Physics Flashcards
Newton’s 1st Law of Motion
An object at rest or moving at constant speed in a straight line will continue in that state until a net external force acts upon it
Newton’s 2nd Law of Motion
Law of acceleration
Force is equal to mass times acceleration
Newton’s 3rd Law of Motion
For every action there is an equal and opposite reaction
Mass
The total of all matter in an object (sum of electrons, protons, & neutrons)
m=F/a
Weight
Total effect of gravity pulling on all of the electrons, protons, & neutrons
Measure in newtons
Mass x force of gravity= weight
Force of gravity
9.81 m/sec^2
Average Velocity
Displacement/time
Force
The amount of energy required to move an object
F=ma
Dyne
100000th of a newton
The force required to move a 1gram weight 1 cm per second
SVR=
(MAP-CVP)/
(CO) X80
Pressure
P=F/(area)
Pascal
Pa=1N/1m^2
Pa=102g/m^2
KPa=102kg/m^2
1 torr= ?mmHg
1 mmHg
1kPa = ? cm H2O
10.2 cm H2O
1 kPa = ? mmHg
7.5 mmHg
1 mmHg = ? cmH2O
1.34 cmH2O
1 atm = ? mmHg
760 mmHg
1 atm = ? bar
1 bar
1 atm = ? kPa
100 kPa
1 atm = ? cmH2O
1020 cmH2O
1 atm = ? lb/inch^2
14.7 lb/inch^2
When fluid flows through a constricted region of a tube, the velocity of fluid increases and lateral pressure (pressure exerted by the fluid on the walls of the tube) decreases
Venturi’s effect & Bernoulli’s Principle
Laminar vs turbulent flow
Laminar- straight flow
Turbulent- not straight
Poiseuille’s Law
- Flow is directly proportional to the 4th power of radius
- Flow is directly proportional to pressure gradient
- Flow is inversely proportional to fluid viscosity
- Flow is inversely proportional to length of the tube
Resistance to flow (R)
- For laminar flow, R is inversely proportional to the 4th power of radius (>radius, < the resistance) when radius doubled, resistance decreases by 16
- R is directly proportional to blood viscosity
- R is directly proportional to tube length
Reynolds number (Re)
Predicts whether flow will be laminar or turbulent
- Re directly proportional to fluid velocity, tube diameter, and fluid density
- Inversely prop. To fluid viscosity
- Flow changes from laminar to turbulent if > 1500-3000
When turbulent, density, NOT viscosity determines flow
Henry’s Law
Amount of gas that dissolves in a liquid is proportional to the partial pressure
To determine amount of O2 dissolved in blood: PaO2 x 0.003ml (per 100 ml of blood)
To determine amount of CO2 dissolved in blood: PaCO2 x 0.067ml (per 100 ml of blood)
If FiO2 known, estimate PaO2 by multiplying by 5. If FiO2 40% 40x5=200mmHg
Boyle’s Law
Pressure is inversely proportional to volume at constant temperature
If the volume of gas is halved, pressure is doubled
P1V1=P2V2
Ex) squeezing ambu bag raises the pressure & decreases the volume
Charle’s Law
Volume is directly proportional to the absolute temperature at constant pressure
When temperature increases, volume of gas increases
V1/T1=V2/T2
Ex) the inflatable cuff of laryngeal mask airways expands when placed in an autoclave. Balloon shrinks in cold, expands in heat
Gay-Lussac’s Law
Pressure is directly proportional to absolute temperature if volume is constant
When temperature of gas at constant volume increases, pressure increases
P1/T1=P2/T2
Ex) low tire pressure warnings in winter
Generalized Ideal (Universal) Gas Law
Unified findings of Charles, Boyle, & Gay-Lussac
PV=nRT
When cylinder is emptying, the amount of gas (n) is decreasing
As n decreases, P decreases
⬇️PV=⬇️nRT
Dalton’s Law
The total pressure of a gaseous mixture is the sum of the partial pressures
P(tot)= P1+P2+P3…Pn
Ex) PO2 at sea level= 760x21%= 160mmHg
PN2 at sea level= 760x79%= 600mmHg
Avagadro’s hypothesis
One mole of a gas at standard temp (0°C) and standard pressure (1atm) occupies a volume of 22.4L
Law of Laplace (cylindrically shaped structures)
If the radius expands the tension in the wall increases
Ex) aortic aneurysm more likely to rupture than a small capillary
T=Pr
Newtons/cm
Frank-Starling Law
The greater the filling in the left ventricle, the greater the tension in the ventricular wall.
The greater the tension in the wall at end of diastole, the greater the stroke volume
Law of Laplace (spherically shaped structures)
Tension is independent of radius where there is a liquid-air interface
The pressure inside the bubble will change the size
The smaller the radius, the greater the pressure inside the bubble
T=Pr/2
Alveoli without surfactant
ARDS
Wall tension is constant and independent of radius
Smaller alveoli have higher pressure and will empty into larger alveoli causing atelectasis
PH2O at 37°C is?
47mmHg
Fick’s Law of Diffuaion
Directly proportional to pressure gradient, membrane area, and gas solubility
Inversely proportional to membrane thickness and square root of molecular weight
Pressure gradient is the driving force for diffusion
Low blood:gas partition
Rapid rise of partial pressure, rapid transfer of gas from lungs to blood and brain
Rapid onset and recovery
Nitrous oxide
High blood:gas partition
Slow rise of partial pressure, slow transfer of gas from lungs to blood and brain
Slow onset and recovery
Halothane
Work
The expenditure of energy
A force acting through a distance
Kinetic energy
The energy of movement
Potential energy
Stored energy waiting to be used
Ex) compressed gases and chemical bonds
Entropy
The universe’s trend to equilibrate all things
Energy moves from higher concentration to lower concentration
Power
Rate of expending energy
Laws of Thermodynamics
1st- law of conservation of energy: energy cannot be created nor destroyed
2nd- heat spontaneously moves from hot body to cold body
3rd- it is not possible to lower the temp of an object to absolute zero
Coanda Effect
Tendency of fluid flow to follow a curved surface upon emerging from a constriction
Pressure in a fluid
Pressure= density x acceleration due to gravity x height
Pascal’s Principle
The pressure applied to a confined fluid increases the pressure throughout the fluid by the same amount
Law of Laplace (cylinder) equation
T=Pr
Law of Laplace (sphere) equation
T= (P x r)/ (2)
Or
P= (2 x T)/r
Atelectasis in the patient with ARDS is explained by what law?
Law of Laplace
Absolute humidity
The mass of water vapor in a given volume of air
Relative humidity
A ratio of the actual amount of water vapor in the air at a given temperature to the maximum amount of water vapor that the air can hold at that temp.
= ((actual vapor pressure)/(saturated vapor pressure)) x 100
Increases as temp decreases b/c saturated vapor pressure decreases
The PH2O at 37°C?
47mmHg
What does vector analysis determine in an EKG?
Deviation of heart
Mean QRS vector points toward ventricular hypertrophy and away from MI
Newton
The force required to accelerate a 1kg weight 1 meter per second
Energy
The exertion of force (kinetic) or the capacity (potential) to do work