Test 2 Flashcards
Define Work? What is the formula for work?
Work is defined as a measurement of force displacing an object:
W = F x d (Work is equal to force x distance)
What is the SI unit of measurement for Work?
Joules
Other ways of expressing 1J?
1) 1J = N x m
2) 1J = kg x m^2/s^2
If you have 1kg mass you want to accelerate at 1m/s^2 over a distance of 1m. How much energy do you need?
Since W = F x d and F = m x a;
Then W = (m x a) x d
W = (1kg x 1m/s^2) x 1m = 1J or 1kg/m^2/s^2
How much work was done in Joules lifting a 100kg patient up to a distance of 0.02m straight up to place him onto the operating table?
Since W = F x d;
1st change weight into newtons because weight is acted upon by gravity which is newtons. So, 100kg = 981N, (1kg = 9.81N)
Now, w = 981 X .02 = 19.62J (rounding up gives you 20J or 2 x 10^1J
Define Kinetic Energy? what is the formula for it?
Kinetic Energy is described as energy of motion or the energy a mass has by virtue of being in motion.
KE = 1/2 mass x velocity (KE = 1/2kg x (m^2/s^2))
What is the SI unit of measurement for Kinetic Energy?
Joules or (kg/m^2/s^2); same as Force
What is the KE of a 55kg mass moving at 3.87 meters per second?
KE = 1/2m x velocity^2 KE = 0.5 x 55kg x (3.87m/s^2) KE = 27.5kg x 14.97m^2/s^2 KE = 411.675J
What is the formula used to find the Work done by expanding gas?
W = P x ΔV
What is the formula used to find the volume of a cylinder?
V = A x h (Volume = area x height)
What is the SI units of measurement for volume?
m^3
How many Liters in 1 m^3?
1000L
How much work is done when 2.5L of gas expands to 3L against 600 Pa?
Since W = P x ΔV or W = P x (final volume - initial volume). Since 3L = .003m^3 and 2.5L = .0025m^3; then
W = 600 Pa x (3 x 10^-3m^3 - 2.5 x 10^-3m^3)
W = 600 Pa x (.0005)
W = 0.3 Pa x m^3
W = 0.30J (1J is equal to 1 Pa x m^3)
How much work is done when a ventilator increases the volume of air in the body by 500mL using 600Pa of pressure?
W = P x ΔV W = 600Pa x .0005m^3 = .3J
Define Calorie?
A calorie is the amount of energy necessary to raise 1 gram of water 1 degree Celsius.
Whats the difference between a calorie and a Calorie?
Food Calories are actually kilocalories, written with a capitalized “C”. So, one Calorie = 1 kilocalorie or 1000 calories.
How many Joules are in 1 calorie?
1kcal (1000 calories) = 4184J or
1J = .239 calories
How many Joules in a 2000kcal daily diet?
.239cal/1J = 2000kcal/xJoules. --> .239x = 2000kcal (2,000,000 calories) --> x = 8,368,200J or 8.368 x 10^6J
If a 1500kg truck is traveling down the highway, how fast (v) must it be going to have the same energy as 2000kcal?
KE = 1/2m x v^2 --> V^2 = 2KE/m v = sq. root of 2KE/m v = sq. root of 2(8.37 x 10^6J)/1500kg v = 106m/s or 237mph
Convert 106m/s to mph
1609m = 1 mile and 3600 secs in and hr 1690/106 = 15.17miles 3600secs/15.17miles = 237mph
Define Potential Energy? Give examples?
Energy that is stored by virtue of position (expressed in Joules). i.e.:
1) An airplane in the air
2) Chemical energy stored in food, glucose, or fat
Define Internal Energy? How is Internal Energy represented in an equation?
The sum of all the kinetic energy and potential energies of the particles in a system. It results from the state of the particles at the molecular level.
Represented by the letter “U”
Define Thermodynamics?
The study of how energy is converted from one form to another, and how it flows into and out of a system. A system could be a test tube, a gas cylinder, a patient, etc.
What are the 4 Laws of Thermodynamics?
1) The Zeroth Law of Thermodynamics
2) The First Law of Thermodynamics
3) The Second Law of Thermodynamics
4) The Third Law of Thermodynamics
What is the Zeroth Law of Thermodynamics?
Says that if 2 systems are in a thermal equilibrium with a third system, then they are thermal equilibrium with each other.
Therefore, if the temperature of A = B, and B = C, then A =C.
What is the First Law of Thermodynamics?
