I am doing my A level physics coursework on bouncing ball bearings off water. The basic set up is to fire a ball bearing of mass approx 10g and diameter 1cm out of an air gun at approx 20m/s and model its motion as it bounces off the surface of the water. Is it appropriate for me to be considering the coefficient of restitution of the impact of the ball with the water, seeing is water is a liquid not a solid? Or is there some more accurate way of modelling the impact? Any help would be greatly appreciated!