Alternating current is normally produced by a

Alternating Current (AC) is the electric current in which the magnitude and direction vary cyclically.

In other words:

It is a variable electric current in which electrical charges change the direction of movement periodically.

Unlike Direct Current (DC), that is produced by a chemical reaction (a battery, for example), alternating current is produced by a generator that converts mechanical energy into electrical energy.

answer; how far out of place which the object finished relative to the starting location;

a skateboard rolling across the street - apex