Presentation on theme: "Measuring pressure. Aims Describe the simple mercury barometer and its use in measuring atmospheric pressure Use and describe the use of a manometer."— Presentation transcript:
Aims Describe the simple mercury barometer and its use in measuring atmospheric pressure Use and describe the use of a manometer
The manometer A manometer measures pressure difference.
Atmospheric pressure Gasses are also fluids The atmosphere is made of gasses The atmosphere exerts a pressure Equal to Density changes so must use average
Using atmospheric pressure
Pressure from the air
The mercury barometer Torricelli filled a tube with mercury and inverted it into an open container of mercury. Air pressure Po acting on the mercury in the dish can support a column of mercury 76 cm in height.
Standard atmospheric pressure The pressure that will support a column of mercury of mm heigh is known as standard atmospheric pressure or 1 atmosphere (1 atm). 1 atm = 76 cmHg = x 10 5 Pa = 10 3 millibar (mb)
Pressure from the air As the air is removed from the inside the external pressure crashes the can.
Uses of pressure in fluids
Hydraulic jack The hydraulic press is an important application of Pascal’s Principle.