1. The problem statement, all variables and given/known data A car with a mass of 560 kg is parked on a hill inclined at 4.5 degrees to the horizontal. a.) What is the force of fricton necessary to hold the car on the slope? b.) If there is ice on the hill and the car is about to slip, what is the coefficient of static friction? 2. Relevant equations Ff = u x Fn = u x mg(costheta) 3. The attempt at a solution The answer I got for part a a = 0 = - (9.8sin4.5 + U9.8cos4.5) u = 0.078 Ff = (0.078)(560)(9.8)(cos4.5) Ff = 427N I'm stuck on Part B Thanks.