Centripetal Acceleration HELP

1. Nov 13, 2007

Sucks@Physics

What is the centripetal acceleration of a point on the perimeter of a bicycle wheel of diameter 70 cm when the bike is moving 7.0m/s?

I thought the formula was v^2/r =ac

But when I do that i get 1.4m/s^2 and it is not the right answer. Can someone tell me what I'm doing wrong, or if I've used the wrong formula? Thanks

2. Nov 13, 2007

Staff: Mentor

Realize that the diameter is given in cm. Change to meters.

3. Nov 13, 2007

Sucks@Physics

I did. (7m/s)^2/.35m = 140m/s

4. Nov 13, 2007

Sucks@Physics

Sorry that was supposed to be 1.4x10^2 in the first post

5. Nov 13, 2007

Staff: Mentor

I don't see anything wrong with that answer, assuming you gave proper units.