A man is fishing in a stream. He is watching a fish in the water until the fish swims away and suddenly the fisherman can no longer see the fish. What is the minimum angle that light from the fish makes with the normal of the water surface such that the light is not transmitted out of the water

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.