Pressure Flashcards
What is the equation for pressure (on a surface)?
P = F/A
What is the standard unit for area?
m2
What are the two units for pressure?
N/m2 and Pa
How do you convert from cm2 to m2?
Divide by 10,000 (100 squared)
Can you compress a liquid?
No
Rearrange the pressure equation to have Force on its own.
F = P x A
Rearrange the pressure equation to have Area on its own.
A = F/P
Convert 25N into a mass (on Earth).
2.5kg
How do you calculate the pressure in a liquid?
P = h d g
Pressure (N/m2) = height (m) x density (kg/m3) x G.F.S. (N/kg)
What is the standard unit for volume?
m3
What is the mass of water per m3?
1m3 = 1000kg or 1 tonne
Rearrange the equation for pressure in a liquid so that Height is on its own.
h = p/d/g
What is the equation for energy (work done)?
E = F x d
What happens to air pressure with altitude?
It decreases.
Why can high altitude cause travel illness?
There is not enough oxygen which can make people feel sick.
What is 1 atm?
The mass and therefore weight of air in the column above a 1cm2 area.
What is 1 bar and 1 atm in N/m2?
1 bar = 100,000 Pa
1 atm = 101,000 Pa
What is the equation for volume?
V = A x D (or height)
Why does atmospheric pressure decrease with altitude?
There is less air above pushing down on a certain point.
What is pressure?
The ratio of force spread of an area.
How do you convert mass into a force on earth?
Mass x 10 = Force on earth
What is the equation for density?
Density (kg/m3) = Mass (kg) / Volume (m3)
In a closed system of air: P1 V1 = ?
P1 V1 = P2 V2
e.g. If the volume of the container goes up, the pressure decreases and vice versa
How does a hydraulic system produce an output force?
1) FORCE applied to MASTER
2) FORCE divided by area to create PRESSURE (P=F/A)
3) If system is completely efficient, the non-compressible liquid transfers the PRESSURE to the SLAVE
4) The PRESSURE is multiplied by the second area to create an output FORCE (P x A = F)
What is it important to remember when using area in force equations?
Always convert cm2 to m2 (divide by 10,000)
Although to go from cm2 to m2 you divide by 10,000, what is it important to remember when going from N/cm2 to N/m2?
Multiply by 10,000 instead
What is the equation for work done / energy?
Wd (J or Nm) = Force (N) x Distance (m)
