This text and the experiments were created by sciences teacher of Genisea junior High School of Xanthi, Greece, Mrs. Lakka Irini.
The first experiment that takes place demonstrates the principle of the buoyant force.
The students realize that the buoyant force exists whether the object floats or sinks.
They are able to measure it and see that opposes the weight of an immersed object.
They calculate it thought the apparent weight and they realize that it gets bigger as the volume of the sinking object gets bigger.
The second experiment helps them to measure the buoyant force and see that it is equal to the weight of the fluid displaced by the object. They measure the volume of the sinking object and the weight of the displaced fluid in order to realize that they are equal.
The third experiment demonstrates the fact that objects of different density and equal volume have equal buoyant force. They measure the volume of the three objects and the assume that since the objects display the same quantity of fluid must have the same force.