Physics Flashcards
What are the units of force?
N (kg⋅m/s^2)
What are the units of work/energy?
J (kg⋅m^2/s^2)
What are the units of power?
W (kg⋅m^2/s^3)
What are the units of velocity?
m/s
What are the units of acceleration?
m/s^2
What are the units of density?
kg/m^3
What are the units of electric field
N/C
What are the units of current?
C/s
Vector vs. scalar?
Vector: quantity that has magnitude and direction (displacement, velocity etc.)
Scalar: quantity that has magnitude only (distance, speed etc.)
How do you add vectors?
Tip to tail (place tip of A to tail of B, then line from tail of A to tip of B)
X vector component vs. Y vector component? Pythagorean?
x = vcosθ
y = vsinθ
If given x and y: x^2 + y^2 = v^2
Displacement vs. distance? Graph?
Displacement: vector quantity, accounts for only the net traveled (final - initial)
Distance: scalar quantity, accounts for total pathway
Area under curve of v vs. t graph
Velocity vs. speed? Equation?
v = Δx/Δt
Forces are vectors or scalars? Gravitational, equation? Friction, equation? Normal?
Forces are vectors
Gravitational force is an attractive force Fg = Gm1m2/r^2
Frictional force opposes the movement of objects Ff = μkN
- static: for stationary objects (μs > μk)
- kinetic: for moving objects
Normal force is the component of force b/w objects that is perpendicular to plane of contact
What is acceleration, equation?
Vector quantity, result of a net force applied a = Δv/Δt
Mass vs. weight?
Mass: scalar quantity that is the measure of matter in an object
Weight: vector quantity that is the measure of the gravitational force on a mass Fg = mg where g = 10m/s^2
What is Newton’s First Law? Second Law? Third Law?
First: F = ma, an object at rest or in motion at constant velocity will remain unless a net force is applied
Second: acceleration only occurs when there is a net force
Third: Force of A on B = - Force of B on A, action/reaction with equal but opposite force between objects
What are the two main linear kinematic equations? What about time up, time down, max height?
v = v0 + at
Δx = v0t + 1/2at^2
time up = time down
@max height, v = 0
What is centripetal force?
Force in the radial direction to prevent objects from spinning out Fc = mv^2/r
What is the torque equation?
τ = rFsinθ, CW is (-), CCW is (+)
What is energy? Kinetic energy? Potential energy, gravitational + elastic? Conservation?
KE = 1/2mv^2
Gravitational PE = mgh
Elastic PE = 1/2kx^2
Wnc = KE + PE (so usually KE = PE, if no friction)
Conservative vs. non-conservative forces?
Conservative: path independent, doesn’t dissipate energy
Non-conservative: Friction (heat)
What is work, equation? P-V equation?
W = Fdcosθ (angle of OBJECT movement)
W = PΔV or area under curve of P-V graph
Work done by a system is (+)
Work done on a system is (-)
What is power, equation?
P = W/Δt = F⋅v
What is mechanical advantage, equation? Efficiency?
ME = F out, without machine / F in, with machine
Efficiency = W out / W in
What is temperature? K vs. C? Heat?
Temp is proportional to the average KE
K = C + 273, 0 K is considered absolute zero
Heat is the transfer of thermal energy b/w objects
Isolated vs. closed vs. open system?
Isolated: no exchange of energy or mass
Closed: exchange of energy but not mass
Open: exchange of both mass and energy
What is the internal energy equation or first law of thermodynamics?
ΔU = Q - W
U = internal energy of system, (+) when temp increases
Q = heat energy, (+) when heat enters system
W = work, (+) when work is done by system
Conduction vs. convection vs. radiation?
Conduction: transfer of heat through direct contact of objects and molecular collisions
Convection: transfer of heat by physical motion of a fluid over a material (liquids, gases)
Radiation: transfer of heat by EM waves
What is the specific heat equation?
Q = mcΔT
What are the different phase changes? Temperature they occur at? Equation?
