# finding the norm of a scalar product

• Sep 13th 2010, 10:43 AM
slapmaxwell1
finding the norm of a scalar product
I jus had a quick question. in my study guide I am asked to find the norm of a scalar product? this would simply be |3V|? where im actually getting the magnitude of the scalar? is this what the question is asking me to do? I jus wanted to make sure i had it right.

and i had one more question, the next question is asking me to find the magnitude of the projection. so could i write this representation as follows? |proj of j onto u| =
|(u dot j/|v|^2) U|? thanks in advance.
• Sep 13th 2010, 11:56 AM
HallsofIvy
Quote:

Originally Posted by slapmaxwell1
I jus had a quick question. in my study guide I am asked to find the norm of a scalar product? this would simply be |3V|? where im actually getting the magnitude of the scalar? is this what the question is asking me to do? I jus wanted to make sure i had it right.

Yes, that is correct. If $\displaystyle \alpha$ is a scalar and V is a vector then the norm of $\displaystyle \alpha V$ is $\displaystyle |\alpha V|$ which is also equal to $\displaystyle |\alpha||V|$.

Quote:

and i had one more question, the next question is asking me to find the magnitude of the projection. so could i write this representation as follows? |proj of j onto u| =
|(u dot j/|v|^2) U|? thanks in advance.
I'm not sure I understand your notation. Is U the same as u? What is j? I think perhaps you meant |(u dot v/|v|^2)u|
• Sep 16th 2010, 09:56 AM
slapmaxwell1
sorry about that i did screw up the notation a bit, and i got the problem wrong on my test because of it. i will post the problems i got wrong this evening. thanks for your help with the other problems..I got an A on my first exam!!! :O)