Liquid Density

We compare the density of oil, salt water and fresh water using displacement tanks. Equally weighted measuring cylinders are placed into the three liquids and the amount of water displaced is collected for comparison. Physics - Forces - Learning Points. A displacement tank can be used to measure the volume of an irregular object. The density of a liquid affects buoyancy. A floating object displaces its own mass of liquid. The Plimsoll line is designed to prevent the dangerous overloading of ships. A Twig Experiment Film. Let students experience real experiments in lab conditions anywhere, from setup, method all the way through to analysis and real-world application.