Matter and Measurement

Date: 2015-10-07; view: 477.

READING PASSAGE

Unit Three MATTER AND MEASUREMENT

Matter, in science, is the general term applied to anything that has the property of occupying space and the attributes of gravity and inertia. In classical physics, matter and energy were considered two separate concepts that lay at the root of all physical phenomena. Modern physicists, however, have shown that it is possible to transform matter into energy and energy into matter and have thus broken down the classical distinction between the two concepts. When dealing with a large number of phenomena, however, such as motion, the behavior of liquids and gases, and heat, scientists find it simpler and more convenient to continue treating matter and energy as separate entities. Certain elementary particles of matter combine to form atoms; in turn, atoms combine to form molecules. The properties of individual molecules and their distribution and arrangement give to matter in all its forms various qualities such as mass, hardness, viscosity, fluidity, color, taste, electrical resistivity, and heat conductivity, among others. In philosophy, matter has been generally regarded as the raw material of the physical world, although certain philosophers of the school of idealism, such as the Irish philosopher George Berkeley, denied that matter exists independent of the mind. Matter exists in three states: solid, liquid and gas. A solid, for example a stone, has a definite shape and a definite volume; a liquid, for example oil, has definite volume but no definite shape; a gas, for example hydrogen (H), has neither definite shape nor volume. Water can exist in all three states; below 0o C as a solid (ice); between 0oC and 100oC as a liquid (water); and above 100oC as a gas (vapor). All matter consists of elements such as zinc (Zn) or oxygen (O), or of compounds such as nitric acid (HNO₃) or sulphur dioxide (SO₂).

When we measure quantities of matter, we may use the fundamental units of time (e.g. the second), mass (e.g. the kilogram) and length (e.g. the meter). Or we may use the units such as area (e.g. m²) or volume (e.g. cm³) or density (e.g. g/cm³). These are known as derived units. The area of a rectangle is found by multiplying the length by the width. The density of a substance is equal to the mass divided by the volume (d = m/v). We use the terms specific density or relative density to indicate density relative to the density of water. Mercury (Hg) has a density of 13.6g/cm3. This means that a cubic centimeter of mercury has 13.6 times the mass of a cubic centimeter of water.

(Adapted from different sources)