# Homework Help: Finding the position on a circle.

1. Sep 23, 2015

### astrololo

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

Someone runs on a circle in the direction of a clock. He goes at constant speed. The circle is put in a xy plane that is centered at the origin. The radius is 10 m. At a certain moment he has a speed of (3i + 3j) m/s. Determine the position at this moment. (in vectorial notation)
2. Relevant equations
a^2+b^2=c^2

3. The attempt at a solution

3^2 + 3^2 = 18
4.24
Square root ( 18) = 4.24 m/s

Last question for tonight, I promise.

2. Sep 23, 2015

### phinds

3. Sep 23, 2015

### astrololo

Yeah, but we need to find the lenght of the vector of the speed to be able to find the position, no ?

4. Sep 23, 2015

### phinds

What do i and j represent?

5. Sep 23, 2015

### astrololo

Oh, IM really sorry. i and j are vectorial units.

6. Sep 23, 2015

### phinds

units of what? What I'm trying to get here is for you to specify more clearly just what it is that you know. You really should draw a picture.

7. Sep 23, 2015

### astrololo

It's m/s

8. Sep 23, 2015

### phinds

We're really getting nowwhere here. Draw a picture showing what you know and what you are tying to find out.