# data[].attributes.body
The ball sinks after being covered because of the built up pressure in the cup forcing it down. the cup is filled with air which has no way to escape when placed on top of the water so it pushed against the water and the ball creating a pressure that forces the ball underwater completely

# data[].attributes.body
The Tin foil ball sinks into the water a bit because buoyant force isn't the only force acting on it, gravity is still acting on the ball causing it to be pulled into the water slightly. This displaces the water so the water level seems higher as the ball displaces it

# data[].attributes.body
As shown, the foil ball flux on the water due to buoyant force (the tendency of lighter objects to stay on top of denser ones).