To measure the relative density of solids and liquids by a balanced lever Relative density of a solid A sample of the test solid is attached by a loop of thread to a metre rule pivoted near its mid-point and is balanced by the weight W, of any suitable mass, hung on the opposite side (Fig. 12.8). The […]
Hydrometers If we had performed the experiment with the test-tube and lead shot just described with several liquids of different densities, we should have found that the tube sank to a different level in each of the liquids. In every case, however, the total mass of liquid displaced (equal to volume x density) would have been equal […]
To investigate the law of flotation A measuring cylinder is about half filled with water and the reading noted. An ordinary test-tube with a cotton loop attached is then placed in the measuring cylinder, and lead shot added to the tube a little at a time until the tube floats upright (Fig. 12.6). The new water-level reading in […]
Floating bodies When a piece of wood or other material of density less than that of water is placed in water it sinks until the weight of water displaced is just equal to its own weight. It then floats. Normally, a hydrogen balloon ascends in still air at a steady rate, but it can be made to float if […]
Ships cartesian diver and submarines Bodies which are less dense than water float; those more dense sink. A piece of solid steel sinks, but a ship made of steel floats. Because a ship is hollow and contains air, its average density is less than that of water. An interesting example of a body whose average density can […]
Balloons If a cork is held below the surface of water and then released it rises. The density of cork is less than that of water, so the weight of water displaced is greater than that of the cork itself. In accordance with Archimedes’ principle, the cork is acted upon by a resultant upward force equal to the […]
Relative density of a liquid by using Archimedes’ principle Using the same procedure as in the previous experiment, a sinker is weighed first in air, then in liquid, e.g., white spirit, and finally in water. The sinker is any convenient solid body, e.g., a piece of metal or a glass stopper. Since the same sinker is used in […]
To measure the relative density of a solid by using Archimedes’ principle On page 101 we explained the meaning of the term relative density, and its importance in the accurate measurement of density. By definition, mass of any volume of the substance relative density of a substance = mass f I I f 0 an equa volume 0 water or […]
To investigate Archimedes’ principle for a body in liquid A displacement can is placed on the bench with a beaker under its spout (Fig. 12.2). Water is poured in until it runs from the spout. When the water has ceased dripping the beaker is removed and replaced by another beaker which has been previously dried and weighed. Any suitable […]
Archimedes’ principle Experiments to measure the upthrust of a liquid were first carried out by the Greek scientist Archimedes, who lived in the third century B.C The result of his work was a most important discovery which is now called Archimedes’ principle. In its most general form, this states: When a body is wholly or partially immersed in […]