ARCHIMEDES PRINCIPLE:

BUOYANCY AND SPECIFIC GRAVITY

Weigh a metal sample on a triple beam balance (make sure the balance is properly adjusted first) and a clean, dry beaker. Put an overflow can on the rigid support of the balance as in the picture. Fill the can with water. Do not overflow into your already massed beaker. Suspend the mass from the balance arm and catch the overflow in the massed beaker. Take a mass reading of the submerged object. Make sure that no bubbles are adhering to the object. Weigh the beaker with the displaced water.

According to Archimedes' Principle, the buoyant force, Fb = msg - m where

ms = the mass of the sample in air & m = the mass of the sample in water, should equal the weight of the displaced water. Compute the buoyant force and compare it to the weight of the water.

The specific gravity 

Determine the specific gravity of your sample.

Since sp gr  and rw = 1, determine the density of the solid. Compare it with the true density of your material.

Last Updated: 4 Jan 2001
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Comments: Laboratory Supervisor
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