1. The problem statement, all variables and given/known data On an icy day, you worry about parking your car in your driveway, which has an incline of 13°. Your neighbor Ralph’s driveway has an incline of 8°, and Bonnie’s driveway across the street has one of 5°. The coefficient of static friction between tire rubber and ice is 0.15. Which driveway(s) will be safe to park in? 2. Relevant equations Force of friction=F*u 3. The attempt at a solution How can we know 'F' without knowning the mass of car?