Solid –> liquid: melting/fusion
Liquid –> gas: vaporization
Gas –> liquid: condensation
Liquid –> solid: freezing
Solid –> gas: sublimation
Gas –> solid: deposition
Phase changes occur at a constant temperature
Q =mL
L = latent heat
Isovolumetric (isochoric) vs. isothermal vs. isobaric vs. adiabatic
Isovolumetric (isochoric): at a constant volume
Isothermal: at a constant temperature
Isobaric: at a constant pressure
Adiabatic: no heat exchange (steeper than isothermal on a P-V graph)
Fluids vs. solids?
Fluids: ability to flow and conform to shape of container
Solid: do not flow and are rigid enough to retain shape independent of container
What is the density of water?
1,000 kg/m^3 or 1 in other units
What is specific gravity?
SG = p of thing / p of water = % submerged
determines if an object will sink or float by comparing density to water
What are the units of pressure?
P = F / A Pa = N/m^2
In Pa, mmHg, atm, Torr 1 atm = 1 torr = 760 mmHg
What is hydrostatic pressure in terms of submerged, equation?
Pressure exerted on an object submerged in water
P = pgz
p = density, g = gravity, z = depth of object
What is gauge pressure, equation?
Pgauge = P - Patm
Difference b/w hydrostatic pressure inside and atmospheric pressure outside
What is Pascal’s Principle, equation? Think hydraulics
F2 = F1(A2/A1)
Apply force F1 to an area A1 which transmits force to other side with greater area A2 which results in greater upward force F2
Output side moves a smaller distance than input side
What is Archimede’s Principle, equation? Think buoyancy
Fbuoyant = p(fluid) V(fluid displaced) g
Volume of fluid displaced = volume of object
Buoyant force is equal to the weight of the fluid it displaces
Surface tension vs. cohesion vs. adhesion?
Surface tension: the thin but strong layer formed at the surface of a liquid
Cohesion: the attractive force b/w molecules of same liquid that results in surface tension
Adhesion: the attractive force b/w molecules of different substances (think the wall of a container)
What is viscocity?
The resistance of a fluid to flow (thick, sticky)
Laminar vs. turbulent flow?
Laminar: smooth and orderly flow parallel to each other that is fastest in the middle away from walls (adhesion to wall slows velocity)
Turbulent: rough and disorderly flow that happens when the critical speed is exceeded (if travels too fast = turbulent)
What is the equation of continuity or VFR?
VFR = A1v1 = A2v2
Faster flow results in decreased area b/c conservation
What is the venturi effect?
Areas of increased speed are also areas of reduced pressure
What is Bernoulli’s equation?
Too long, refer to something
Proton vs. electron? Mass? Repel/attract?
Protons have much greater mass than electrons
Like charges repel, opposite charges attract
Insulators vs. conductors
Conductors: metal, charge distributes evenly across surface! (where free electrons are) and can transfer charge
Insulator: nonmetals, charge not even distributed over surface and is not transferrable to another object
What is coulomb’s law/electric force?
Fe = Kq1q2/r^2
What is an electric field? Equation? Field lines? Force on a charge?
A field that is set up by electric charges, they exert a force on other charges that move into the field (so it accelerates particles)
E = Fe/q = Kq/r^2 or E = v/d in V/m or N/C
Originate at positive charges and terminate at negative charges
F =qE
What is electric potential energy? Equation?
PE = qV in joules (J)
What is electric potential?
V = Kq/r in volts (V)
What is current?
I = q/Δt, in amps (C/s) charge transmitted by flow of electrons
What are Kirchoff’s Laws?
Junction: Current into junction is equal to current leaving junction
Loop: Voltage of the source is equal to voltage drop
What is resistance? Equation? Temperature effect?
R = pL/A
R = resistance p = resistivity (inverse of conductivity) L = length A = area
Increased temperature increases resistance
Increased area reduces resistance
What is Ohm’s Law?
V = IR
What are the power equations?
P = IV = I^2R = V^2/R
What is a capacitor? Equation? PE of a capacitor equation? What is the effect of area/distance?
Stores energy in the form of separated charges on parallel plates that can rapidly discharge
C = q/V in C/V q = cV
PE = 1/2CV^2
C = E0(A/d) so increased distance b/w plates reduces capacitance and increased area of overlap increases capacitance
Resistors vs. capacitors in series vs. parallel?
