Question

A balloon is filled with air and sealed. The direction of the pressure on the baloon wall from the air inside the balloon is?

Answer 1

If you fill a balloon by some air and seal it, then in room temperature(~300K) the air molecules have thermal energy released as kinetic energy of the molecules, and so the molecules are continiously colliding with the inner surface of the balloon, and pressure is the force perpendicularly exerted on unit surface area. So at some point of the surface, pressure due to the inside air, is perpendicularly outward to the surface at that point. Hence the aggregate result is perpendicularly outward to the balloon surface at every point on the surface.