Cross products vs. dot products

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In summary, cross products and dot products are mathematical operations used when working with vectors. Cross products produce a vector that is orthogonal to the original two, while dot products produce a scalar. Cross products are used to find moments, while dot products are used to calculate work done by a force. Scalar values are always associated with dot products, while vector values are associated with cross products.
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Joyci116
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I have a question regarding cross products and dot products. What is the difference, and are there any similarities? What ARE cross products and what are their functions? What ARE dot products and what are their functions? What do we use them for?

Thank you,

Joyci116
 
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Joyci116 said:
I have a question regarding cross products and dot products. What is the difference, and are there any similarities? What ARE cross products and what are their functions? What ARE dot products and what are their functions? What do we use them for?

Thank you,

Joyci116

Well, first of all, you use cross products and dot products when you work with vectors, and I would say (at least how I convinced myself) they are something made up by mathematicians to make vectors useful.

A cross product between two vectors products another vector that is orthogonal to the original two. For example, cross product can be used to find the moment:

M = r x F

A dot product, on the other hand, between two vectors produces a scalar, basically a number. Dot product can be used to calculate the work done by a force:

W = F d

P.S. The bold letters are vectors, and the unbold ones are scalar.
 
  • #3
So what you are trying to convey is that you multiply with cross products and dot products, but it is WHAT you multiply determines whether it is a dot or cross product? Scalar is always dot and vector is always cross product?
 

FAQ: Cross products vs. dot products

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

A cross product is a mathematical operation between two vectors that results in a vector perpendicular to both vectors. A dot product, on the other hand, is a mathematical operation that results in a scalar quantity.

When should I use a cross product versus a dot product?

A cross product is useful when trying to find a vector that is perpendicular to two given vectors, while a dot product is useful when trying to find the magnitude of one vector in the direction of another.

How do I calculate a cross product and a dot product?

To calculate a cross product, you can use the formula a x b = ||a|| ||b|| sinθ n, where a and b are the two vectors, θ is the angle between them, and n is the unit vector perpendicular to both a and b. To calculate a dot product, you can use the formula a ∙ b = ||a|| ||b|| cosθ, where a and b are the two vectors and θ is the angle between them.

Are there any real-life applications for cross products and dot products?

Yes, both cross products and dot products have various real-life applications. For example, cross products are used in physics to calculate torque and in engineering to calculate the force on a moving object. Dot products are used in physics to calculate work and in computer graphics to determine the angle between two vectors.

Can a cross product and a dot product ever be equal?

No, a cross product and a dot product can never be equal since they result in different quantities - a vector and a scalar, respectively. However, in some cases, the magnitude of the cross product can be equal to the magnitude of the dot product, but their directions will always be different.

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