The change in Internal Energy (U) of a system of heat (Q) flowing in or out of the system; and work (W) done by or on the system. (ΔU = Q - W) but is written as (ΔU = Q + W)
Why is the 1st Law of thermodynamics written as ΔU = Q - W instead of ΔU = Q + W?
Because heat and work can be added into or taken out of the system.
If Q > 0, the process is endothermic and heat flows into the system (+Q is used).
If Q < 0, the process is exothermic and heat flows into the system (-Q is used).
If W > 0, work done by system on surroundings aka expansion (-W is used).
If W < 0, work done by system on surroundings aka compression (-W is used).
What is the 2nd Law of Thermodynamics?
Says that entropy of the universe is constantly increasing. It does not become spontaneously more organized.
Give an example of the 2nd Law of Thermodynamics?
A mixture of oxygen and nitrous oxide in an anesthesia induction will not spontaneously separate and send only one gas to the patient.
What is the Third Law of Thermodynamics?
Says that it is not possible to lower the temperature of an object to absolute zero.
We have a gas in a cylinder with a frictionless piston. 3J of energy is absorbed in the system. The gas expands to 500mL greater than the original volume against a constant pressure of 600Pa. What are the work, heat, and internal energy changes?
ΔU = Q + W
1st convert SI units for volume ml to m^3
500mL or .5L = .0005m^3,
Since W = P x ΔV,
W = 600Pa x .0005) = .3J
Since there is expansion, the system is doing work and we use (-W) or -0.3 to indicate energy lost from the system.
Q wil be positive (+3) because energy was absorbed into the system.
ΔU = Q + W –> ΔU = +3J - 0.3J –> ΔU = 2.7J
The internal energy of the system increased by 2.7J
Define Specific Heat?
The amount of heat per unit mass required to raise the temperature of something by one degree Celsius.
What is the formula for Specific Heat?
c = Q/m(ΔT).
Hydrostatics
Study of fluids that are not moving
Hydrodynamics
Study of fluids in motion
A beaker with a diameter of 10cm is filled to 20cm with water. If the density of water is 1000km/m^3, how much pressure does the water exert on the bottom of the beaker?
P = dhg (Pressure = density x height x gravity) P = 1000kg/m^3 x 0.20m x 9.81m/s^2 = 1.96 x 10^3Pa
Difference between P= dhg and P2 = P1 +dhg
P2 = P1 + dhg adds the pressure of a gas above a liquid to the equation
What’s the pressure at a depth of 1000m below the surface of the ocean if the density of sea water = 1.03 x 10^3kg/m^3? (remember 1 atm = 101kPa)
P2 = P1 + dhg
P2 = 101,000Pa + (1.03 x 10^3kg/m^3 x 1000m x 9.81) =
1.02 x 10^7Pa
Define Flow? What is the formula for Flow?
Flow is the quantity of fluid passing a point per unit of time.
F = V/t (F = flow; V = volume; t = time)
Formula for Pressure?
P = F x R (P= pressure; F = flow; R = resistance)
How is change in flow annotated?
Q dot (Q̇)
Viscosity
The resistance a liquid offers to motion of a solid through it. (represented by symbol η)
Turdbulence is dependent of what?
Density
Reynolds Number
The point when laminar flow changes to turbulent flow.
< 2000 = laminar flow
2000 to 3000 = a mix btw laminar and turbulent flow
> 3000 = turbulent flow
Describe Laminar Flow
The relationship of flow to pressure. Laminar Flow is steady and smooth without eddies or turbulence.
Turbulent Flow occurs with what?
1) High velocity
2) When tubes are rough
3) At bends or kinks in tubing
(T/F?)Turbulent flow is density dependent, not fluid dependent?
True
Poiseuille’s Law
Describes flow through a tube and how this flow is affected by tube length, radius and fluid viscosity.
Poiseuille’s Law Formula
F = (πr^4ΔP)/8ηl; where F = flow in L/s η = viscosity in Pa/s r = radius of tube in meters l = length of tube in meters
Effect on flowrate when you increase the radius of the tube by 19%?
Doubles the flow rate
Effect on flowrate when you double the radius of the tube?
Increases flow rate by a factor of 16
How do changes in pressure and viscosity affect flow rate?
1) Changes in pressure are directly proportional
2) Changes in viscosity or length are inversely proportional
Using Poiseuille’s Law Formula, calculate aortic blood flow, if blood viscosity = .0015Pas, pressure = 13,000Pa (or 100mmHg) misapplied to the aorta (r - 0.010m; l = 1m).
F = (π x 0.01^4 x 1.3x10^4Pa)/8 x 1.5x10^-3Pas x 1m =.034m^3/s
How does the body apply Poiseuille’s Law to affect BP when needed?
