Solution: Plotting Mathematica Homework w/ Recursion Limit Error

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The discussion revolves around resolving a recursion limit error encountered while plotting a Mathematica homework problem involving electric field equations. The user initially presented their equations for x, y, and z based on the electric field formula but faced a recursion limit issue. A suggestion was made to rename the variables to avoid conflicts, as the same variable names were used for both the function and the input. After implementing the changes, the user successfully obtained a plot, although they noted that the output appeared unusual. The conversation highlights the importance of variable naming in programming to prevent errors.
Ashley1nOnly
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Homework Statement


upload_2018-9-12_15-48-13.png


Homework Equations


E= kq/r^2 * r-hat

where q= +/-(1.6*10^-19)

The Attempt at a Solution


x=

(1.6*10^-19)*x/(x^2+y^2+(z+1)^2)^(3/2) - (1.6*10^-19)*x/(x^2+y^2+(z-1)^2)^(3/2)y=

(1.6*10^-19)*y/(x^2+y^2+(z+1)^2)^(3/2) - (1.6*10^-19)*y/(x^2+y^2+(z-1)^2)^(3/2)

z=

(1.6*10^-19)*(z+1)/(x^2+y^2+(z+1)^2)^(3/2) - (1.6*10^-19)*(z-1)/(x^2+y^2+(z-1)^2)^(3/2)ContourPlot3D[{x,y,z},{x,-5,5},{y,-5,5},{z,-5,5}]

This should work but it is giving me a recursion limit error. I know that the math (well at least I think) is correct.

Any suggestions on how to fix the error?
 

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Ashley1nOnly said:

Homework Statement


View attachment 230602

Homework Equations


E= kq/r^2 * r-hat

where q= +/-(1.6*10^-19)

The Attempt at a Solution


x=

(1.6*10^-19)*x/(x^2+y^2+(z+1)^2)^(3/2) - (1.6*10^-19)*x/(x^2+y^2+(z-1)^2)^(3/2)y=

(1.6*10^-19)*y/(x^2+y^2+(z+1)^2)^(3/2) - (1.6*10^-19)*y/(x^2+y^2+(z-1)^2)^(3/2)

z=

(1.6*10^-19)*(z+1)/(x^2+y^2+(z+1)^2)^(3/2) - (1.6*10^-19)*(z-1)/(x^2+y^2+(z-1)^2)^(3/2)ContourPlot3D[{x,y,z},{x,-5,5},{y,-5,5},{z,-5,5}]

This should work but it is giving me a recursion limit error. I know that the math (well at least I think) is correct.

Any suggestions on how to fix the error?

I haven't checked your physics; the rest of this reply is solely involving the recursion limit error.

You are using your x, y, and z variables for different things in different places. Try changing the names of your variables appropriately.

For example, right now you have
x = a function of x (and also y and z).

Try changing that to

x1 = a function of x (and also y and z)

or some other variable name that makes more sense.
 
Thanks, that worked. It gave me an answer with the expected lines but it does look funny.

upload_2018-9-12_18-15-33.png
 

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The book claims the answer is that all the magnitudes are the same because "the gravitational force on the penguin is the same". I'm having trouble understanding this. I thought the buoyant force was equal to the weight of the fluid displaced. Weight depends on mass which depends on density. Therefore, due to the differing densities the buoyant force will be different in each case? Is this incorrect?

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