What is the answer to the product of two vectors with r=xi+yj+zk?

In summary, the dot product of two vectors a and b is defined as a1b1 + a2b2 + a3b3, where a and b are represented as (a1,a2,a3) and (b1,b2,b3) respectively. The dot product of a vector with itself, such as k.k, is equal to 0. In the given scenario, the vector r is represented as xi + yj + zk, and the dot product of r with itself is equal to z.
  • #1
gtfitzpatrick
379
0

Homework Statement



r.k where r=xi+yj+zk

The Attempt at a Solution



is the answer to this just z or is it x+y
 
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  • #2
Well, why do you think it is either of the answers you quote?

What is the definition of the dot product of two vectors?
 
  • #3
Dot product of 2 vectors a.b is a1b1+a2b2+a3c3?
 
  • #4
i think k.k = 0
 
  • #5
gtfitzpatrick said:
Dot product of 2 vectors a.b is a1b1+a2b2+a3c3?
Ok, good. So, presumably, this definition is for two vectors a=(a1,a2,a3) and b=(b1,b2,b3). Can you write your two vectors in this form?

gtfitzpatrick said:
i think k.k = 0
Hold on.. this doesn't agree with what you stated above. Have another think...
 
  • #6
xi+yj+zk.k so this is x0+y0+z1 = z?
 
  • #7
Yup, that's correct.
 
  • #8
thanks a mill
 
  • #9
No problem!
 

1. What is a product of two vectors?

The product of two vectors is a mathematical operation that results in a scalar, vector, or tensor quantity. It is used to determine the relationship between two vectors in terms of magnitude and direction.

2. What are the different types of products of two vectors?

There are three types of products of two vectors: dot product, cross product, and tensor product. The dot product results in a scalar quantity, the cross product results in a vector quantity, and the tensor product results in a tensor quantity.

3. How do you calculate the dot product of two vectors?

The dot product of two vectors is calculated by multiplying the magnitude of one vector by the magnitude of the projection of the other vector onto the first vector. This can also be represented as the sum of the products of each component of the two vectors.

4. What is the purpose of the cross product of two vectors?

The cross product of two vectors is used to determine the direction of the perpendicular vector to the plane formed by the two original vectors. It is also used in calculating torque and determining the area of a parallelogram.

5. Can the product of two vectors be negative?

Yes, the product of two vectors can be negative. This is dependent on the angle between the two vectors, and can result in a negative scalar or a negative direction for the resulting vector.

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