Understanding the Triple Scalar Product in Vector Calculus

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SUMMARY

The discussion clarifies the distinction between the scalar and vector products in vector calculus, specifically addressing the expressions A x (B dot C) and (A x B) dot C. The first expression is not a valid operation since it attempts to perform a cross product with a scalar, which is undefined. Instead, the scalar triple product is correctly represented as (A x B) dot C or A dot (B x C), both of which are valid operations involving cross and dot products.

PREREQUISITES
  • Understanding of vector operations, specifically cross and dot products.
  • Familiarity with vector notation and properties.
  • Knowledge of scalar and vector quantities in physics and mathematics.
  • Basic principles of vector calculus.
NEXT STEPS
  • Study the properties of the scalar triple product in vector calculus.
  • Learn about the geometric interpretation of cross and dot products.
  • Explore examples of vector calculus problems involving A x (B dot C).
  • Review the definitions and applications of vector and scalar quantities in physics.
USEFUL FOR

Students of mathematics and physics, educators teaching vector calculus, and anyone seeking to deepen their understanding of vector operations and their applications.

brotivation
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Homework Statement



A x (B dot C)

(A x B) dot C

They are vectors.

Homework Equations



A x (B dot C)

(A x B) dot C

The Attempt at a Solution



I know how to do my homework, but I am confused on these formulas.

Is the first formula "A x (B dot C)" the same as the second one? I know the second one is the same as
A dot (B x C).

It doesn't make sense to me. Wouldn't the B dot C become a scalar? So how could A cross with that?
 
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brotivation said:
A x (B dot C)

The first multiplication is not "cross product". The dot product of two vectors is a scalar, and the cross product is defined for two vectors. What you wrote is just a product of A with a scalar.

ehild
 
ehild said:
The first multiplication is not "cross product". The dot product of two vectors is a scalar, and the cross product is defined for two vectors. What you wrote is just a product of A with a scalar.

ehild

So would that mean I do A multiply by (B dot C)?
 
brotivation said:
So would that mean I do A multiply by (B dot C)?
The scalar triple product of for vectors A, B, and C is a combination of a cross-product (also called a vector-product) and a dot-product (also called a scalar-product) .

It's only defined if you do the cross product first.

(A×B)∙C and A∙(B×C) are both defined.

Neither (ABC nor A×(BC) is defined if × denotes the vector product. It's not possible to form a cross-product with a vector and a scalar.
 

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