# Mass Flow Rate

## Definition - What does Mass Flow Rate mean?

Mass Flow Rate is the mass of a substance that is passed through any cross sectional area per unit of time. It can be simply stated as ratio of mass to time. Its unit is Kg per second and it is pronounced as “m-dot.”

Mass Flow Rate = Mass / Time

## Petropedia explains Mass Flow Rate

Mass Flow Rate (a time derivative of mass) is a scalar quantity as it is directly proportional to the mass of an object, which is a scalar quantity as well. Thus, as per Newton’s notation, it can be stated that mass cannot be created or destroyed. The mass of any object is simply its volume that it occupies times the density of this object. For a liquid or gas the object’s density, shape/size and volume can change with the area it passes through in a given time.

Mass Flow Rate can be determined by considering fluid passing through area “A” with velocity “V”, and then its volume "v" will be: v = A x V x t

The mass in this volume is given by: m = r x A x V x t, where r is the density.

Thus, Mass Flow Rate (m-dot) will be: m-dot = m/t = r x A x V