Download AP Physics B Content Outline

AP Physics B Content Outline
NOTE – this is not an all inclusive review. This is just the highlights and helpful
reminders for each unit. Go back and study notes, practice problems, quizzes and tests to
prepare for the AP exam.
I.
Newtonian Mechanics (35%)
a. Kinematics (7%)
i. Motion in one dimension - includes vectors, coordinate systems,
displacement, velocity, acceleration
Velocity = distance/time
Acceleration = velocity/time
3 main equations
Vf = Vi + at
Vf^2 = Vi^2 + 2ax
X = Vit + ½ at^2
ii. Motion in two dimensions – sine, cosine, trig, x velocity stays
constant and zero acceleration, y acceleration is -9.8 m/s^2
Position – time graphs  slope is velocity
Velocity – time graphs  slope is acceleration, area under curve is
displacement
b. Newton’s laws of motion (9%)
i. Static equilibrium (first law – object in motion stays in motion,
object at rest stays at rest unless acted upon by an unbalanced
force)
ii. Dynamics of a single particle (second law – f = ma)
iii. Systems of two or more bodies (third law – equal and opposite
forces)
Examples: two boxes pushing each other, solving a system for
contact force, frictional force, applied force
When in doubt draw a free body diagram
Frictional force = coefficient of friction * normal force
Inclined planes  mg always acts downwards and will be resolved
into two vectors, use same angle as incline
c. Work, energy, power (5%)
i. Work and work-energy theorem
Work = force*distance
Work = change in KE
ii. Conservative forces and potential energy
PE = mgh, KE = ½ mv^2
iii. Conservation of energy: KE1 + PE1 = KE2 + PE2
iv. Power
P = work/time
P = Fv
Units  energy is joules, work is joules, power is watts
d. Systems of particles, linear momentum (4%)
i. Center of mass  momentum = mv
ii. Impulse and momentum 
Impulse is change in momentum
Ft = m*∆v
iii. Conservation of linear momentum, collisions
Elastic collision: m1v1 + m2v2 = m1v1’ + m2v2’, kinetic energy
conserved
Inelastic collision: m1v1 + m2v2 = v’(m1 + m2), deformation
occurs, and energy is lost
Recoil: 0 = m1v1’ + m2v2’
e. Circular motion and rotation (4%)
i. Uniform circular motion  F = mv^2/r
Centripetal acceleration always acts toward center of circle
Velocity is always tangent to the circle
Don’t put centripetal force on a free body diagram
ii. Torque and rotational statics  meter stick and balancing weights
lab,
multiply force * distance on each object and add all objects together
on each side of meter stick
You will be solving for distance to the object or the weight of the
object
Be careful whether you are solving for mass or weight and what the
question is asking for
Pulleys  the larger weight will be moving downwards
Mg – T = ma or T – mg = ma
Might need to combine with kinematics equations to solve for
distance an object falls or time it takes to fall
f. Oscillations and gravitation (6%)
i. Simple harmonic motion (dynamics and energy relationships)
Elastic potential energy = ½ kx^2
1/f = T, 1/T = f, freq = cycles/sec
Frequency units  hertz
Period units  seconds
F = -kx (Hooke’s law) force is always in opposite direction from
displacement
ii. Mass on a spring
Period of a mass and spring = 2*pi*sqrt(m/k)
iii. Pendulum and other oscillations
Period of a pendulum = 2*pi*sqrt(l/g)
**mass does NOT affect the period of a pendulum
iv. Newton’s law of gravity
F = Gm1m2/r^2
Everything has a gravitational force between them, its most
noticeable when we are referring to planets.
G is on your constant sheet
Another equation for period is T = (2*pi*R)/vel
v. Orbits of planets and satellites
Kepler’s Laws
1st – every planet moves with an elliptical orbit
2nd – as planet moves in its orbit, a line drawn from the sun to the
planet sweeps out equal areas in equal time intervals
3rd – if T is the period and a is the length of the axis of the planet’s
orbit, the ratio of T^2/a^3 is the same for all planets
Satellite speed = sqrt(GM/R)
II.
