Theory:
Free falling accelerate in the air, any gases, water or any liquids is:
a= K* (m1-m2)/m1
Proof
When two object touch each other, perform themselves a force relevant with their masses.
F1= k*m1
F2= k*m2
Net force on m1 mass is:
Fnet = F1-F2
accelerate is dividing force to the mass. So that;
accelerate: a = (F1-F2)/m1
= (k*m1-k*m2)/m1
>> a=k*(m1-m2)/m1
Proven.
In this formula, k is calculated as 9,811 by many examples.
Examples
Any objects falls in the air:
Iron free falls in the air: a= 9,811*(7850-1,225)/7850= 9,81 m/s^2
Water/or human free falls in the air: a= 9,811*(1000-1,225)/1000= 9,799m/s^2
Any object equal to mass of air: a=9,811*(1,225-1,225)/1,225=0 (stops in the air)
An helium ballon (the weight of plastic material is neglected) a= 9,811*(0,169-1,225)/0,169= -61,30m/s^2 (to upward)
Helium actually has the potential to move up much faster. but this speed will decrease as the balloon plastic material aggravates the balloon.
Any objects falls in the water:
Iron free falls in the water: a=9,811*(7850-1000)/7850= 8,56 m/s^2
Human free falls in the water: a= 9,811*(990-1000)/990= - 0.10 m/s^2
-0,10 means 10 decimeter upward per a second. This is not so much. So that, a person's swimming or sinking in water is proportional to the body mass index; water ripple or water stream.
Wood free falls in the water: a=9,811*(550-1000)/550= -8,03m/s^2 (a wood never shrinks in the water)
The steps of theory, proof and examples is completed.