Oscillation or vibration.
TO AND FRO MOTIONIt is the motion in which a body moves in fro and to directions.EXAMPLEMotion of simple pendulum
because it moves in a slow motion and it projects images
If there is no force acting against the motion, then no force is required to maintain the motion.
kinematics
It is called, breeze, wind, gale, zephyr, etc.