1. Mar 26, 2015

### goonking

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

2. Relevant equations

3. The attempt at a solution
So, I got the answer to be 126 radians BUT my answer was wrong because it was suppose to be NEGATIVE 126 radians. Can someone explain why my answer was suppose to be negative?

2. Mar 27, 2015

### haruspex

The wagon is moving in the +x direction. Which way will the wheels rotate? What is the usual convention for the sign of a rotation in planar co-ordinates?

(That said, I think it could me made clearer that a signed value is wanted, not just a magnitude.)

3. Mar 27, 2015

### goonking

wheels will rotate clockwise.

4. Mar 27, 2015

### haruspex

Yes, and what is usually taken as the positive direction for a rotation in the plane?

5. Mar 27, 2015

### goonking

I thought it didn't matter which direction you set to be positive or negative.

6. Mar 27, 2015

### haruspex

The standard convention, e.g. in polar co-ordinates, is anticlockwise positive.