Vector Diff. Q: Dot & Cross Prod. Differentiation?

In summary, the conversation discusses the equivalence of differentiation between dot and cross products. It is confirmed that the order of the terms in the equations does not matter, as addition is commutative even with vector elements.
  • #1
sams
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I have a question regarding the dot product and the cross product differentiation. I was wondering whether:
$$\frac{d(\vec{A}.\vec{B})}{du} = \vec{A}. \frac{d\vec{B}}{du} + \frac{d\vec{A}}{du} .\vec{B}$$
is the same as
$$\frac{d(\vec{A}.\vec{B})}{du} = \frac{d\vec{A}}{du} .\vec{B} + \vec{A}. \frac{d\vec{B}}{du}$$

and
$$\frac{d(\vec{A}×\vec{B})}{du} = \vec{A}× \frac{d\vec{B}}{du} + \frac{d\vec{A}}{du} ×\vec{B}$$
is the same as
$$\frac{d(\vec{A}×\vec{B})}{du} = \frac{d\vec{A}}{du} ×\vec{B} + \vec{A}× \frac{d\vec{B}}{du}$$

or not!

Thank you so much for your help...
 
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  • #2
Addition is commutative even with vector elements, so yes, all equalities you wrote hold.
 
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DrClaude said:
Addition is commutative even with vector elements, so yes, all equalities you wrote hold.
Thank you DrClaude for your reply and for your help
 

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

The dot product is a type of multiplication operation that takes two vectors and produces a scalar quantity. It is found by multiplying the corresponding components of the two vectors and then adding them together. The cross product, on the other hand, is a type of multiplication that takes two vectors and produces a third vector that is perpendicular to both of the original vectors.

2. How do you calculate the dot product?

The dot product can be calculated using the formula: A · B = |A| * |B| * cosθ, where A and B are the two vectors and θ is the angle between them. Another way to calculate the dot product is by multiplying the corresponding components of the two vectors and then adding them together.

3. What is the purpose of vector differentiation?

Vector differentiation is used to find the rate of change of a vector with respect to another variable. It is important in many fields of science, such as physics and engineering, where vectors are commonly used to represent quantities with both magnitude and direction.

4. How do you differentiate a vector function?

To differentiate a vector function, each component of the vector is differentiated separately. This can be done using the rules of differentiation, such as the product rule and chain rule. The result is a new vector that represents the rate of change of the original vector function.

5. What is the relationship between vector differentiation and dot and cross product?

The dot and cross product are both types of vector multiplication, and therefore are related to vector differentiation. The dot product can be used to find the rate of change of a vector in the direction of another vector, while the cross product can be used to find the rate of change of a vector perpendicular to both of the original vectors.

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