Pressure , Pascal`s Law , Hydraulic Press

Pressure Page in my Physics-World Software

PRESSURE:
Pressure is the force acting on a certain area.Your feet sink into loose sand when you stand on it.If you lie on sand you do not go down very far. In each case The force acting on the sand is the same weight of you body .when the force acts on an area the size of your whole body.The pressure is lower

HIGH AND LOW PRESSURE:

A sharp knife cuts better than a blunt one.This is because there is much less area on the cutting edge if the blade is sharp.So the pressure is higher.

A liquid presses on every side of anything that is put in it. The pressure is caused by the weight of liquid .Pressure increases with depth.So the pressure at the bottom of the ocean is much greater than near the surface. Deep sea drivers have to wear special suits to prevent their bodies being crushed.

Altimeter- relationship of altitude to atmospheric pressure

 

The earth is surrounded by layer of air , called the atmosphere.We live at the bottom of this layer.The air above presses down on us with a force of one kg on every sq cm (14.7 Ibs on every sq inch). This is called the atmospheric pressure.If you hold out your hand , there is force of nearly 10 kg (22 Ibs) pressing down on it .You can`t feel it.because an equal force is pressing up on the other side of your hand,and the two balance out.

A Bicycle pump

 

Nature tries to make pressure equal everywhere.A bicycle pump compresses the air inside it. This makes the pressure of the air inside the pump greater than the pressure of the air in the Tyre.So air moves into the Tyre.

A bicycle pump works by increasing the pressure .

You suck up liquids through a drinking straw

You suck up liquids through a drinking straw you take out of the straw. To make the pressure the same as it were before.The atmosphere pushes liquid from the glass up the straw into your mouth .You keep drinking by continuing to suck .This keeps the pressure in your mouth lower than atmospheric pressure . A vacuum cleaner works on the same principle. A fan makes the pressure in the cleaner lower than the pressure outside .So air rushes in falling with it the dirt on the floor.

Altimeter- relationship of altitude to atmospheric pressure

As you climb above sea level the pressure of the atmosphere decreases .This is because at great height there are fewer air molecules around . People who climb very high mountains such as Everest have to take their air supply with them . There is not enough air for them, and so they breathe from oxygen cylinders.The cabins of aircraft which fly very high also have to take their air supply with them .If they did not ,then the cabin would not stay at atmospheric pressure.The cabin is said to be pressurized.

BAROMETERS:

Torricelli invented mercury barometer in the year 1643

Mercury Barometer

Aneroid Barometer

                                                                       3D animation showing working of Aneroid Barometer.


Barometers measure atmospheric pressure and are used for weather forecast. A Mercury barometer is very simple. It measure how much mercury the atmosphere can hold up. As the pressure changes the height of the mercury changes .


An Aneroid barometer is more complicated .It is a sealed metal box with thin walls There is no air inside it and the sides are held apart by a spring.As the pressure outside increases or decreases the side of the box go closer together or further apart .The movement of the top of the box moves levers which a pointer over a scale.

Height of water indicates pressure in different pipes which are connected with main water Tank

The can full of water has small holes pierced in it the jet of the water from the bottom hole is strongest and shoots out water straightest .This is because the pressure of a liquid increases with depth. The water at the bottom is under the greatest pressure. 

 

                                                                         3D Animation Showing Water Pressure in different  heights of the holes in water Can
                                                                        


The can full of water has small holes pierced in it the jet of the water from the bottom hole is strongest and shoots out water straightest .This is because the pressure of a liquid increases with depth. The water at the bottom is under the greatest pressure. 

Pressure Cooker

                                                                        3D animation showing Pressure Cooker Utility



Pressure Cooker:

Pressure Cooker is a type of cooker which is use for cook or boil any food grain , vegetables,fruits,animal flesh more faster.  Pressure cooker increases foods and water boiling point more higher, by applying more air pressure on it by air-tight lid.This process help to boil and cook foods more faster.When the air pressure increases extremely within a pressure cooker then the excess pressure release from cooker through the side safety valve. 

Pascal`s Law Page in my Physics-World Software

PASCAL`S LAW:

French scientist and philosopher Blaise Pascal (year 1623 - 1662)

If we change the pressure of a point  of  fluid in an enclosed place then same amount of pressure change occur all the points of the fluid. This incident first observed by the French scientist and philosopher Blaise Pascal (year 1623 - 1662) . He first construct this observation into formula known as Pascal`s law of pressure distribution of fluid.

Pascal`s Vases

Pascal`s Law

LAW:
Pressure given into any part of the fluid in an enclosed place is distributed in unchanged form everywhere and acted vertically on the adjacent surface of a fluid.If we give pressure on the plane of the Water filled porous (with many small holes) rubber ball,  the water is spilled out vertically from every pore in a same speed.

Hydraulic Press

HYDRAULIC PRESS:

It made of two  container of same length but one with narrow and one with broad mouth . Both  container are attached with a narrow  pipe and fill with fluid , narrow connecting  pipe have a valve which restrict the flow of fluid in a one way. Both container have piston . There is a fixed platform over the container with broad mouth. Place a object for press in between piston of the broad mouth and fixed platform. Use or press small force on the narrow mouth container, this force is then distributed through fluid and one way valve to the piston of the wide mouth container and press the object with the fixed platform with many time higher force. 

                                                                     3D Animation showing Working of Hydraulic Press