Physics Review Flashcards
3 physical states of a substance
solid, liquid, gas
Solid
- Atoms/molecules are closely approximated due to lattice.
- Have volume and shape
- Motion is limited, only vibrate in position
Liquid
- Molecules exert weaker force on each other called Van der waal forces
- allows fluid flow, sliding, and the molecules can move throughout the substance.
- Takes shape of container, has volume.
- Have more kinetic energy
Gas
- Molecules are independent of each other
- Molecules are constantly moving
- No definite shape or volume
- Measured by flowmeters or respirometers
Inverse Relationship
The value of one parameter decreases as the value of the other parameter increases
Direct Relationship
Where two variables do the same thing
Saturated Vapor Pressure
Pressure exerted by a vapor when, at any one temp, an equilibrium is reached at which the same number of molecules are vaporizing as are returning to liquid
Boiling Point
The temp at which vapor pressure becomes equal to atmospheric pressure and at which all liquid changes to gas
Vapor pressure and boiling points are ___ related
inversely related
Force
That which changes or tends to change the state of rest or motion of an object
__=mass x acceleration (Newton’s 2nd law)
Pressure
- Force applied over a surface
- Pa = pascal
- kPa is usual unit utilized
Absolute Pressure
gauge pressure + atmospheric pressure
Boyles Law
- At a constant temperature, the volume of a given gas varies inversely with the absolute pressure.
- P1 x V1 = P2 x V2
Charles Law
at a constant pressure the volume of a given gas varies directly with the absolute temperature
-V1/T1 = V2/T2
Gay Lussac’s Law
at a constant volume the absolute pressure of a given mass of gas varies directly with the absolute temperature
- P1/T1 = P2/T2
Dalton’s Law of Partial Pressures
In a mixture of gases, the pressure exerted by each gas is the same as that it would exert if it was alone in the container.
Avogadro’s Hypothesis
equal volumes of gases at the same temperature and pressure contain equal numbers of molecules (a mole)
1 mole = 6.022x10^23
Universal gas constant
Constants: PV, V/T, P/T
PV/T = universal gas constant
universal gas law (ideal gas law)
PV=nRT
Critical Temperature
the temp above which no amount of pressure can liquefy a gas
Critical pressure
the pressure to liquefy a gas at its critical temperature
Solubility
solution is a homogenous mixture of a solute (gas) in a solvent (liquid)
depends on: partial pressure of gas, temperature, gas, liquid
Henry’s law
at a certain temp, the amount of a given gas dissolved in a given liquid is directly proportional to the partial pressure of the gas in equilibrium with the liquid
La Chatelier’s Principle
a change in any of the factors in determining an equilibrium causes the system to adjust or reduce or counteract the effect of the change.
solubility coefficient
the volume of gas which dissolves in one unit volume of the liquid at the temp concerned
partition coefficient
the ratio of the amount of substance preset in one phase compared with another (the two phases being of equal volume and in equilibrium)
Blood gas partition coefficient
reflects the proportion of the anesthetic that will be absorbed in the blood verses the amount of anesthetic that will leave the blood to diffuse into tissues
oil gas partition coefficient
ratio of a gas present in oil verses in the gas state.
Indicates how efficiently a gas can access and affect the sites of action.
diffusion
the continual movement of molecules among each other in liquids or in gases. Occurs from areas of high concentration to areas of low concentration.
What are things that make a difference to rate of diffusion?
- thickness of membrane (d)
- size of a molecule (MW)
- surface area of the membrane (A)
- solubility of the gas (S)
- pressure gradient (P1-P2 or change in P)
Fick’s Law
the rate of diffusion of a substance across unit area is proportional to the concentration gradient
Graham’s law
the rate of diffusion of a gas is inversely proportional to the square root of its molecular weight
cohesion
internal attractive forces between like molecules trying to stick together in the smallest shape possible.
adhesion
attractive forces between unlike molecules trying to stick to something different
surface tension
cohesive forces at the surface of a liquid that tend to keep liquid in the most compact form.
-heating lowers ___
P=hdw
pressure in liquids
Density of H2O = 1gm/cc
Density of Hg = 13.6 gm/cc
convert cm h20 to mmHg: 0.74 x __
convert mmHg to h20: 1.36 x ___
flow
the quantity of fluid passing a point in a given time.
