How can I calculate thrust in Newton from mass flowrate and velocity?

Please note,I have mathematical skills of 7 year old,the most complex task I can do is multiply and divide,I dont understand any equations.

  • $\begingroup$ :') Thank you for your candour. Start here. You can do it! $\endgroup$
    – Petrichor
    Feb 8, 2018 at 16:20
  • $\begingroup$ I visited that site two times before I asked this question,I cant do it.I want to calculate thrust of fan,it moves 5 cubic meters of air per second with airflow velocity of 5 meters per second. $\endgroup$ Feb 8, 2018 at 16:34

1 Answer 1


Well the best learning happens when there is a need, and the internet can answer almost any question. Easiest way to understand physics is to use SI derived units and always carry your units through your equation.

velocity = 5 m/s
mass flowrate = ?kg/s
volumetric flowrate = 5m^3/s
Thrust: ? Newtons = kg*m/s^2

I asked google what the mass of a cubic meter of air was:
density = 1.293 kg/m^3

The density lets us convert your volumetric flow into mass flow:
(looks like googles calculator carries units now which is cool)

5m^3/s * 1.293 kg/m^3 = 6.465 kg/s
mass flow = 6.465 kg/s

Now we just multiply mass flow and velocity and confirm our units work out:
6.465 kg/s * 5 m/s = 32.325N

So the thrust is 32.325N or 7.27 pounds force


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