points 1 and 2 lie on a streamline, the fluid has constant density, the flow is steady, and there is no friction. Although these restrictions sound severe, the Bernoulli equation is very useful, ...

The same mass takes up a bigger volume - this means the gas is less dense. Density also depends on the material. A piece of iron with the same dimensions as a piece of aluminium will be heavier ...

Population density (often abbreviated PD) is a compound measure that tells us roughly how many people live in an area of known size. It is commonly used to compare how 'built-up' two areas are.

Density is usually calculated using a mathematical function of temperature, salinity, and pressure, sometimes called an equation of state. For many years the internationally accepted standard for ...