v=150NF1=
G=
×720N=225N::450
得: p1p2= F压1F压2=5:6
解题过程:
1CBFBFB=
![](http://img.wesiedu.com/upload/f/63/f63f68073d65dfcffeeabd9d85762ce4.png)
![](http://img.wesiedu.com/upload/f/63/f63f68073d65dfcffeeabd9d85762ce4.png)
![](http://img.wesiedu.com/upload/f/63/f63f68073d65dfcffeeabd9d85762ce4.png)
![](http://img.wesiedu.com/upload/b/a8/ba85bee21a5519ac0757ef9cf0ece009.png)
![](http://img.wesiedu.com/upload/d/7f/d7f80eb5e5ac2a70c98b699eb08d8fd1.png)
![](http://img.wesiedu.com/upload/d/7f/d7f80eb5e5ac2a70c98b699eb08d8fd1.png)
![](http://img.wesiedu.com/upload/c/a0/ca0728a0c9a9ed6d8f14f74b803ff165.png)
![](http://img.wesiedu.com/upload/a/05/a05f7d145eb46f5d899d83b70168fb3f.png)
![](http://img.wesiedu.com/upload/b/a8/ba85bee21a5519ac0757ef9cf0ece009.png)
![](http://img.wesiedu.com/upload/b/a8/ba85bee21a5519ac0757ef9cf0ece009.png)
![](http://img.wesiedu.com/upload/b/a8/ba85bee21a5519ac0757ef9cf0ece009.png)
![](http://img.wesiedu.com/upload/b/a8/ba85bee21a5519ac0757ef9cf0ece009.png)
![](http://img.wesiedu.com/upload/f/0e/f0ee9bc69b84dbf629353a46157d8b19.png)