A hollow sphere with a mass of 2 kg and a radius of 15 cm rolls without slipping down a 30° ramp. Starting from rest, how long does it take (in s) for it to travel 14.7 m down the ramp? You may assume that no energy is dissipated due to friction.

At a certain instant after jumping from the airplane a, a skydiver b is in the position shown and has reached a terminal (constant) speed vb = 52 m/s. the airplane has the same constant speed va = 52 m/s, and after a period of level flight is just beginning to follow the circular path shown of radius ρa = 2330 m. (a) determine the velocity and acceleration of the airplane relative to the skydiver. (b) determine the time rate of change of the speed vr of the airplane and the radius of curvature ρr of its path, both as observed by the nonrotating skydiver.