Will an orange float or sink in water? Find out with this quick experiment!
Equipment: glass container, water, two oranges.
Toss the unpeeled orange in some water. Note that it floats. Put the peeled orange in the water – it sinks!
Orange peels are porous and filled with air pockets. One can compare the peel to a life jacket; it makes the orange’s average density less than that of water, which allows the orange to float on the water's surface. But removing the peel from the orange will cause it to sink immediately since the density of the orange without its air-riddled peel is greater than the density of the water.
The force pushing the oranges to the surface of the water is known as the buoyant force and can be calculated using Archimedes’ principle. If the buoyant force on a certain object exceeds the force of gravity, the object with float on the surface of the water. The buoyant force is proportional to the volume of the object, and thus the object’s average density can indicate whether or not the object will float. If the object’s average density is greater than that of the water its volume will displace, it will sink.
Safety precautions: none.

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