# 21.1 Scalar Product Properties | Summary and Q&A

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June 2, 2017
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MIT OpenCourseWare
21.1 Scalar Product Properties

## TL;DR

Introduction to the scalar product and dot product, which are mathematical operations used to determine the parallel components of vectors in different dimensions.

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### Q: What is the purpose of generalizing the concept of work to handle multidimensional motion?

Generalizing the concept of work to handle multidimensional motion allows us to calculate the work done on an object that moves in more than one direction, taking into account its displacement in different dimensions.

### Q: How is the scalar product of two vectors defined?

The scalar product of two vectors is defined as the magnitude of one vector multiplied by the amount of the other vector that is parallel to the first vector. It can be positive or negative, depending on the angle between the vectors.

### Q: What is the geometric interpretation of the dot product?

Geometrically, the dot product represents the parallel components of two vectors. It is equal to the magnitude of one vector multiplied by the cosine of the angle between the vectors.

### Q: What are the two crucial rules for dot products?

The first rule states that multiplying a vector by a scalar and then taking the dot product is equivalent to multiplying the dot product by the scalar. The second rule states that vector addition distributes over vector multiplication by the dot product.

## Summary & Key Takeaways

• The video introduces the concept of work in motion and the need to generalize it to handle multidimensional motion.

• The scalar product is defined as the magnitude of one vector multiplied by the amount of another vector that is parallel to the first vector.

• The dot product is defined as the magnitude of one vector multiplied by the cosine of the angle between two vectors.