Showing a vector field is imcompressible

In summary, the conversation discusses the separation of the x, y, and z components of a vector field and whether the non-bold r should be treated as a constant. The solution shows that the numerator of the vector field's fraction is bold faced ##\bf{r}## and the denominator is ##r##, representing the vector and its magnitude respectively. The bold face r should not have been used to represent the magnitude and it is not a constant.
  • #1
question dude
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0

Homework Statement


attachment.php?attachmentid=455997&d=1440616258.jpg


Homework Equations

The Attempt at a Solution



As you can see, the solution is shown just below the question.

Essentially, I don't understand how the x, y and z component of the vector field has been separated because the numerator of the vector field's fraction is: (x^2 + y^2 + z^2)^(1/2)

It seems like they've just taken x^2 out and square rooted it to get 'x', but you can't do that, can you?
 
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  • #3
question dude said:

Homework Statement


attachment.php?attachmentid=455997&d=1440616258.jpg


Homework Equations

The Attempt at a Solution



As you can see, the solution is shown just below the question.

Essentially, I don't understand how the x, y and z component of the vector field has been separated because the numerator of the vector field's fraction is: (x^2 + y^2 + z^2)^(1/2)

It seems like they've just taken x^2 out and square rooted it to get 'x', but you can't do that, can you?

That isn't what they have done. The numerator is bold faced ##\bf{r}## and the denominator is ##r##. The first is the vector and the second its magnitude. r = xi + yj + zk.
 
  • #4
LCKurtz said:
That isn't what they have done. The numerator is bold faced ##\bf{r}## and the denominator is ##r##. The first is the vector and the second its magnitude. r = xi + yj + zk.

Do I treat the non-bold r as a constant?

If sub in bold r, I get:

G = [(x^2 + y^2 + z^2)^0.5 ] / 4*pi*r^3
 
  • #5
question dude said:
Do I treat the non-bold r as a constant?

If sub in bold r, I get:

G = [(x^2 + y^2 + z^2)^0.5 ] / 4*pi*r^3

I just noticed in your graphic under (b) they have ##{\bf r} = \sqrt{x^2+y^2+z^2}## That should not have been a bold face r. The bold face r represents the vector and the plain r its magnitude, which is not constant.
 

What does it mean for a vector field to be incompressible?

An incompressible vector field is one in which the divergence (a measure of the flow of the vector field) is equal to zero at every point. This means that the vector field does not have any sources or sinks, and the amount of fluid entering a given region is equal to the amount leaving that region.

How is the incompressibility of a vector field mathematically represented?

The incompressibility of a vector field is mathematically represented by the divergence of the vector field being equal to zero. This can be written as div(F) = 0, where F is the vector field. This equation is often used in the process of showing a vector field is incompressible.

What are some real-life examples of incompressible vector fields?

Some examples of incompressible vector fields in real life include the flow of air or water through a pipe, the movement of ocean currents, and the flow of blood through our circulatory system. These systems must be incompressible in order to maintain a steady and consistent flow.

How is the incompressibility of a vector field tested or verified?

The incompressibility of a vector field can be tested or verified by using the continuity equation, which states that the rate of change of the fluid density in a given volume is equal to the negative of the divergence of the velocity field at that point. If the continuity equation holds true, then the vector field is incompressible.

What are some applications of incompressible vector fields in science and engineering?

Incompressible vector fields have many applications in various fields of science and engineering. They are used in fluid dynamics to model the flow of fluids, in thermodynamics to study heat transfer, and in electromagnetism to describe the behavior of electric and magnetic fields. Incompressible vector fields are also used in computer graphics to simulate the movement of fluids and in robotics to program the movement of mechanical systems.

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