The weight of 20 kg is
(mass) x (gravity) =
(20 x 9.8) = 196 newtons, downward.
There must be a force of 196 newtons upward on the mass.
Otherwise the mass is accelerating either up or down.
Oxygen... Hope this Warner helps
A natural system is formed when components are grouped together so as to perform a more specific function or use. In addition, this system is bound to exist without any human interference. Biological and non-biological components work hand-in-hand as they do nature processes.