Apparatus for demonstrating buoyancy of fluids, consisting of a flat-ground glass tube and a plastic disc with rubber covering to form a base plate to which a long string is attached.
The base plate makes a watertight connection with the glass tube and when both are immersed in water, the plate does not sink because buoyancy keeps it pushed up against the tube.
Glass tube: 200 mm x 28 mm dia.
Metal disc: 2 mm x 42 mm dia.
Length of string: 35 cm