Physics
posted by Brianna .
A matchbox car with mass M rolls down a ramp, starting from rest. It takes a time T to roll a distance L on the ramp. What is the carâ€™s acceleration down the ramp?

assuming linear acceleration.
avg velocity=L/T
but avg velocity= 1/2 Vf
Vf=2L/T
but Vf=at
2L/T=aT
solve for a 
Thank you for your help!