Two identical twins, Sallie and Serena, are playing one December on a large merry-go-round (a disk mounted parallel to the ground on a vertical axle through its center) in their school playground in northern Minnesota. Each twin has a mass of 29.7kg . The icy coating on the merry-go-round surface makes it frictionless. The merry-go-round revolves at a constant rate as the twins ride on it. Sallie, sitting a distance 1.77 m from the center of the merry-go-round, must hold on to one of the metal posts attached to the merry-go-round with a horizontal force of 60.0 N to keep from sliding off. Serena is sitting at the edge, a distance of 3.65 m from the center; Serena must also hold on to a metal post on the merry-go-round to keep from sliding off.

a.) What is the ratio of Serena's speed to Sallie's speed (both speeds are measured by a stationary observer watching the spinning merry-go-round)? Hint: the question is asking for Serena's speed divided by Sallie's speed.

b.) With how much horizontal force must Serena hold on to keep from falling off?

c.) If Serena suddenly loses her grip (the size of her gripping force suddenly goes to zero), what will be her horizontal speed when she becomes airborne?