# Angular speed

1. Feb 1, 2006

### angel_romano

If a wheel accelerates from rest at 1.0 m/s^2 and I need to find the instantaneous angular speed of the wheel at .10s would this be the proper formula:

final angular speed=initial angular speed + angular acceleration(change in time)

When I use this formula, it comes out to .10 rad/s which just seems to simple.

2. Feb 1, 2006

### Valhalla

Well, you state the wheel accelerates from rest at 1.0m/s^2. m/s^2 is a measurement of linear acceleration not angular acceleration.

3. Feb 1, 2006

### angel_romano

But how does the angular acceleration fit in then?

I have linear formulas, but I'm not sure which one I would use.

4. Feb 1, 2006

### andrewchang

$$\alpha r = a$$

5. Feb 2, 2006

### andrevdh

With a little bit of reasoning one could solve it with basic knowledge...
Via the linear acceleration one could calculate the linear velocity of the centre of the wheel after the given time. At this stage one could reason that the earth is moving with the same speed in the opposite direction while the wheel is standing still, hence the speed of rotation of the wheel since it is in contact with the earth.