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Components using partial derivatives

  • #1
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here is the question:
http://i44.tinypic.com/xe53tc.gif

here is the solution:
http://i43.tinypic.com/2nuokfq.gif
my first question regarding this whole thing is.
why when the doing the partial derivative by "r" we dont multiply by minus
the formula says (minus derivative)
but all they do is making a derivative without multiplying by minus?
 
Last edited:

Answers and Replies

  • #2
tiny-tim
Science Advisor
Homework Helper
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Hi transgalactic! :smile:
here is the question:
http://i43.tinypic.com/2nuokfq.jpg

here is the solution:
http://i43.tinypic.com/2nuokfq.gif
erm :redface: … they're the same :confused:

get some sleep! :zzz:​
why when the doing the partial derivative by "r" we dont multiply by minus
the formula says (minus derivative)
but all they do is making a derivative without multiplying by minus?
?? :confused: but they have multiplied by the minus …

∂/∂r (1/r2) = -2/r3, and ∂/∂θ (cosθ) = -sinθ :smile:
 
  • #3
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but we are doing a derivative by 'r'(partial derivative)
we dont touch [tex]\theta [/tex] ,its constant
 
Last edited:
  • #4
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0
i changed the original post
now its ok
 
  • #5
tiny-tim
Science Advisor
Homework Helper
25,832
249
but we are doing a derivative by 'r'(partial derivative)
we dont touch [tex]\theta [/tex] ,its constant
ok, but still ∂/∂r (1/r2) = -2/r3 :smile:
 
  • #6
1,395
0
thanks
 

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