# Homework Help: Unit Vector

1. May 3, 2012

### Eryk

1. The problem statement, all variables and given/known data

Given vector OP = 2i+3j, OQ = qi+2qj. How can i find the possible value for q?
note that PQ is a unit vector.

2. Relevant equations

Given (p-1)i + (2p-6)j having magnitude 10, find p

3. The attempt at a solution

From the formula, i was told that the unit vector can be obtain by dividing the vector by the modulus it self, however i have no idea how to apply that concept into 2 different vector, since the answer wasnt correct when i tried them. please help me on this, thanks in advanced

2. May 3, 2012

### Staff: Mentor

So what are the coordinates of PQ? You have OP and OQ, so you should be able to find PQ.

Once you have found PQ, figure out what q needs to be so that PQ is a unit vector.

This part -- Given (p-1)i + (2p-6)j having magnitude 10, find p -- is a separate problem, right? How you have presented these problems is confusing.

3. May 4, 2012

### Eryk

it is actually hint given to me as how that im going to solve the q part, where it is also having two vector with one of it having p variable. i have no idea how it works either. as for the PQ, the question doesn`t state whether its P to Q or Q to P. so it is safe for me to take it as P to Q?

4. May 4, 2012

### Staff: Mentor

PQ means from P to Q. If the question asked for the vector from Q to P, they would have specified QP.

5. May 4, 2012

ok, thanks

6. May 4, 2012

### SammyS

Staff Emeritus
By the way, Eryk: Welcome to PF !

7. May 5, 2012

Thanks :)