A motorcycle skids to a stop on a road. What is the equal and opposite force for the force of the motorcycle's friction pushing on the road as
described by Newton's third law?
Choose 1
Normal force of the road pushing up on the motorcycle
B
Earth's force of gravity pulling down on the motorcycle
Friction of the road on the motorcycle in the opposite direction
D
Motorcycle's force of gravity pulling up on the Earth

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.