# Centripital force question

1. Jan 5, 2010

### BoldKnight399

A bicycle wheel has an angular acceleration
of 1.4 rad/s2.
If a point on its rim has a tangential accel-
eration of 49 cm/s2, what is the radius of the
wheel?
Answer in units of m.

I know that there should be some way to relate the angular acceleration and the tangential acceleration but I can't figure it out.

I tried to relate the angular acceleration to angular speed to then find delta theta so then I could plug into S=Rtheta. The only problem is that I don't have the angular speed. I know that there has to be an easy way to do this problem.

3. The attempt at a solution

2. Jan 5, 2010

### tiny-tim

Welcome to PF!

Hail BoldKnight399! Welcome to PF!

(erm … tangential is more-or-less the opposite of centripetal )
cm/s2 = radian/s2 times cm/radian

(just like cm/s = radian/s times cm/radian ).

So what is cm/radian in this case?

3. Jan 5, 2010

### BoldKnight399

knew it had to be simple and I was just missing it. Thank you!

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