What appliances use electromagnets

An object moves from the position +34m to the position -15m in 15 seconds. what is it's total displacement? what is it's average velocity?

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.

The electric potential a distance r from a small charge is proportional to what power of the distance from the charge? a. r^-1 b. r c. r^-2 d. r^2