How do you check if a vector is constant?

[kthouz]

Can someone explain me how check if a vector is a constant vector?

 

[disregardthat]

You have to define your terms. What is a constant vector, i.e. how is it defined?

 

[HallsofIvy]

You check if it is a vector, you check if it is constant. What more do you want? Perhaps if you gave an example of the typ of problem you are trying to do it would help.

 

[kthouz]

've been two perpendicular vectors r and v. r=coswi + sinwj where w is a constant and i and j are unit vectors.
The problem is to show first that v is perpendicular to r and then show that r x v is a constant vector. (here x is the cross product)

 

[HallsofIvy]

Okay, so you are given r= cos(w)i+ sin(w)j. You are also "given" v? What is v? Showing that v is perpendicular to r (for whatever v you are given) should be easy. Just take the dot product. As for a constant vector, so far you haven't mentioned any variable! Are you sure it wasn't r= cos(wt)i+ sin(wt)j where t is the independent variable?

It's really very difficult to help you if you don't tell use precisely what the problem is!