## 5 thoughts on “4.10”

When finding the velocity at point O, could we have instead used the velocity at E (v) and the position vector from E to O? Thanks

1. tutorpaul says:

Yes! $\vec{V}_O = \vec{V}_E + \vec{\omega} \times \vec{r}_{EO}$ would work fine!

2. blake.wallace95 says:

This is the exact same problem from the 11th edition

3. beaujakob says:

How do we know the angular velocity vector is in the negative k direction and not positive?

1. tutorpaul says:

At the onset of the problem we don't know anything about the direction of the angular velocity. What I did in this problem (and other planar rotation problems) is assume a direction of rotation, and let the numbers tell me if I'm right or wrong. In this problem there are no numbers, but if you can see based on the math that the actual direction of the angular velocity of the body will be dependent on the quantities for $v$ and $v_a$.