F=Q/T
laminar flow
fluid movement in smooth layers with no turbulence or eddies.
flow is greatest in center, becomes slower as it gets closer to a wall.
turbulent flow
flow is not smooth but has swirls and eddies
what changes resistance to flow
- diameter of channel
- length of channel
- nature of the flow (laminar vs turbulent)
- viscosity of fluid
viscosity
frictional forces between layers within a fluid
hagen-poiseuille equation derivative
Resistance = 8nL/πr4
-radius matters the most
Poiseuille’s law
P1 – P2 = Resistance x Flow
looks at flow rate in relation to resistance and the pressure gradient if you have an ideal fluid and no turbulence
Bernoulli Effect
Given a channel with a narrowing which then
increases, the pressure measured along the
channel is lowest at the narrowest point, often
below atmospheric
Narrowing causes increased velocity, thus
increased kinetic energy. To maintain unchanged
sum of energy, the potential energy must decrease.
Laplace’s Law
Relationship of wall tension, pressure, and radius of
cylinders (vessels) and spheres (ventricles and alveoli*)
Heat
kinetic energy of molecules of substance
Calorie (cal)
energy to increase temp of one gram of H2O 1 degrees celcius
1kcal=C=4184 joules=energy to increase temp of 1kg H2O 1 degrees celcius
Temperature
the parameter used to describe the amount of heat possessed
F to C
Tc = 5/9 (Tf – 32)
C to F
Tf = 9/5 Tc + 32
C to K
Tk = T c + 273
Kelvin and triple point
- necessary for calculations in gas laws
- all atomic motion ceases at 0 kelvin
- the temperature at which water, ice, and water vapor are all in equilibrium
First law of thermodynamics
heat is a form of energy and can be converted to other forms of energy, but neither created nor destroyed
second law of thermodynamics
heat always flows from warmer to cooler (think high to low). There must exist a difference in temp and the two things must be in contact.
Methods of heat transfer
conduction
radiation
convection
evaporation
conduction
heat movement through a substance by the transfer of kinetic energy from molecule to molecule.
2% heat loss
Radiation
heat transferred from warmer to cooler objects by emission and absorption of energy radiated in varying wavelengths
objects do not have to be touching
40% heat loss
convection
heat transfer occurs by moving fluid (liquid or gas)
air adjacent to body is warmed, it expands and moves away, and it carries the heat away
evaporation
the loss of latent heat of vaporization of moisture on the skin’s surface
latent heat of evaporation - the heat required to change liquid into vapor
specific heat capacity
the amount of heat required to raise the temp of 1 kg of a substance by 1 kelvin
- Water is standard: 1 cal/g/C = 1 kcal/kg/ C
- 1 cal=4.18 joules
heat capactity
the amount of heat required to raise the temp of an object by 1 kelvin
-calculated by multiplying the mass of the object with the specific heat capacity
specific latent heat
energy required to convert 1 kg of a substance from one phase to another at a given temp (J/kg)
latent heat of fusion
the heat required to change a solid to a liquid
latent heat of vaporization
heat required to change a substance from a liquid to a gas at a constant temp
latent heat of vaporization
heat required to change a substance from a liquid to a gas at a constant temp
Joule-thompson effect
(joule is cool)
when nitrous cylinder is allowed to empty rapidly, the cylinder becomes very cold and the water vapor from the surrounding air freezes on the cylinder
radiation (xray vs LASER) atomic structure
protons (+)
neutrons (neutral)
electrons (-)
Types of electromagnetic radiation: Ionizing
- releases energy by removing electrons from atoms in tissue creating atoms that are very hazardous
- xrays, gamma rays, radiation tx for cancer, dangerous if absorbed
Nonionizing electromagnetic radiation
- discharges its energy without creating ions or removing electrons from atoms in tissues
- infrared radiation, visible light, UV radiation, LASER
protection from ionizing radiation
-DISTANCE is best form. At least 3 feet away.
-minimize TIME
-use barriers to SHEILD (lead aprons)
6 ft of air is the equivalent to 9 in of concrete or 2.5 mm lead
Maximum yearly occupational exposure of ionized radiation
- no more than 5 rem or 5000mrem
- one CXR is 25 mrem
- flouroscopy procedure could produce >8000 mrem
- max exposure pregnancy is <500 mrem
protection against nonionizing radiation
- eyewear
- nonreflective instruments
- distance does NOT help
- cover patients eyes with moistened gauze and exposed skin with wet towels
- decrease % of O2 used to 30%, no use of nitrous
- filter mask to prevent intake of the plume (cellular debris)
