Question

what is random motion

Answer 1

Motion in which direction keeps on changing is called random motion .
eg. butterfy flitting from flower to flower.

Or,
Random Motion is a motion in which an object didn't go in a straight manner, the object move in a zig zag manner. This is called Random Motion.

EXAMPLES OF RANDOM MOTION
fish swimming in water
motion of bird
motion of butterflies
motion of ants
motion of dust particles.