Dry friction: Produces a force normal to the surfaces of contact. Occurs only when two objects are moving past each other. Occurs when objects are in a condition of sliding or a tendency to slide. Occurs only when two objects are in a condition of a tendency to slide.

In science and physics what is the standard unit of measure for speed?

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.

This is the number of complete movements of a wave per second.