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7. Properties of Matter eLearn.Punjab

Thus, density of the material of the spoon is 8000 kgm-3.

7.7 PRINCIPLE OF FLOATATION

An object sinks if its weight is greater than the upthrust acting on it. An object floats if its weight is
equal or less than the upthrust. When an object floats in a fluid, the upthrust acting on it is equal
to the weight of the object. In case of floating object, the object may be partially immersed. The
upthrust is always equal to the weight of the fluid displaced by the object. This is the principle of
floatation. It states that:

A floating object displaces a fluid having weight equal to the weight of the object.

Archimedes principle is applicable on liquids as well as gases. We find numerous applications of
this principle in our daily life.

EXAMPLE 7.5

An empty meteorological balloon weighs 80 N. It is filled with 103 cubic meters of hydrogen. How
much maximum contents the balloon can lift besides its own weight? The density of hydrogen is
0.09 kgm-3and the density of air is 1.3 kgm-3.

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