1. A boy sitting on a seat of a Ferris wheel moves in a vertical circle at a constant speed. What is the magnitude of the centripetal force of the boy at the bottom of the circle? FN is the magnitude of the normal force that the seat exerts on the rider and m is the mass of the rider. a) FN b) mg c) FN- mg d) mg FN e) FN+mg f) zero because rider is at the top. 2. Two small objects, with masses m and M, are originally a distance r apart, and the magnitude of the gravitational force on each one is F. The masses are changed to 2m and 2M, and the distance is changed to 4r. What is the magnitude of the new gravitational force? a) F/16 b ) F/4 c) 16F d) 4F e) F/2 f) F 3. A tetherball m is attached to a light string of length _ - 120 cm as shown in the figure. This tetherball moves in a horizontal circle with a constant speed. If the angle 0 is measured to be 180, what is the speed of the mass? a) 0.55 m/s b) 2.0 m/s c) 3.8 m/s d) 1.3 m/s e) 1.1 m/s