# Recent content by sedaw

thank you !
2. ### Divergence operator in cylindrical & sherical

look for some proof for the formula of the divergence operator in cylindrical & spherical coordinate is there any on the net ? TNX ! the formula here: http://hyperphysics.phy-astr.gsu.edu/hbase/diverg.html
3. ### Negative volume ?

negative volume ??? attached herewith pdf file with the problem and my solution .
4. ### Need help volume calculation .

ok.. thank you very much i am appreciate your help. by the way my picture is V for the uvz axis and not xyz .
5. ### Need help volume calculation .

cotan(t) = cos(t)/sit(t) the limits of integration on u & v simply received from the projection of the region bounded by V on the UV plane -> you can see it circle with radius R=1 . the limits of integration on z: you can see in sketch : 0<=z<=U+V (of course just for u & v that in...
6. ### Need help volume calculation .

attached herewith : the problem with my attempt to solve it .
7. ### The generalization of Newton's 2nd Law to apply to variable mass systems

F = dp/dt = d(mv)/dt = m(dv/dt) + v(dm/dt) = a + v(dm/dt) i dont understand why d(mv)/dt = m(dv/dt) + v(dm/dt) can somone help ? TNX !:smile:

ok tnx ...
9. ### Limit problem calculate

need to calculate lim X->infinity of x*[1/x] , while [] represent floor function . TNX.
10. ### Volume problem

hello ! need to find the volume of V: { x^2+y^2=z , x^4+y^4=1 } i dont know how to set up the triple integral caue i didnt find any way to understand the surface projection on the xy plane . I would appreciate any help ....

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12. ### Problem with integrating factor

what next ? TNX !
13. ### Calculate the limit of the series

hello Dick ! first of all tnx. i cant use l'Hopital's theorem cause n =1,2,3..... so F(n) not differentiable .
14. ### Calculate the limit of the series

need to calculate the limit of the series (cos(a/n))^(n^3) n goes to infinity and a=!0 i try that : e^L L= the limit of (n^3)*ln(cos(a/n)) what now ??? TNX !
15. ### Sum of 1/ln(n)^(ln(n)) from n=3 to infinity?

nope , you are magician , how u did it ? TNX !