Homework Help: Vector Problem

1. Oct 23, 2007

janhen200

I need help on this vector problem. We haven't started yet, but this was one of the problems on the syllabus.

Your home is 15.0 km at a direction 40 degrees northwest. If you walked 10.0 km north, in what direction and distance would you have to walk to get home?

Your help will be greatly appreciated

2. Oct 23, 2007

pooface

Welcome to Physicsforums! hope you enjoy your stay.

A vector is a quantity that has a magnitude(like 15 km) and direction (like north or south or an angle such as 40deg).

A good place is always to start with a diagram so you can visually see what is going on.

Your home is 15 km away but 40 degrees north OF west. Can you draw this?

3. Oct 26, 2007

janhen200

so far, i've done this and i'm not sure whether or not im correct.

l \
l \
l \ --->15 km
l \
l___\ ----> 40 degrees

sorry, im really bad at making diagrams on the computer. It just wanst coming out right. Basically i mae a triangle, with a hypotenuse of 15 and one of the angles (the one opposite the hypotenuse) is 40 degrees.

Last edited: Oct 26, 2007
4. Oct 26, 2007

pooface

Looks correct to me. However, it is not teh angle opposite to the hypotenuse. it is the angle with the x axis and hypotenuse.

Now you walk north 10km. What direction and distance do you walk to reach home?

5. Oct 26, 2007

janhen200

I used pythagorean theorem.

a=10
b=x
c=15

10^2 + b^2= 15^2

b=11.1
He needs to walk 11.1 km east to get home

Please let me know whether this is right or wrong.

6. Oct 26, 2007

pooface

yea it is right. Try to keep more decimal places. 11.1 is quite different than 11.18.

7. Oct 26, 2007

janhen200

Ok, thanks alot. You've been a great help.