Physics principles Flashcards
What is the triple point of water?
the triple point of water is the specific temperature and pressure at which all three phases are in equilibrium at:
Pressure: 611.73 pa (0.00604 atm)
Temp: 273.16 K or 0.01 °C, or 32.018 °F
celcius to farenheit estimate equate (normally out by few degrees)
degrees C x2 + 30
actual values:
0°C ≈ 32°F (freezing point of water)
10°C ≈ 50°F
20°C ≈ 68°F
30°C ≈ 86°F
40°C ≈ 104°
What is the only thing that affects SVP of a volatile?
Define SVP
Temperature
Key Features of SVP:
Equilibrium Condition:
SVP occurs when the rate of evaporation of molecules from the liquid phase equals the rate of condensation back into the liquid phase.
Temperature Dependence:
SVP increases with temperature because more molecules have enough energy to escape from the liquid phase into the vapor phase.
At the boiling point, SVP equals the surrounding atmospheric pressure.
Units:
SVP is usually expressed in units of pressure, such as pascals (Pa), millimeters of mercury (mmHg), or atmospheres (atm).
Substance-Specific:
Each substance has a unique SVP at a given temperature. For example, water at 25°C has an SVP of approximately 23.8 mmHg (3.17 kPa).
What is the equation for calculating voltage?
V=IR
Basic positive exponential equation & graph
y =e^x
basic negative exponential equation & graph
y=e^-x
Clinical tear away positive exponential equation & graph
y=a.e^kt
This can be seen in early stages of bacterial replication
physiological negative exponential equation & graph
y=a.e^-kt
line is asymptotic to the x axis.
seen in processes such as drug elimination & lung volume during passive expiration
physiological build up negative exponetial equation & graph
y=a-b.e^-kt
(graph shape- imagine negative exponetial being flipped upside down)
Negative exponential despite increase, because the rate of increase in y is decreasing as t(time) increases
e.g- wash-in curve, or lung volume during positive pressure ventilation using PC vent
list atmospheric pressure in different units
101.325 kPa
101,325 Pa
1 Atm
760 mmHg or Torr
1.01325 bar
14.7 psi
1.define half life (t 1/2)
2. what is the time equivalent of half life
3.examples of processes where half life is useful
4. When is an exponential process said to be complete?
- the time taken for the value of an exponential function to decrease by half.
- time equivalent of half life is 0.693.t (tau)
NB: In(2) [the natural log of 2]= 0.693
3. used in radioactive decay & pharmacokinetics (time taken for plasma conc of drug to reduce by 50%)
4. An exponential process is said to be complete after 5 half lives (96.875 of the process has occurred)
1 half life:50% remains
2: 25% remains
3. 12.5% remains
4. 6.25% remains
5. 3.125% remains 100-3.125%= 96.875 complete
- define time constant
- what value does it represent a fall to
- can also be defined as the time take for the value of an exponential function change by a factor of ….?
- whats the relationship between time constant and rate constant
time constant is the time it would have taken for a negative exponential process to complete, had the initial rate of change been maintained throughout. given by the symbol t(Tau)
2. time constant is the time for the value to decay to approximately 36.8% of it’s initial value.
3. change by a factor of e^1
- time constant is the reciprocal of the rate constant
which is shorter, half life or time constant?
half life is always shorter than time constant
t1/2 =0.693.t(tau)
Name the Seven SI units
SMMACKK:
-Second: measure of time (duration of a given number of oscillations of the caesium-133 atom.
-Meter: distance (length of path travelled by light in vacuum during a certain fraction of a second
-Mole: amount (of substance which contains a many elementary particles as there are atoms in 12g of carbon 12.
Ampere: measure of current: the current in two parallel conductors of infinite length placed 1 meter apart in a vacuum, which would produce between them a force of 2 x 10^-7 N/m-1
Candela: luminous intensity- in a given direction, of a source that emits monochromatic light at a specific frequency
Kilogram: Mass- the mass of international prototype of the kilogram held in Sevres, France
Kelvin: Temperature. 1/273.16 of the thermodynamic temperature of the triple point of water
relationship between, pressure, force and are
pressure=force/area
force=PxA
what is the equation for kinetic energy
1/2mass x velocity^2
how can energy be defined
Energy is measured in joules (J).
Energy is force × length (m) (1 J = N.m). Energy is also a function of pressure (Pa) and volume (V) (1 J = 1 Pa.m3).
Energy = work or power (W) x time.
e.g 1J=W.s
What is acceleration?
acceleration is the rate of change of velocity (m/s^2)
a(m/s^2)=change in velocity (m/s) /change in time (s)
Force=mass x acceleration (FMA)
or newtons 2nd law a=F/m
define boyles law?
Pressure=1/volume
as volume of a gas decreases, its pressure will increase.
Temperature remains constant
define charles law
at a constant pressure, the volume of gas varies with its absolute temp (as temp increases, volume increase)
define force
that which changes or tends to change the state of rest, or motion of an object
