請數學高手指教, 小弟真係唔識做..

👨🏻‍🏫 學術台數學

chung

2008-01-28 4:18 am

http://www.physics.hku.hk/~phys1415/HW1-v2.pdf

第五條...

請指教..

更新1:

myisland8132 , 介唔介意講多小小.. i want to learn more .. how about the last part of b , ds=dsn of

更新2:

do we need to use cross product of JxN

回答 (1)

myisland8132

2008-01-28 6:46 am

✔ 最佳答案

n=r outward normal
F.n=kr^n
ds=r^2sinθdθdφ
∫∫f.n ds
=∫∫ka^n A^2sinθdθdφ
=4πk(A^n+2)
the second part is 0 since F*n=0

2008-01-28 15:39:48 補充：
do we need to use cross product of JxN 應該不需要﹐因為F*n與n垂直

2008-01-28 15:40:36 補充：
F*n=0 打錯了

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