Calculating Angular Acceleration and Stopping Time for a Rolling Train

[kerbyjonsonjr]

Homework Statement

A toy train rolls around a horizontal 1.8 m diameter track. The coefficient of rolling friction is 0.11.

What is the magnitude of the train's angular acceleration after it is released?
How long does it take the train to stop if it's released with an angular speed of 31 ?

Homework Equations

a=v²/r perhaps

The Attempt at a Solution

I am not even really sure how to begin this problem. I am pretty sure it has something to do with centripetal acceleration but I really just have no idea where to begin. Any help would be great. Thanks!

 

[edgepflow]

Your on the right track (no pun intended).

Can you equate the centrifugal force to the normal rolling friction force?

 

[AdrianMay]

The question deliberately avoids you having to worry about it being a circular track. You just pretend it's a straight track and use circumference=2*pi*radius to convert the distances.