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The PhET simulation on is an excellent introduction to the concept. This is similar to the PhET  simulation encountered in Section 10.1 but the underlying issues are more subtle and significant here.

First click on the Intro tab. Here you will find two blocks, one of which floats and the other sinks in the chosen liquid (oil or water) in the tank. Also, in this simulation, there is a second weighing scales immersed inthe liquid in the tank which can be used to determine the net downward force on a block when immersed in the liquid. Subtracting this value from the correponding force (the weight) measured using the weighing scales in air, one obtains a value for the buoyancy force (the upthrust) on the body.

Archimedes' principle requires that this buoyancy force be equal in magnitude to the weight of fluid displaced by the body. The simulation displays the volume of liquid displaced, so you should record this value when the body is totally immersed (if a body tends to float, you can hold it beneath the liquid surface using the mouse). To determine the weight of fluid displaced you simply multiply the volume of fluid displaced by the density of the fluid (1000 kg m^–3 for water, 920 kg m^–3 for oil) and the acceleration due to gravity.

The Buoyancy Playground option (click the relevant tab in the PhET  simulation) may be used to confirm Archimedes' principle for a range of different liquids.

The Youtube video on from describes some nice applications of buoyancy forces and of Archimedes' principle.