8. A roller-coaster car is released from rest at the top of the first rise and then moves freely with negligible friction. The roller coaster shown in the Figure below has a circular loop of radius R=10 m in a vertical plane. The mass of car and riders is 400 Kg (a) Suppose first that the car barely makes it around the loop. Find the required height of the release point h above the bottom of the loop. (b) If the release point is at or above the minimum required height what is the normal force on the car at the bottom and at the top of the loop?