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## Homework Statement

I have attached a picture of the diagram of the problem. I am supposed to determine the angular velocities of links OB and BA if the velocity of the slider at the instant shown is 7.5 m/s to the left.

## Homework Equations

Va = Vb + Vab (Velocity of A is equal to the Velocity of B plus the Velocity of A relative to B)

There may be more equations I need. I am not sure.

## The Attempt at a Solution

First, I'm attempting to get the relative positions of A with respect to B and O with respect to B (this is how my teacher solved the problem).

Doing this I get:

Rab = 2.25cos(30) i - 2.25sin(30) j = 1.95i - 1.13j (I feel pretty certain this is correct).

Rob = -1cos(55) - sin(55) = -0.57i - 0.82j (My teacher has positive numbers for this which confuses me because it seems to me that the position of O relative to B on both the X and Y axes is further left and down so it should be negative. Why is my teacher not putting negative signs here?

Va = Vb + Vab

-7.5 i m/s = ??????

And I am stuck here as well. Not sure how to proceed. Thanks for the help.