What is the acceleration of a toy car rolling down a ramp at a 20 degree angle?

[fk378]

Homework Statement

A toy car has a total mass of 50 g, and rolls on freely spinning wheels, each of which can be modeled as a uniform disk of mass 1 g, and radius 2mm. What is the acceleration, a, of this toy car when it rolls without slipping down a ramp tilted at an angle of 20 degrees to the horizontal? By what factor is the toy car faster or slower than a frictionless block of the same total mass, ie what is a_car/a_frictionless?

Homework Equations

F=ma
velocity_center of mass=wr (w is angular velocity, r is radius)

The Attempt at a Solution

I don't know how to start this...how do you find the acceleration?

 

[glueball8]

This is like IPhO 2002 problem #3, I don't get it... maybe the solution for it will help?

http://www.jyu.fi/kastdk/olympiads/

 

[fk378]

I don't see a link for the solution for that problem on the site you posted...I see the question, though. Can you send me a link to the solution?

 

[glueball8]

hmm there's no link, I got there by going to the homepage then press on IPhO 02 and then the questions on the top with the answers on the bottom

I got to the part with 5 equations and 5 unknows but I haven't solved it yet. it seems like just a bit more complex situtation of your problem.