Vectors and scalar projections

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SUMMARY

The discussion centers on the computation of the scalar projection of vector \( a \) onto the cross product \( a \times b \). The formula used is \( \text{comp}_a(a \times b) = \frac{a \cdot (a \times b)}{|a|} \), which simplifies to zero due to the properties of the dot product and cross product. The conclusion is that the scalar projection is indeed zero, confirming that the vectors \( a \) and \( a \times b \) are orthogonal. Additionally, the discussion highlights the validity of interchanging dot and cross products in a triple scalar product.

PREREQUISITES
  • Understanding of vector operations, specifically dot and cross products.
  • Familiarity with scalar projections in vector calculus.
  • Knowledge of vector orthogonality and its implications.
  • Basic grasp of triple scalar products and their properties.
NEXT STEPS
  • Study the properties of the dot product and cross product in vector algebra.
  • Learn about the geometric interpretation of scalar projections in three-dimensional space.
  • Explore the applications of the triple scalar product in physics and engineering.
  • Investigate advanced topics in vector calculus, such as vector fields and their applications.
USEFUL FOR

Students and professionals in mathematics, physics, and engineering who are looking to deepen their understanding of vector operations and their applications in various fields.

hnnhcmmngs
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Homework Statement



Let a and b be non-zero vectors in space. Determine comp a (a × b).

Homework Equations



comp a (b) = (a ⋅ b)/|a|

The Attempt at a Solution


[/B]
comp a (a × b) = a ⋅ (a × b)/|a| = (a × a) ⋅b/|a| = 0 ⋅ b/|a| = 0
Is this the answer? Or is there more to it?
 
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I don't know if your work is mathematically correct, but what can you say about the direction of the resultant of a x b compared to the direction of a? And what is the dot product of two vectors that have that directional relationship? :smile:
 
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hnnhcmmngs said:

Homework Statement



Let a and b be non-zero vectors in space. Determine comp a (a × b).

Homework Equations



comp a (b) = (a ⋅ b)/|a|

The Attempt at a Solution


[/B]
comp a (a × b) = a ⋅ (a × b)/|a| = (a × a) ⋅b/|a| = 0 ⋅ b/|a| = 0
Is this the answer? Or is there more to it?
Your work is correct assuming that you have proven the formula that you can interchange dot and cross in a triple scalar product:$$
\vec A \cdot \vec B \times \vec C = \vec A \times \vec B \cdot \vec C$$
 
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