# Mechanics: Degrees of freedom (extremely simple)

1. Jun 4, 2009

### tomedj

1. The problem statement, all variables and given/known data
A particle slides along a wire which is rotating at a constant angular velocity w. In polar coordinates the equation of constraint is :

theta' - w = 0 OR theta - wt = 0. *

What is the equation of constraint in cartesian coordinates?

2. Relevant equations

3. The attempt at a solution
Is it:

wx - y' = 0 * ???

*all primes are derivatives wrt t.

Thanks in advance, I know it's basic but I've hit a wall and have been looking at it for way longer than is healthy...
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

2. Jun 4, 2009

### cepheid

Staff Emeritus
Can't you just do a coordinate transformation from polar to cartesian? How is theta defined in terms of x and y?

3. Jun 5, 2009

### tomedj

sin(theta) = y/r and cos(theta) = x/r etc.

It's not that simple is it? I could cos or sin both sides of theta = wt but the I'll get something that looks like:

y/r = sin(wt)...