A roller-coaster car has a mass of 500kg when fully loaded by passengers. The car passes over a hill of radius 15 m. At the top of the hill, the car has a speed of 8.0 m/s. what is the force of the track on the car at the hill? If the car has the similar mass which is 500kg, but at the bottom of a circular dip of radius 40 m and the car has a speed of 16 m/s. what is the magnitude of the force of the track on the car at the bottom of the dip?