# Determine the angular velocity and the relative velocity

1. Apr 9, 2013

### Northbysouth

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

Bar OA has a counterclockwise angular velocity ω0 = 1.8 rad/s. Rod BC slides freely through the pivoted collar attached to OA. Determine the angular velocity ωBC of rod BC (positive if counterclockwise, negative if clockwise) and the velocity vrel of collar A relative to rod BC (positive if moving from B to C, negative if it moves from C towards B.

I have attached an image of the question

2. Relevant equations

3. The attempt at a solution

My initial thought was to use:

vA = vo + wXr + vrel

to fins the velocity at A and then use the equation again to solve for wBC from a different point. But I don't know the velocity of A to begin with and I'm confused by what is meant by the relative velocity.

Some classmates said that they used the law of sines to find the length of AB and then broke it up into it's respective components but this doesn't make sense to me.

Any help would be appreciated.

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