To convince you about the awesome force associated with the pressure of the atmosphere on earth we have a demo experiment
in which we allow the force of the atmosphere to
operate unbalanced. The total force
acting on the outside of the
can is approximately
Again a huge force but when the
can is filled with air the same force
acts from within and so has very little effect except for
perhaps a negligible compression if the steel which makes up the
can. However, when we evacuate the can the atmospheric force
is unbalanced and quickly crushes the thin walled can.
It is important to bear this experiment in mind to
safely operate vacuum systems.