Resistors in series: Req = R1 + R2 (current carries)
Resistors in parallel: 1/Req = 1/R1 + 1/R2 (voltage carries)
Capacitors in series: 1/Ceq = 1/C1 + 1/C2 (charge carries)
Capacitors in parallel: Ceq = C1 + C2 (voltage carries)
Transverse vs. longitudinal wave?
Transverse: direction of oscillation is perpendicular to the propagation of the wave (EM waves)
Longitudinal: direction of oscillation is parallel to the propagation of the wave (sound waves)
How do you relate velocity, wavelength, frequency?
What is period?
What is angular frequency?
What is amplitude?
v = λf
λ = distance b/w one maximum and another f = number of wavelengths through a point per second (Hz)
T (period) = 1/f or the number of seconds per cycle or wavelength
w = 2πf = 2π/T
Amplitude: maximum magnitude of displacement from center to a maximum
What is in-phase vs. out-of-phase? CI vs. DI?
In-phase: when the maximums and minimums of two waves line up
Out-of-phase: when the maximum of one wave matches the minimum of another wave with λ/2 or 180 degree phase difference
CI: perfectly in phase waves sum together
DI: out-of-phase waves cancel each other
Traveling vs. standing wave? node vs. anti-node?
Traveling: fixed on one side, reflects back
Standing: fixed on both sides, appears stationary
Node: area of zero amplitude
Anti-node: area of max amplitude
What is the equation for speed of sound through a medium?
v = sqrt(B/p)
B = bulk modulus p = density
So sound is fastest in solids and slowest in gas or non existent in a vacuum
What is attenuation?
The dampening of the intensity of sound that is greatest in soft materials
What is the doppler effect equation?
Refer to equations
What is the sound intensity equation? Decibel equation?
I = P/A or power over area (higher rate results in higher intensity)
Decibel = 10log(I/I0) I0 = threshold of hearing
On a log scale so 1 is ten, 2 is hundred, and 3 is thousand
Ultrasound vs. doppler ultrasound?
Doppler ultrasound can measure blood flow
What is the EM spectrum?
Refer to notes
Raging martians invaded venus using x-ray guns
Reflected angles are..?
Equal to each other, θ1 = θ2
What is refraction, equation? Snell’s Law? TIR? Frequency change?
The bending of light as it passes from one medium to another and changes speed… Frequency does NOT change between mediums…. Light is slower in a dense medium because it is absorbed by atomic structure and the wavelength is shorter so frequency stays the same
n = c/v n = index of refraction, c= speed of light, v= speed in medium
n1sinθ1 = n2sinθ2
n1>n2: bend away from normal
TIR: when n1>n2
What is a real vs. virtual image?
Real: light actually converges here
Virtual: no light actually converges here
Concave/convex mirror/lens?
Concave mirror: converging
Convex mirror: diverging
Concave lens: diverging (for nearsighted, myopia)
Concave lens: converging (for farsighted, hyperopia)
What is the optics equation? Focal length and radius equation? Magnification equation?
1/f = 1/o + 1/i f = focal length (+ for converging, - for diverging) o = object distance i = image distance
f = r/2
m = -i/o -m: inverted image (always real) \+m: upright image (always virtual) absvalue(m) > 1: enlarged image <1: reduce image
Polarization is how many degrees out of phase?
90 degrees
What is the photoelectric effect equation?
If light is a high enough frequency electrons are excited enough to be ejected
E = hf = hc/λ
E = energy of photon, proportional to KE of ejected electron
E = mc^2
What is atomic notation?
top (A)
bottom (Z) X
A = mass number (neutrons + protons) Z = atomic number (protons) X = the element
What are the types of radioactive decay?
Decay to formation of daughter nuclei
Alpha decay: emission of two neutrons and two protons (alpha particles are big)
Beta- decay: conversion of neutron –> proton and emission of an electron (electron capture)
Beta+ decay: conversion of proton –> neutron and emission of a positron
Gamma decay: emission of high energy photons (charge-less and mass-less)
What is the lens power equation?
P = 1/f (focal length)
1/f = 1/f1 +1/f2
P = P1 + P2
m = (m1)(m2)
Pipe open at both ends equation vs. open at one end?
Open at both: L = λ/2
Open at one: L = λ/4
What is the magnitude of a magnetic field equation?
F = qvB
