Problem involving dot and cross product

In summary, the conversation involves a problem that requires finding the dot and cross product of two vectors and using them to solve for a specific equation. The steps to solve the problem include taking the dot product with one of the vectors, getting the resulting equation into a specific form, and correcting a typo in the given equation. The individual is also advised to try turning the problem into a concrete example before generalizing it.
  • #1
matthew1
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0
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  • #2
matthew1 said:

Homework Statement



https://www.dropbox.com/s/8l90hahznjlv9d0/vector problem.png?dl=0

Homework Equations



Dot and Cross product

The Attempt at a Solution



although I know the dot and cross product, I'm not sure what I'm being asked or how to proceed? any help?[/B]

Have you tried to turn it into a concrete example than generalizing it?

The problem wants you to find a dot b and a cross b then use them to show the equation for a.
 
Last edited:
  • #3
Do as the steps ask.
In (a), take the dot product with ##\vec a## on each side of the given equation. What equation results? Then get that equation into the form ##\vec a.\vec b =##.

The note at the end has a typo. Are you familiar with the equation that was intended?
 

1. What is the difference between dot and cross product?

The dot product, also known as the scalar product, is a mathematical operation that takes two vectors and returns a scalar quantity. It is calculated by multiplying the magnitudes of the two vectors and the cosine of the angle between them. The cross product, also known as the vector product, is a mathematical operation that takes two vectors and returns a vector perpendicular to both of the original vectors. It is calculated by multiplying the magnitudes of the two vectors, the sine of the angle between them, and a unit vector in the direction perpendicular to the two vectors.

2. When should I use the dot product and when should I use the cross product?

The dot product is useful for calculating the angle between two vectors, determining if two vectors are perpendicular, and for projecting one vector onto another. The cross product is useful for calculating the area of a parallelogram formed by two vectors, determining the direction of a resulting vector in a 3D space, and for calculating torque in physics.

3. Can the dot product and cross product be applied to more than two dimensions?

Yes, both the dot product and cross product can be extended to higher dimensions. However, the cross product is only defined for 3D vectors, while the dot product can be extended to any number of dimensions.

4. Is the dot product commutative? Is the cross product commutative?

The dot product is commutative, meaning the order of the vectors does not matter. This is because the dot product only results in a scalar quantity. The cross product, on the other hand, is not commutative. The order of the vectors matters because the cross product results in a vector perpendicular to both of the original vectors, and the order of the vectors affects the direction of this resulting vector.

5. What are some real-life applications of the dot and cross product?

The dot product is commonly used in physics and engineering for calculating work, energy, and power. It is also used in computer graphics for lighting and shading calculations. The cross product is used in physics for calculating torque, in engineering for calculating moments of inertia, and in mathematics for calculating determinants.

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