Riders in an amusement park ride shaped like a Viking ship hung from a large pivot are rotated back and forth like a rigid pendulum. At each end of the swing the ship hangs motionless for a moment before the ship swings down under the influence of gravity. Assume that this motionless point occurs when the bar connecting the pivot point and the ship is horizontal. Assuming negligible friction, find the speed of the riders at the bottom of its arc, given the system's center of mass travels in an arc having a radius of 12.8 m and the riders are near the center of mass in m/s. What is the centripetal acceleration at the bottom of the arc in m/s^2? How many times her weight is the normal force exerted by the ride on a 65 kg rider?