Tuesday, 14 August 2012

Applications of Atmospheric Pressure

A) Drinking Straw

A drinking straw

1) When air is sucked out from a drinking straw, the air pressure inside become lower.
2) Then the higher atmospheric pressure acting an the surface of the drink pushes the drink into the drinking straw and enables it to be sucked into the mouth.

B) Syringe

A syringe

1) A syringe consists of a tight-fitting piston which moves in a cylinder, with a nozzle at one end.
2) When the nozzle is dipped into a liquid and the piston pulled up, the pressure below is reduced.
3) Then, the higher atmospheric pressure acting on the surface of the liquid pushes the liquid into the cylinder.

C) Siphon


1) The rubber tube is filled with liquid and both ends of the tube are covered with the fingers.
2) When both ends of the tube are opened, liquid flowing out through Y creates a partial vacuum inside the tube.

D) Rubber Sucker

A rubber sucker

1) The rubber cup is made air tight by wetting its rim before pressing it against the wall to create a partial vacuum by driving the air out.
2) Then the higher atmospheric pressure acting in the outer surface of the cup presses it in position against the wall.

E) Vacuum Cleaner

A vacuum cleaner

1) When it is switched on, a fan sucks out a stream of air from the space X to create a partial vacuum.
2) The dust particles are trapped in a dust bag at X while the fast moving air is allowed to flow out from the back of the vacuum cleaner.

F) Lift Pump (Common Pump)

Lift pump

1) During the upstroke V1 closes and the pressure inside the barrel is reduced due to the increase in volume of the air inside it (Boyle's law)
2) The limitation of the lift pump is that it can to raise water up to a height of 10 m only since the atmospheric pressure cannot support a water column of height more than 10 m.

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