Smaller vessels provide most of the resistance to flow, so arterioles just prior to the capillaries can provide a controlling influence on flow rate, thereby meeting the changing demands for oxygen.
Define Bernoulli’s Principle?
For a non-compressible, non-viscous fluid undergoing laminar flow, the sum of the pressure, kinetic and potential energies per unit volume remains a constant at all points along the line.
Bernoulli’s Principle Formula
ΔP = 1/2d (V2^2 -V1^2)
What is the pressure differential across a flat roof having an area of 240m^2 when the wind blows at 25m/s. (density of air =
ΔP = 1/2d ((V2^2 -V1^2) ΔP = 1/2d (1.29) (25^2-0^2) = 403Pa Since F = P x A F = (403Pa)(240m^2) F = 96,700N or 10.9 Tons of force on the roof from the air inside the house
Fick’s Principle
VO2 = CO x (aO2 - vO2) same as CO = VO2/(aO2 - vO2) VO2 = uptake of O2 by the body CO = cardiac output aO2 = arterial oxygen concentration vO2 = venous oxygen concentration
3 Variables in the Gas Law Equations?
1) Pressure
2) Temperature
3) Volume
Boyle’s Law
V1 x P1 = V2 X P2
V = volume
P = pressure
Charles’ Law
V1/T1 = V2/T2 V = volume T = temperature
Avagadro’s Law
V1/n1 = V2/n2 V = volume n = number of moles
Gay-Lussac’s Law
P1/T1 = P2/T2 P = pressure T = temperature
Ideal Gas Law
- PV = nRT
- R = known gas constant (8.31)
Combined Gas Law
V1xP1/T1 = V2xP2/T2
How is the value for R determined?
- Under a set of standard conditions called “standard temperature and pressure” or STP.
-standard temp = 0c or 273K
R = .0821atm/L/mol/K (old way using atm)
R = 8.31kPa/L/mol/K (new way using kPa)
Based on Avogadro’s Law at STP, what is the volume of 1 mole on any gas?
22.7L
Relationship between volume of gas and the pressure exerted on it (Boyle’s Law)
- Gas is inversely proportional to pressure, if temperature and moles are constant.
- If you increase pressure on the gas, its volume decreases and vice versa
Boyle’s Law Applications
- Ambubag being squeezed
- Pushing syringe against resistance
- Inspiration
- O2 cylinder
Relationship between volume of gas and its temperature (Charles’ Law)
- Volume of gas is directly proportional to temperature
- By increasing the temperature, a gas expands to increase its volume and vice versa
Relationship between volume of gas and number of moles (Avogadro’s’ Law)
- There is a direct relationship
- As number of moles increases, so does the volume of the gas, and vice versa
Avogadro’s number
- The number of molecules in one mole of
- 6.022 x 10^23
Calculate the volume of 12 moles of N2O would occupy at STP?
1mol/22.7L = 12mol/xL –> x = 272.4L
Ideal Gas
- aka perfect gas
- hypothetical gas that consists of particles of zero volume and intermolecular forces
- Real gasses do not exhibit these characteristics
- These characteristics break down at high pressures and low temperatures
Vapor
- When a gas coexist in equilibrium with its liquid
- Molecules are moving from liquid to gas and vice versa at the same rate
- A gas is in equilibrium with its associated liquid
- Follows Dalton’s law of Partial Pressure
Dalton’s law of Partial Pressure
Ptotal = P1 + P2 + P3……
Tripple Point
The temperature and pressure at which it exists simultaneously, in thermodynamic equilibrium, as a solid, liquid, and gas.
- Tripple Point for water = 273.16K or 0.01C
Van der Waals forces
Include attraction and repulsions between atoms, molecules, and surfaces, as well as other intermolecular forces
How many meters in 1 mile
I mile = 1609 meters
Difference between Work and Energy
- Work is the expenditure of Energy
- Energy is the ability to do Work
Units of measurement for work when calculation pressure and changing volume?
- Pressure units = Pascals
- Volume units = Liters
The average kinetic energy of a sample of gas molecules is most closely related to ______?
The temperature of the sample
Official SI units of measurement for Flow
m^3/s
What is the flow rate for the following gauges of IV:
1) 24G
2) 22G
3) 20G
4) 18G
5) 16G
6) 14G
1) 24G - 20mL/min
2) 22G - 35mL/min
3) 20G - 60mL/min
4) 18G - 105mL/min
5) 16G 220mL/min
6) 14G - 330mLmin