Fluid Mechanics and Thermal Physics (15%)
a. Fluid Mechanics (6%)
i. Hydrostatic pressure
The pressure is the same as long as it’s the same depth
P = F/A , density = mass/volume
P = pgh
Pabs = Patm + pgh
Patm = 1 x 10^5 Pa = 1 atm
ii. Buoyancy
Archimedes Principle - Weight of displaced fluid is equal to
buoyant force
W = Vgp
iii. Fluid flow continuity
Volume flow rate = velocity * area, as area goes up velocity will
go down
iv. Bernoulli’s equation
P1 + pgy + ½ pv^2 = P2 + pgy2 + ½ pv2^2
Most common examples are the big tank with a hole in the side
and calculate the velocity of the water
Bernoulli affect – when velocity is very high, pressure will be low
Ex: airplane, perfume bottle, Frisbee
b. Temperature and heat (2%)
i. Mechanical equivalent of heat
C = 5/9 (F – 32)
F = 9/5*C + 32
Heat – thermal energy that is being transferred fro one object to
another
Specific Heat  Q = mc∆T
Q = heat, c = specific heat, T = temperature, m = mass
Efficiency = (1 – heat out)/heat in
Efficiency = work/heat in
ii. Heat transfer and thermal expansion
Linear thermal expansion  ∆l = αl∆T
c. Kinetic theory and thermodynamics (7%)
i. Ideal gases
1. kinetic model
KE = 3/2 kT
2. ideal gas law
III.
PV = nRT
ii. laws of thermodynamics
1. first law (including processes on PV diagrams)
First law of thermo  U = Q + W
U = internal energy, Q = heat, W = work done on/by the
system
Internal energy only depends on Temperature according to
U = 3/2nRT
4 processes
Abidiatic – heat in = heat out
Isochoric – volume constant , no work done
Isothermal – temperature constant
Isobaric – constant pressure
Work = area under curve
The steeper the slope, the higher the temperature
Electricity and Magnetism (25%)
a. Electrostatics (5%)
i. Charge, field and potential
Field always flows out of positive and into negative
Field inside a conductor is zero, all charger is distributed on outer
edge
Field is always perpendicular to surface
E = F/q
E = kQ/r^2
E = V/d
Do not include charge sign when calculating field or force
Find directions by looking at a diagram and deciding if charges are
attracting or repelling
Electric potential energy= V*q
PE = kq1q2/r
Potential energy = work
K = 9 x 10^9
K might also be seen as ¼*pi*e
Potential difference = voltage
V = kQ/r
ii. Coulomb’s law and field and potential of point charges
Coulomb’s law  F = kq1q2/r^2
iii. Fields and potentials of other charge distributions
Ex: three charges in a row, which way does the overall field or force
point
b. conductors and capacitors (4%)
i. parallel plate
Capacitors store charge, one plate is positive and the other is
negative
The smaller the distance between the plates, the more the
capacitance
Capacitors  units are farads, often seen as microfarads
C = Q/V
C = eA/d  e is constant = 8.85 x 10^-12
c. Electric circuits (7%)
i. Current, resistance, power
V = IR
Voltage  volts
I = current  amps
R = resistance  ohms
Resistivity  R = pl/A
Power  watts
Power = VI = V^2/R = I^2*R
Resistors add when in series, and current is constant across series
Resistors combine by formula in parallel and voltage is constant
ii. Steady state direct current circuits
Kirchoff’s rules
1st – Kirchoff’s voltage rule – sum of potential differences must
equal zero
2nd – Kirchoff’s Current rule – all current coming into a node must
equal all current leaving the node
iii. Capacitors in circuits
Capacitors in parallel will add
Capacitors in series will combine using the formula 1/C +1/C2 =
1/Ctotal
Capacitors in parallel have same voltage across all
Capacitors in series have constant charge across all
d. Magnetic fields (4%)
Field lines flow North to south
Poles can’t be isolated because of continuous current lines
i. Forces on moving charges in magnetic fields
Magnetic field and velocity/current always act in the same plane and
force will act at a 90 degree angle
3 right hand rules
1  thumb is velocity or current, first finger is magnetic field,
middle finger is magnetic force
2 thumb points in direction of current, fingers curl in direction of
magnetic field
3  thumb points in direction of magnetic field, and fingers curl in
direction of induced current
ii. Forces on current carrying wires in magnetic fields
F = iLB  force on a current carrying wire
F = qvB  force on a charge
iii. Fields of long current carrying wires
B = uI/2*pi*r
U = 1.257 x 10^-6
e. Electromagnetism (5%)
i. Electromagnetic induction (faraday’s law and Lenz’s law)
Flux = area * magnetic field
Faraday’s law  emf = flux/time
Emf = Blv
This is only the emf in one loop, if the coil has multiple loops,
multiply by the number of loops or turns
The quicker the change in magnetic field, the stronger the induced
voltage
Lenz’s law – a current can be induced in a closed loop when
magnetic flux is changing
Systems don’t like change, current will be induced to oppose the
change in flux
IV.
