Flashcards in Pressure And Density Deck (11):
What is density measured in?
How to work out pressure
Pressure = force/area
What is pressure measured in?
• N/m² = Pa (pascal)
What three factors affect the pressure in a fluid?
• Depth the pressure is measured at (the greater the depth, the greater the pressure)
• Density of the fluid (the greater the density, the greater the pressure)
• Gravitational field strength (the greater the gravitational field strength, the greater the pressure)
What equation links all the three factors affecting pressure?
• pressure = depth x density of fluid x strength of gravity
• p(Pa=N/m²) = h(m) x p(kg/m³) x g(10N/kg)
Three holed can
• This can shoes that pressure in a fluid increases with depth.
• Top hole comes out slowest and travels the least distance across, but the bottom hole moves out fastest and travels furthest.
• Two metal cups that fit together. If most of the air is removed from inside them using a vacuum pump, it's nearly impossible to pull them apart.
• The pressure of the atmosphere acting on their outside surfaces pushes them tightly together - there is no pressure on the inside because there is no air.
• Once air is let back in, the pressure inside equals the pressure outside and the cups can be easily separated.
• Water is boiled in an empty drinks can.
• When the water has boiled, steam fills the can.
• If the can is then turned upside down in a trough of cold water, the steam condenses and the air pressure inside goes down - causing the can to collapse due to the pressure of the air outside.
How to work out density
Density = mass/volume
Why does air pressure decrease the higher up you go?
• Atmospheric density increases the higher up you go.
• Air is colder higher up, so the molecules are moving less slowly.