What is an object’s acceleration due to gravity on earth?

The acceleration of gravity on or near the surface of the earth is right around

( 9.81 m/s² )

It varies slightly at different places on Earth.  But it doesn't depend on an object's mass ... EVERYTHING falls with the same acceleration, because that's the way gravity works.  

If you see an object dropped and it DOESN't accelerate at that rate on the way down, that was only because of air resistance.  

(Many museums have exhibits where they have a sealed chamber made of glass, that you can see into but they pump all the air out of it.  Then a machine inside drops a feather and a rock at the same time, and they fall together and hit the bottom at the same time.)

this is poiselle's equation from fluid mechanic in physics. mech eng

wavelength divides in half and speed stays the same.