True or False: Magnitude (v+v) = 2*Magnitude (v)

[Mdhiggenz]

Homework Statement

So I took my calc 3 exam today and had this question

true or false

magnitude ( v+v) = 2*magnitude( v)

I put true.

Thoughts?

Homework Equations

The Attempt at a Solution

 

[LCKurtz]

You got it correct. Were you just guessing?

 

[Mdhiggenz]

No I did a problem where I had to solve for K in the magnitude give the value of v. Pretty much I took k from the magnitude and solved for it. So I was hoping the same thing applied here.

 

[skiller]

You got it correct.

Really? I don't see how this is correct.

 

[LCKurtz]

Really? I don't see how this is correct.

If $\vec v = \langle a,b,c\rangle$ what do you get for $|\vec v|$ and $|2\vec v|$?

 

[skiller]

If $\vec v = \langle a,b,c\rangle$ what do you get for $|\vec v|$ and $|2\vec v|$?

Sorry, of course it's correct.

I was having a senile moment when I was imagining the two vectors weren't the same! D'oh!

 

[LCKurtz]

Sorry, of course it's correct.

I was having a senile moment when I was imagining the two vectors weren't the same! D'oh!

Don't feel to bad about that. My first reaction was the same because I was expecting the question to read u+v since, in my opinion, that would have been a better question. Only after I started my reply did I realize the OP had v+v.

 

[vela]

Sorry, of course it's correct.

I was having a senile moment when I was imagining the two vectors weren't the same! D'oh!

Did the same thing here.

 

[skiller]

Don't feel to bad about that. My first reaction was the same because I was expecting the question to read u+v since, in my opinion, that would have been a better question. Only after I started my reply did I realize the OP had v+v.

Did the same thing here.

I obviously need to learn to read twice before posting. Something which you two are obviously better at than me!

 

[Mark44]

If v happened to be perpendicular to itself, the original statement wouldn't be true.

(The zero vector not included, of course.)

 

[skiller]

If v happened to be perpendicular to itself, the original statement wouldn't be true.

(The zero vector not included, of course.)

Now you've lost me!

 

[Mark44]

Math humor...

A nonzero vector can't be perpendicular to itself.

 

[LCKurtz]

Math humor...

A nonzero vector can't be perpendicular to itself.

What if it's bent?