【求助】大家可不可以帮我看看这两道数学题（已解决，谢谢大家热心帮忙）

the first one supposed to belong to high school. u can just assume all the mass is at the gravity center(center point of the container).

引用

最初由 Novia 发布
calc?大学的?.....还有和物理联系的啊.......偶8会.............=v=.........

I think these are just Cal AB problems. In college more often than not you use Cal to solve specific problems, rather than using specific problem to learn Cal.

第二题的A是不是把v(r)从R到r integrate了，除以（R-r）？

Not so sure about it. I believe you do the cross sectional area for this problem. Probably my advice is all wrong.
First, there is work to pump all the water to the top of the cylinder. This is the hard part. We use cross sectional area. I don't remember how since the cylinder is on the side. Once you get the cross sectional area. You do an integral from 0 to some number for the function of the cross sectional area times 1000 times g and y. You integrate the function and then you get the work.

Work = mgh. From the density, we get mass is 1000 kg.
Second, once the water is pump to the top. We have to pump it 1 meters high more. This is the easy part.
You just multiply - 1000 kg times g times 1 meter and that's the work

Last, you add the work up. the work to lift is 1 meters and the work to pump water to the top.
Hoope this helps...

引用

最初由 pojen 发布
第一題:

將水塔切成水平的鐵板狀, 移動每一張鐵板所需的能量可輕易算出.
ps. 記得將鐵板寬用畢氏定理改寫為 function of 深.

第二題:

pojen 建議你畫一下圖, V(r) against r. 平均值應不難看出要如何算.

物理理解算法:
1.) 求 flux
2.) 除以其流動切面積

祝好運~

偶笨。。。。不是很懂。。。可以说详细一点吗？嘻嘻嘻。。。

第一題:

將水塔切成水平的鐵板狀, 移動每一張鐵板所需的能量可輕易算出.
ps. 記得將鐵板寬用畢氏定理改寫為 function of 深.

第二題:

pojen 建議你畫一下圖, V(r) against r. 平均值應不難看出要如何算.

物理理解算法:
1.) 求 flux
2.) 除以其流動切面積

祝好運~