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.
When a gas is moving, it is convenient to use the density of a gas, which is the mass divided by the volume the gas occupies. The sea level standard value of air density r is. r = 1.229 kilograms/cubic meters = .00237 slug/cubic feet. When working with a static or unmoving gas, it is more convenient to use specific volume, which is the volume divided by the mass.