Pressure in fluids
This is for students of the higher tier exams
- Created by: Blueglitter08
- Created on: 29-04-20 11:38
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- Pressure in fluids
- Gas pressure and volume
- For a fixed mass of gas at constant temperature:
- Its pressure is increases if its volume is decreased
- reducing the volume of a gas increases the number of molecular impacts per second on the surfaces that are in contact with the gas
- Use the equation pV=constant if the mass and tempertaure of the gas don't change (Boyle's law)
- The tempertaure of a gas can increase if it's compressed rapidly because work is done on it and the energy isn't transferred quickly anough to its surroundings
- =Higher tier
- For a fixed mass of gas at constant temperature:
- Pressure at a surface
- Pressure is the force normal to a surface /area of the surface
- Pressure p=F/A
- The unit of presure is the pascal (Pa), which is equal to 1N/m(squared)
- The force F or area A can be calculated by rearranging the pressure equation
- F=pA
- A=F/p
- Pressure in a fluid
- The pressure in a liquid increases with increasing depth
- A liquid flows until the pressure along the ame horizontal level is constant
- The greater the density of a lquid, the greater the pressure in the liquid
- The pressure p due to the column of height h of liquid of density p is given by the equation p=hpg
- Atmospheric pressure
- Air molecules collide with surfaces and create pressure on them
- Atmospheric pressure decreses with higher altitude because there is less air above a given altitude than there is at a lower altitude
- The density of the atmosphere decreases with increasing altitude
- The force on a flat object due to a pressure difference = the pressure difference x the area of the flat surface
- Upthrust
- The upthrust on an object in a fluid:
- Is an upward force on the object due to the fluid
- Is caused by the pressure of the fluid
- The pressure at a point in a fluid depends on the density of the fluid and the deth of the fluid at the point
- An object sinks if its weight is greater than the upthrust on it when its fully submerced
- An object floats oif its weight is equal to the upthrust
- The upthrust on an object in a fluid:
- Gas pressure and volume
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