# Relative angular accelaration

1. Jun 28, 2008

### da_vinci

1. The problem statement, all variables and given/known data
Two solid bodies rotate about mutually perpendicular intersecting axes with constant angular velocities $$\omega_1$$ and $$\omega_2$$. Find the angular velocity and angular accelartion of one body relative to the other.

2. Jun 28, 2008

### Hootenanny

Staff Emeritus
Welcome to PF da_vinci,

It seems that you have missed off two sections of the template...
You need to show some effort in solving the problem yourself before we can help you .

3. Jun 28, 2008

### da_vinci

sorry!!
but i didnt know the concept for the relative angular accelaration..
for relative angular velocities, i think we should use this equation
$$\omega_{12} = \omega_1 - \omega_2$$
am i right??
can somebody help me with this prob? plz?

4. Jun 29, 2008

### Hootenanny

Staff Emeritus
Are you sure about that equation, in particular the sign of the equation?

5. Jun 30, 2008

### da_vinci

i am not too sure of that eqn!!
i dont know how to deal with angular velocity and andular accelarations as vectors.........plz can smone answer this?

6. Jun 30, 2008

### Hootenanny

Staff Emeritus
Okay, we'll start from the beginning. We need to determine the angular velocity of one body with respect to the other. Let us arbitrarily chose to determine the angular velocity of the second object with respect to the first.

From our point of view (POV), the first body is rotating about it's axis of rotation wil an angular velocity of $\omega_1$. However, we need to determine the angular velocity of the axis about the first body from the first body's POV.

Can you do that?

7. Nov 6, 2008

### psychicist

The relative angular velocity can be found using analogy to linear ones, am I correct?

Another thing, since the 2 bodies rotate with constant angular velocity, why is there relative angular acceleration?