What is this vector problem asking?

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In summary, the conversation discusses finding the set of all points (x, y, z) that satisfy the equation for the magnitude of r - r0 being equal to 4. It is determined that this equation represents a sphere with radius 4, centered at the point r0. The vector and algebraic equations for this sphere are also discussed.
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reddawg
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Homework Statement


If r = <x, y, z> and r0 = <x0, y0, z0>, describe the set of all points (x, y, z) such that the magnitude of r – r0 = 4.


Homework Equations





The Attempt at a Solution


I don't know what this problem is asking to even attempt a possible solution. Please help?
 
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  • #2
If you start by trying r0 = <0, 0, 0> does that help? Can you see what that means for r?
 
  • #3
Trying that I get x2 + y2 + z2 = 16 after finding the magnitude, but I still can't see what that does to r.
 
  • #4
What kind of object does that equation describe?
 
  • #5
What if you lose the z and reduce it to two dimensions: $$x^2 + y^2 = 16$$?
 
  • #6
Including the z^2, the equation represents a sphere with radius 4. Without the z^2 it's a circle.
 
  • #7
Good. And, if r_0 is the point <x0, y0, z0>?
 
  • #8
I'm guessing that the reverse would be true making the components of r_0 negative, however squaring those would make that irrelevant. This is where I'm not following.
 
  • #9
Think geometrically.
 
  • #10
So r_0 is the center/origin of the sphere/circle?
 
  • #11
Yes, that's it. $$|r - r_0| = 4$$ is the vector equation for a sphere of radius 4, centred at r0.

It's equivalent to $$(x-x_0)^2 + (y-y_0)^2 + (z-z_0)^2 = 16$$
 
  • #12
Wow I way over thought this.

Thanks PeroK.
 

1. What is a vector problem?

A vector problem is a mathematical question that involves the use of vectors, which are mathematical quantities that have both magnitude and direction. These problems often involve calculating the position, velocity, or acceleration of an object in a specific direction.

2. How do I know if a problem involves vectors?

A problem typically involves vectors if it mentions quantities such as displacement, velocity, or acceleration, which all have direction associated with them. Additionally, visual representations of the problem may include arrows or diagrams indicating the direction and magnitude of the vectors involved.

3. What are some common types of vector problems?

Some common types of vector problems include calculating the resultant vector when adding or subtracting two or more vectors, finding the angle between two vectors, and determining the components of a vector in a given direction.

4. How do I solve a vector problem?

To solve a vector problem, it is important to first understand the given information and what is being asked. Then, use mathematical operations such as addition, subtraction, and trigonometric functions to manipulate the vectors and find the desired solution. It may also be helpful to draw a diagram to visualize the problem and the vectors involved.

5. What are some tips for solving vector problems?

Some tips for solving vector problems include breaking down complex problems into smaller, more manageable parts, using vector components to simplify calculations, and checking your answer by considering the magnitude and direction of the resultant vector. It is also important to pay attention to units and use vector notation correctly throughout the problem.

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