Week 4 Day 2 Flashcards
hydrostatics
study of stationary fluid
w = m * g = p * V * g = P * A * h * g
P = W / A
Pascal’s principle
when an external pressure is applied to a confined fluid, it is transmitted unchanged to every point within that fluid.
P1 = P2
F1 = F2 * (A1/A2)
hydrodynamics
study of moving fluid
Flow = volume/time (m3 /sec)
If flow is constant:
velocity = flow / area
*fluid in a smaller tube will go faster, assuming same flow rate
Bernoulli Equation
An increase in the speed of a fluid occurs simultaneously with a decrease in pressure or in the fluid’s potential energy
P1-P2 = ½d * v12 *((A1/A2)2 -1)
Flow
Flow = A1 * V1 = A2 * V2
Venturi effect
the reduction of fluid pressure when fluid flows through a constricted section of a pipe.
viscosity
describes the fluids resistance to flow.
(mPa)
Poiseuille’s equation
Gives the pressure drop in a flow across a length of tube
Flow = (P1-P2) * π * r4 / (8 * n * L)
n = viscosity
L = length
charge on an electron
1.602 x 10-19 C
1 C = 6.24 x 1018 e
Coulomb
SI unit of electrical charge
1 C = 6.24 x 1018 electrons
one Ampere second
1 Volt / Amp
Coulomb’s Law
F = k * q1 *q2/r2
k = 8.99 x 109 N*m2/C2
F can be + (repulsive) or - (attractive)- opposites attract
electric potential energy
Joule (kg * m2/s2)/ Coulomb
or
Volt
potential energy of two charges repulsing each other. If one is unable to move, the other charge will be repulsed by first charge, giving it potential energy
volt
1 Joule/Coulomb
SI unit for electric potential energy
electric current
1 Amp = 1 Coulomb / second
flow of electric charge, measured in charge/time
conductors
carry electrical current efficiently
*metals are generally good conductors
insulators
resist carrying electrical current
most non metals
Ohm’s law
the voltage driving electrons through a circuit is directly proportional to the volume of electron flow and the resistance of the medium to that flow.
V = IR
I = current (amps)
V= voltage (volts)
R = resistance (ohms)
symbol for resistor
Single pull, single throw
ex. light switch
resistors in series
Rtotal = R1 + R2 + R3…Rn
resistors in paralles
Gtotal = 1/R1 + 1/R2 + 1/R3….
electrical power
power is current times voltage
P (W) = I * V
I= current (amp)
V = voltage (volt)
W = watt
OR J/sec = C/sec * J/C
Electrical Energy
Energy (J) = power (J/s) * time (s)
expressed as kilowatt-hour
1 kWh = 1000 W * hr
Semiconductors
properties of both conductors and non conductors
silicon and germanium
p-type semiconductor
Group IV doped with Group III
leaves a positive hole in structure
n-type semiconductors
Group IV doped with froup V
leaves a negative hole in structure
diode
a p-type semiconductor bound to an n-type semiconductor
*A diode will conduct electricity in one direction, not the other
transistors
use semiconductors to control the current that goes through
(E –> B) current controls current between (E –> C)
(E –> C) current is greater than (E –> B), so it can be used as amplifier
spectroscopy
shining light through, or reflecting light off a material; wavelengths of light that are absorbed by the material will not be transmitted or reflected
Beers law
Absorbance (A) for a wavelength of light depens on the absorbtivity (a) of the material, the concentration (c) and the thickness (b)
A = a * b * c
Alpha decay
loses an 24He.
All elements with atomic numbers greater an 83 experience Alpha decay.
Beta- decay
Neutron turns to proton and kicks out an electron an antineutrino
Beta + decay
proton turns to neutron and kicks out a positron
*used for PET scans
half life
time it takes for half a radioactive material to decay
N(t) = N(0) * e-(decay constant * t)
Planck’s constant
E = h * c/(wavelength) = h * f
f = frequency
c = speed of light
decay rate
number of radioactive decays or disintegrations occurring per unit time
SI unit becquerel (bq)
1 Bq = 1 disintegration/sec
Curie (Ci)
1Ci = 3.7 x 1010 Bq
