The atmospheric air pressure acts in isosteric manner. That is air pressure is exerted in every direction on the object.
How does it help….?
1 - We suck out air in the straw so that air pressure within the straw drops and becomes less than the atmospheric air pressure. The liquid rises in the straw reaches our mouth.
2 - Domestic Vacuum cleaners suck in air and create low pressure area, around the point of suction. The surrounding air is still at the atmospheric air pressure. The atmospheric air pressure pushes in more air to the low pressure area. But the suction continues. This results in an air current formation. The air current carries dust particles along with. The dust particles are trapped in the trash bags and the air is let out.
3 - Siphons work because of air pressure.
4 - The injection syringes utilise atmospheric air pressure. In the first step the piston is drawn in. This creates low pressure within the syringe. The atmospheric air rushes in. The needle is inserted through the cap and the air is pushed in to the bottle. It creates high pressure area in the bottle. The piston is gradually withdrawn it creates low pressure area in the syringe. Medicine in the bottle is at higher pressure so it flows in through the needle into the syringe.
5 - Automobile servicing - uses air pressure to create strong water current to wash away stubborn sticky dust.
6 - Air Brakes - Air pressure is used to activate brakes in trains.
