Nonuniform circular motion toy train

1. Nov 5, 2008

Jennifer001

1. The problem statement, all variables and given/known data
a toy train rolls around a horizontal 1.0m diameter track. the coeffifient of rolling friction is 0.10

a. what is the magnitude of the train's angular acceleration after it is released
b. how long does it take the train to stop if it's released with an angular speed of 30rpm.

2. Relevant equations

At=r(alpha)
A=v^2/r
Ff=uk*ma=uk*mg

3. The attempt at a solution

i know im suppose to look for the angular acceleration but i dont know what the tangential acceleration is, is there a relationship between centripetal acceleration and tangential .. also i dont know how to include the friction coieff. into an equation..

so i have

2. Nov 6, 2008

tiny-tim

Hi Jennifer001!

For a constant radius, the tangential acceleration is just dv/dt.

And you put the friction into Newton's second law to find the acceleration (or you could just use the work-energy theorem ), exactly as on a straight track.