A recreational vehicle in the amusement park is traveling on a frictionless track that can make a circular loop as shown in the figure below. The vehicle is released from a point A at a height h from the base of the circular section of the track. (a) What must be the minimum height h required for the vehicle to complete the circular section of the track at point B without falling? If h= 3.50 R and R=20 m, calculate the speed, centripetal acceleration and tangential acceleration of the occupants while the vehicle is at point C (point C is in the horizontal diameter direction).