Waves and Optics (15%)
a. Wave motion (including sound) (5%)
i. Properties of traveling waves
Wave terminology  crest, trough, amplitude, frequency,
wavelength
Sound is longitudinal and light is transverse, remember light waves
can be polarized
Transverse – wave moves up and down
Longitudinal – wave moves back and forth
Speed = wavelength * frequency
Wave speed in standing wave = sqrt(tension/u)
u = mass of string/length of string
ii. Properties of standing waves
Node and antinode, string is attached at both ends
Wavelength = 2L/n
Frequency = nv/2L
n = number of loops
L = length of rope
full loop is half a wavelength
Resonant frequency  one loop
When tube is open at one end and closed at the other
F = nv/4L
Wavelength = 4L/n
Sound waves  beat frequency – difference between frequencies,
how many times is it in phase every second
iii. Doppler effect – relative motion of sound and observer, detect
different frequencies
If source is moving toward observer, hear a louder sound
If source moving away from observe, hear a softer sound
4 equations, two for when source is moving, two for when observer
is moving
iv. Superposition – two waves occupy the same space at the same time
Destructive interference – crest meets trough and wave disappears
Constructive interference – crest meets crest and waves grows
b. Physical optics (5%)
i. Interference and diffraction
Young’s Double slit experiment – showed the wave nature of light
because a series of light and dark bands appeared on the screen
This showed the constructive and destructive interference of light
waves
Equation  wavelength = dx/mL
d = distance between slits
x = distance between light bands
m = how many light bands are we talking about
L = distance from screen to slits
Wavelength is related to distance between light bands, if one goes
down so does the other
ii. Dispersion of light and the electromagnetic spectrum
Ranges from radio waves with very long wavelengths to gamma
waves with very short wavelengths
Visible light is the colors we see
ROY G. BIV – red has longest wavelength and shortest frequency
and violet has shortest wavelength and greatest frequency, both
travel at the speed of light
c. Geometric optics (5%)  see below
i. Reflection and refraction
ii. Mirrors – reflection
iii. Lenses – refraction
V.
Atomic and Nuclear Physics (10%)
a. Atomic physics and quantum effects (7%)
i. Photons, photoelectric effect, Compton scattering, x-rays
Photoelectric effect – photons emitted from a light source hit a metal
plate, all energy is transferred to an electron. The electron uses part
of the energy to escape (work function) and part turns into KE.
Eph = KE + work function
Photons – unit of electromagnetic energy
Two different Planck’s constants, one is in J*s and the other is in
eV*s. Either one is acceptable as long as it is used consistently and
the correct units are put with it.
Einstein told us that Photons don’t have mass.
ii. Atomic energy levels
The more the energy level, the shorter the wavelength
Photon energy can be thought of as the difference in energy levels
E = hf
E = hc/wavelength
E = pc
p = h/wavelength
Bohr Model – told us how electrons orbited around a nucleus. An
electron must move from a high energy to a low energy to emit a
photon and an electron can only move to a higher energy level if it
absorbs some energy.
iii. Wave-particle duality
Everything has wave particle duality. However if something has a
very large mass, its particle qualities overrun the wavelength
qualities so we don’t notice it. If something is very small then
wavelength and particle nature have to be considered.
b. Nuclear physics (3%)
i. Nuclear reactions
Atomic number  number of protons
Atomic mass  total number of protons and neutrons
Conservation of nucleons – even though protons can turn into
neutrons and vice versa, the total number of both combined will
remain the same.
Nuclear Fission – Atom breaking into smaller pieces, but those
pieces in mass won’t add up to the total original mass of the atom,
some mass has changed into energy by Einstein’s equation
ii. Mass-energy equivalence
E = mc^2
Optics review sheet
Mirrors
Convex – image always virtual, upright, reduced
Concave
Distance
Further than 2f
2f
Between 2f and f
F
Between f and
lens
Upright or
inverted
Inverted
Inverted
Inverted
No image
Upright
Size of image
Enlarged or
reduced
Reduced
same
Enlarged
No image
Enlarged
Real or virtual
Real
real
Real
No image
Virtual
Lenses
Converging lens – always thick at the center and thin at the edges
Distance
Upright or
Size of image
Real or virtual
inverted
Enlarged or
reduced
Further than 2f
Inverted
Reduced
Real
2f
Inverted
same
real
Between 2f and f Inverted
Enlarged
Real
F
No image
No image
No image
Between f and
Upright
Enlarged
Virtual
lens
Diverging – always thin in the middle and thick at the edges
images are always virtual, upright, and reduced
Sign Conventions
Mirrors
If object and image are on the same side, the focal length is positive.
If magnification and image height is positive, then the image is upright.
Lenses
If object and image are on opposite sides of the lens the focal length is positive.
If the image distance is positive, the image is on the opposite side of the lens as the
object.
If magnification and image height are positive, then the image is upright.
Equations
Mirror or lens equation
Magnification equation
Index of refraction
n = c/v
Snell’s Law
n1sinθ = n2sinθ
Law of reflection – angle of incidence equals the angle of reflection
The more narrow the angle with respect to the normal to the surface, the slower the speed
of light in the medium
The higher the refraction index the slower light will move through it.
n2>n1
v2<v1