# Rolling car down a hill

1. Nov 30, 2008

### fk378

1. The problem statement, all variables and given/known data
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?

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

3. The attempt at a solution
I don't know how to start this....how do you find the acceleration?

2. Nov 30, 2008

### glueball8

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

Last edited by a moderator: May 3, 2017
3. Nov 30, 2008

### 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?

4. Nov 30, 2008

### 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.