Question

what will happen if density of ball bearing is less than density of glycerine oil

Answer 1

Hey mate :) your answer is
here

Absolutely nothing. The oil is the the shed, the ball bearing is in that little tub for random objects next to the back door. As they are nowhere near each other, nothing is happening.
Of course, lots of things are happening all the time, but it’s nothing to do with either the oil or the ball bearing. Probably.

Hope of help