Passenger cars start at point A with zero initial speed, accelerate as they go down to point B, swing around the circular vertical loop BCB of radius...

Passenger cars start at point A with zero initial speed, accelerate as they go down to point B, swing around the circular vertical loop B→C→B of radius 12m,then go on towards further adventures (not shown). When a car goes through the top of the loop (point C), the passengers feel weightless (for just a moment).What is the height hA of the starting point A above the loop’s bottom B? The acceleration of gravity is 9.8m/s^2.Answer in units of m.