1. The problem statement, all variables and given/known data Acceleration of a car is -12.2 m/s/s. The car has a mass of 925 kg. Find the frictional force. 3. The attempt at a solution So A=-12.2, M=925 kg Fnet=MA =925(-12.2) = -11285 N Fg=mg =925(9.8) =9065 N Since there is no vertical direction, Fg=Fnorm. Now I have the equation Ff(frictional force= coefficient(normal force) I'm really stuck here. I need to know the Fa or the coefficient to solve?