A roller-coaster car has a mass of 506 kg when fully loaded with passengers. The path of the coaster from its initial point shown in the figure to point B involves only up-and-down motion (as seen by the riders), with no motion to the left or right. Assume the roller-coaster tracks at points and are parts of vertical circles of radius r1 = 10.0 m and r2 = 15.0 m, respectively.
(a) If the vehicle has a speed of 20.5 m/s at point , what is the force exerted by the track on the car at this point?
____N
(b) What is the maximum speed the vehicle can have at and still remain on the track?
_____ m/s