Q5) (20 points) A roller coaster starts from rest at the top of an 25-m hill as shown. The car travels to the bottom of the hill and continues up the next hill that is 15 m high. (ignore friction). 25 m B 20m C a- Calculate the speed of the car at the lowest point (point A) 15 m b- If section BC is rough such that the car stopped at point C (20 m to the right of point B), calculate the coefficient of Kinetic friction between the car and section BC.