isabelmacpherson

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4 years, 116 days

MaplePrimes Activity


These are replies submitted by isabelmacpherson

@Carl Love 

Gosh!  Thank you so much.

@Carl Love 

Thank you so what should the four equations be that I run in the rk program?  I'm having problems getting to grips with it.

@Carl Love Thank you!

@tomleslie 

very helpful!  Sorry, I'm terrible with Maple.

@acer 

thanks

@acer 

Thank you.  Sort of but I wonder if you need to put that it is a spherical coordinate system instead of cartesian or add in r^2*sin(ϕ)?  Also isn't phi between 0 and pi or does that not matter?  

 

https://www.khanacademy.org/math/multivariable-calculus/integrating-multivariable-functions/x786f2022:polar-spherical-cylindrical-coordinates/a/triple-integrals-in-spherical-coordinates

@nm 

Yes because I thought you had to do that to calculate volume in spherical coordinates.

@nm 

okay.  We got different answers though for the mass.

@nm 

Thank you!  I did the below?  Do you think that is wrong?

p:=(r,theta,varphi)->ln(r^2 + theta^2+ varphi^2+1);
   
m:=int(p(r,theta,varphi)*r^2*sin(varphi),r=0..2, theta=0..2*Pi, varphi=0..Pi, numeric = true);
                        m := 92.30127289

m_x:=int(p(r,theta,varphi)*r*sin(varphi)*cos(theta)*r^2*sin(varphi),r=0..2, theta=0..2*Pi, varphi=0..Pi, numeric = true);
                     m_x := -0.05742980812

m_y:=int(p(r,theta,varphi)*r*sin(varphi)*sin(theta)*r^2*sin(varphi),r=0..2, theta=0..2*Pi, varphi=0..Pi, numeric = true);
                      m_y := -14.55618714

m_z:=int(p(r,theta,varphi)*r*cos(varphi)*r^2*sin(varphi),r=0..2, theta=0..2*Pi, varphi=0..Pi, numeric = true);
x_bar:=m_x/m;
                    x_bar := -0.005701810122

y_bar:=m_y/m;
                     y_bar := -0.1822880544

z_bar:=m_z/m;
                     z_bar := 0.7468975636

@acer Thank you!  

Sorry to be stupid but what are those two methods you used?

evalf[6](evalf[15](Int(op(H),epsilon=1e-6,method=_CubaCuhre)));

21351.1

evalf[6](evalf[15](Int(op(H),epsilon=1e-5,method=_CubaDivonne)));

21351.1

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