A mule is a cross between a donkey and a horse. Therefore, a mule will have some donkey characteristics such as large ears, a head just a bit too large for its body, a skimpie â¦ r tail, some still have the cross on their backs from the donkey, and they often have small looking feet.
Density of air. The density of air, Ï (Greek: rho) (air density), is the mass per unit volume of Earth's atmosphere, and is a useful value in aeronautics and other sciences. Air density decreases with increasing altitude, as does air pressure. It also changes with variances in temperature or humidity.
Density is the mass of air molecules per unit volume. Mass is measured by the kilogram (kg), and volume in cubic metres (m 3), so the unit of density is kilograms per cubic metre (kg m -3). We think of kilograms in terms of weight, but weight is the result of a mass subjected to gravity. This says that pressure divided by (density multiplied by a constant) equals temperature. 2  In the demijohn experiment, we increase the air pressure and the density. 3  As it turns out, the % increase in pressure is greater than the % increase in density, so the term p/ r R increases.