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.
1 At sea level and at 15Â°C, the density of air is 1.275 kg/m 3. 2  This is the value of the ISA or International Standard Atmosphere. 3  At 20 Â°C and 101.325 kPa, the density of dry air is 1.2041 kg/m 3.