Cross Product Confusion: Solving UxV

In summary, the conversation discusses the cross product and how to calculate it using the given equations for U and V. The final equation for UxV is provided and the conversation concludes with a solution for the i component of UxV.
  • #1
likephysics
636
2
I was reading div grad curl and all that. Couldn't get something basic - cross product.

U = iux + k df/dx (ux)
V = jvy + k df/dy (vy)

UxV = [ -i df/dx - j df/dy + k] uxvy

can't figure out how to get U x V.
 
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  • #2
Hi likephysics! :smile:

(have a curly d: ∂ and try using the X2 tag just above the Reply box :wink:)
likephysics said:
I was reading div grad curl and all that. Couldn't get something basic - cross product.

U = iux + k df/dx (ux)
V = jvy + k df/dy (vy)

UxV = [ -i df/dx - j df/dy + k] uxvy

can't figure out how to get U x V.

(Let's ignore the common factor, uxvy)

The i component of UxV is UjVk - VjUk, = 0 - ∂f/∂x.

Can you do the others now? :smile:
 
  • #3
Thanks a bunch. Now I feel less stupid. yay!
 

1. What is a cross product and how is it used in solving UxV?

A cross product is a mathematical operation that takes two vectors and produces a new vector that is perpendicular to both of the original vectors. In solving UxV, the cross product is used to find the vector that is perpendicular to both the U and V vectors, which can be helpful in solving problems involving forces or motion in three-dimensional space.

2. What is the difference between a dot product and a cross product?

While the cross product produces a vector, the dot product produces a scalar (a single number). Additionally, the dot product is commutative, meaning that the order of the vectors does not matter, while the cross product is not commutative. The dot product measures the similarity or alignment between two vectors, while the cross product measures the perpendicularity between two vectors.

3. How do you calculate the cross product of two vectors?

To calculate the cross product of two vectors, you first need to determine the direction of the resulting vector. This can be done by using the "right hand rule" or by using the determinant of a 3x3 matrix. Next, you will need to calculate the magnitude of the resulting vector using the formula ||u x v|| = ||u|| ||v|| sinθ, where θ is the angle between the two vectors. Finally, you can use the direction and magnitude to write out the resulting vector in component form.

4. What are some real-world applications of cross products?

Cross products have many real-world applications, such as in physics for calculating torque and angular momentum, in engineering for finding the direction of a force acting on a structure, and in computer graphics for creating 3D graphics and animations. They are also used in navigation and aviation for determining the direction and speed of an object.

5. Can you solve UxV without using the cross product?

It is possible to solve UxV without using the cross product, but it may require more complex equations and calculations. The cross product is a useful tool for quickly finding the perpendicular vector and can simplify problem-solving in three-dimensional space. However, it is not the only method and may not be necessary in all situations.

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