FRICTION AND RAMP 1. A 15kg box rest on a horizontal surface (a) What is the minimum horizontal force that is required to cause the box to begin to slid if the coefficient of static friction is 0.35? (b) What is the acceleration of the system if a person pushes the box with a force of 90N if the coefficient of kinetic friction is equal to 0.20? 2. A roller coaster reaches the top of the steepest hill with a speed of it then descends the hill, which is at an average angle of 55 degrees and is 45.0m long. What will its speed be when it reaches the bottom? Assume coefficient of kinetic friction 0.12