184.000 cm/s (4000 mi/hr)
What rate does a molecule at room temperature travel at?
2 x 10 (-10) s
average time between air collisions in the air
4 x 10 (-5) cm
average distance between air collisions in the air
Yes
Does air have weight?
air is compressible
Why doesn't P = dh work with air?
nitrogen, oxygen, water, argon, carbon dioxide
What are the five main constituents of air when it has maximum concentrations of water vapor and carbon dioxide? List them in order
gravity
What causes air pressure?
temperature and quantity of air
What determines the strength of air pressure at sea level
temperature and quantity of air
What does air pressure depend on?
vaccum
total absence of air or any other matter
liter
1000cm(3)
,0127 N
One liter of air weighs...
the weight of the high molecules
What determines air pressure at a given altitude?
temperature
What does atmospheric pressure depend on?
equivalent in all directions
Air pressure is...
14.7 lb/in(2)
atmospheric pressure at sea level
Otto van Guericke (1602-1686)
Who first demonstrated the strength of atmospheric pressure?
no
Does the law of liquid pressures apply to gases?
less than .1kg of air
How much air does the human body displace?
airfoil
any object with surfaces designed to create life in the air
lifting force
net upward force
horror vacui
''Nature abhors a vaccum.'' Taught by Aristotle.
atmospheric pressure is the factor limiting the depth of wells tapped by a water pump
What did Torricelli prove?
liquid barometer
Torricellian device for measuring the pressure of air or any other gas
14.7 lb
How much liquid can an atmospheric pressure of 14.7 lb/in (2) can hold up how much liquid?
standard atmospheric pressure
pressure that will support a mercury column exactly 76cm high when the temperature is 0 C
atmosphere
760 mm Hg, 760 torr, 1.013 x 10(5) pascals, 1.013 bars
mercury barometer
What is the preferred tool for careful scientific work?
1. Awkward 2. Cannot be compared to readings taken at different temperatures 3. Must be in an upright position
What are some of the disadvantages of using a mercury barometer?
manometer
What pressure gauge is a convenient size?
guage pressure
difference between the height of a manometer's columns
absolute pressure
the air pressure of a gas
aneroid barometer
a small, portable barometer that is unaffected by orientation
Blaise Pascal
French Physicist-Philospher (1623-1662)
Boyle's Law
At constant, the volume of a gas is inversely proportional to its pressure
absolute temperature
temperature expressed in kelvins
Charles's Law
At constant pressure, the volume of a gas is directly proportional to its absolute temperature
Avogadro's law
At a given temperature and pressure, two gases of the same volume have the same number of molecules
mole
6.022 x 10 (23)
pneumatic device
a device that transports air or that is driven by air pressure
universal gas constant
R= .0821 L x atm/K x mol
general gas law
PV = nRT
Boyle's law
P(1)V(1) = P(1)V(1)
combined gas law
P(1)V(1)/T(1) = P(2)V(2)/T(2)
a vaccum inside a copper sphere that took 8 horses to pull it apart
What demonstration was staged by Otto von Guericke? What did he prove by this demonstration?
law of liquid pressure and Pascal's principle
What laws pertaining to fluids assume uniform weight density?
In a vaccum
Does something weigh more in air or in a vaccum?
Air pressure is greater under the parachute than over.
How might Bernoulli's principle explain the operation of a parachute?
Aristotle's teaching
What was the horror vacui?
vaccum??
How did Torricelli explain the rise of water in a water pump?
33.9 ft of water, 760 torr of mercury
What height of water is supported by atmospheric pressure? What height of mercury?
He showed that when atmospheric pressure lowered, the column of liquid would fall.
How did Pascal confirm Torricelli's conclusion that mercury is supported at a height of 76 cm by atmospheric pressure?
standard atmospheric pressre
pressure that will support a column of mercury exactly 76 cm or 760 mm, high when the temperature is 0 C
Volume and pressure of a gas are inversely proportional.
State Boyle's law in words.
Volume and temperature of a gas are proportional.
State Charles's law in words.
Kelvin
On what scale must temperature be measured when applying Charles's law?
6.022 x 10 (23)
Define the mole.
P(1)V(1)/T(1) = P(2)V(2)/T(2) P= pressure, V= volume, T= temperature
What is the general gas law? Define each letter.
when a fluid is caught up and entrained by passing air or water
What is entrainment?