Pressure In Liquids And Gases Flashcards
What is a fluid?
Substance that can flow –> either a liquid or a gas
What is pressure in depth?
The pressure in a liquid increases with depth because the pressure at any point in a liquid is due to the weight of the liquid above that point
The weight of liquid depends on density
What is pressure in a fluid?
When the particles of a fluid collide with the surface such as a container they exert a force at a right angle to the surface
Pressure is the force acting per square metre
Measured in Pa or N/m^2
How do you calculate pressure in a column of water?
Height x density x gravitational field strength
To calculate difference in pressure, work out pressure at different heights and calculate difference
What is upthrust?
An object that is partially or completely submerged in a fluid experiences a great pressure on its bottom surface than its top surface
The difference in pressure creates an upwards resultant force on the submerged object
When will an object sink?
When weight is greater than upthrust
The upthrust is equal to the weight of the fluid it displaces
An object that is more dense than the fluid will sink because it’s weight is greater than the weight of the fluid displaced
What is atmospheric pressure?
Air molecules collide with surfaces
This decreases with altitude as there are fewer air molecules in total above the surface so weight above the surface decreases
Density decreases so there are fewer air molecules per m^3
