(L13) S&F L3 - Liquids and Gases Flashcards
What is Pascal’s principle?
pressure applied to an enclosed fluid is transmitted undiminished to every part of that fluid as well as the walls of the container.
What is atmospheric pressure?
Atmospheric pressure is pressure at a given point in the earth’s atmosphere.
depends of geographical location, altitude, and time. (pressure at sea level is 1*10^5 Pa.)
For fluid at constant density, what is equation for difference in pressure between fluid height of y1 and y2?
ρ = density (in kg m-3)
g = acceleration due to gravity
(in kg m s-2)
P1 = pressure at point 1 (in Pa)
P2 = pressure at point 2 (in Pa)
what does difference in pressure between fluid height of y1 and y2 tell us about the weight of molecules?
weight of all molecules adding up to pressure difference.
Where is the reference of height y1 and y2 of fluid?
equal or below the lowest point of fluid.
If point 1 is at depth H, and point 2 is at surface, what is P of point 2?
Atmospheric pressure
What can this equation be rearranged for?
P.surface = pgh
p,surf = P,atm
P,atm = pgh
Atmospheric pressure = density * gravity * height
What is absolute pressure?
Pressure measured relative to a vaccuum of 0Pa
What is gauge pressure?
Pressure measured relative to atmospheric pressure of 1*10^5Pa
What is absolute pressure equation?
P= P,atm+P,g
What is gauge pressure equation
Pg = P- P,atm
What is a manometer?
Measures gauge pressure.
What is gauge pressure equal to in a U-Tube experiment?
Gauge pressure is equal to difference of ‘weight’ in the 2 columns.
What is pressure like in equal depth of stationary fluid of uniform density?
Pressure is the same at equal depth in a stationary fluid of uniform density
What do the 2 purple points in this image tell us?
Pressure is the same at equal depth in a stationary fluid of uniform density
What is the equation for
p = density
g = accel due to gravity
yA/yB = height of each column
guage pressure = difference of weight between the 2 columns
What is a mercury barometer for?
Measures atmospheric pressure.
p, density, is the density of mercury
What is a bourdan gauge?
Flexible tube enclosed at one end.
At other end pressure is applied.
Increase in pressure straightens tube and moves pointer of measurement across a scale.
What are electronic transducers?
Frequently used to measure gauge pressure.
Pressure acts on its face, causing it to bend. The strain on its face changes the resistance of wires underneath its face.
Which acts as a pointer for a scale of measurement.
What is equation for pressure at each level?
