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1. NEW: 2010 Nobel Prize for Physics: http://www.nobelprize.org/nobel_prizes/physics/laureates/2010/
2. Log into http://www.headroyce.org and go to the CLASS PORTAL for assignments, handouts, pdf's, etc.
3. HRS is generating electricity! (Let me know if you are willing to help me analyze the cost/benefit)
Latest Info (latest information can be found here)
Old News (other not-so-new news)
Introduction to AP Physics
Ch.2 - 1-D Motion
Ch.3 - 2-D Motion
Ch.4 - Newton's Laws
Ch.5 - Circular Motion and Gravity
Ch.6 - Work and Energy
Ch.7 - Impulse and Momentum
Parts of Ch.8 & 9 - Rotational Motion, Torque and Equilibrium
Ch.10 - Fluids
Ch. 11 - Vibrations and SHM
Ch. 12 - Sound
Ch. 23 - Reflection & Refraction (+ Ch. 25.2)
Ch. 24 - The Wave Nature of Light
Ch. 16 - Electric Charge and Electric Field
Ch. 17 - Electric Potential, Electric Potential Energy, Capacitance
Ch. 18 - Electric Currents
Ch.19 - DC Circuits
Ch. 20 - Magnetism
Ch. 21 - Electromagnetic Induction and Faraday's Law
Atomic and nuclear physics (coming soon)
Quantum Physics (coming soon)
Start Reviewing for the AP Exam
Physics that makes my head hurt! (gravitons, virtual photons, string theory, etc...Ouch!)
Nobel Prize in Physics 1901 - Present
Nanohigh at Lawrence Berkeley National Lab:
http://www.lbl.gov/msd/highlights/youtube-msd.html?p=954C311769FAF77E (You Tube videos of speakers)
USGS Earthquake Page (interactive map of recent quakes)
USGS Earthquake Preparedness Handbook (written for the San Francisco Bay Area Region)
70% chance of a big quake predicted in the Bay Area between 2000 and 2030 (sfgate.com)
(Original 1999 report from the USGS)
Head-Royce students get some recognition:
Advanced Placement Report to the Nation 2006
(Full Report - see pg 58)
Topic Outline (from CollegeBoard.com)
The AP Physics exam (from the CollegeBoard.com)
Course Description (big pdf)
Table of information (MC & FR) and equation tables (FR, only) (pdf)
Past free response questions (2002 - 2005)
Companion website for our textbook
Ch.2: 1-D Motion
Position, displacement, average speed, average acceleration
Instantaneous velocity and acceleration
Graphing motion (x vs. t, v vs. t, a vs. t)
1-D motion Equations
Simulations & Links:
The Moving Man (JAVA simulation)
......select Motion from the left menu bar, then select The Moving Man
.....(you may have to download the applet to your desktop)
Vector vs. scalar, vector components, vector addition, vector subtraction
The Physics Classroom - Vectors
Ch. 2/3 Test Review: [Test date TBA]
Possible test questions:
- apply 1-D equations
- describe or analyze position, velocity or acceleration graphs (words, slope, area, slope of tangent to the curve)
- freefall (dropped, thrown up, thrown down)
- determine components of a vector (mag & dir)
- add or subtract vectors (using components)
- projectiles (start and stop at same height, end at different height; find time, max ht, ht and velocity at time t)
- boat/plane problems
...... (see worksheets and ch.3 reading)
Review your worksheets, Quizzes and class notes!
... look for the common thread(s) in all of our problems
More Ch.2 Equation Practice (with answers) (someone asked for more practice =))
"Practice Test" - sort of (coming soon)
Ch.4: Newton's Laws of Motion
Inertia, mass & weight
.... Wt. = mg
Free body diagrams (force diagrams)
Newton's 1st, 2nd & 3rd Laws
......."net external Force" = (mass)(acceleration)
...... "net Force" = the sum of all forces on acting the object
...... If A pushes B up, B pushes A down [the forces in an action/reaction pair act on different objects!]
Tension & Normal Force
Multibody problems (the von K. way)
..... F = (coefficient of friction)(normal force)
.... tilting the x & y axes
.... x-comp of wt. = mgsin(theta)
.... y-comp of wt. = mgcos(theta)
.....in most cases (i.e. where friction, wt, and N are the only forces present):
............. net force = (x-comp of wt.) - (force of friction)
Answers to "AP Ch.4 Practice" worksheet
Ch.5: Circular Motion
Uniform circular motion
... constant speed and radius
... the magnitude of the net force and acceleration are constant
... the net force and the acceleration vectors point inward to the center of the circular path
"Centripetal" means "center seeking"
We do not use the "F-word"
.... There is no such thing as centrifugal force!
"Centripetal force" = "net force" = "sum of the force vectors"
Fnet = mac
ac = v2/R
v = 2(pi)r/T
a = gtan(theta)
1. to find acceleration, apply F = ma to the whole system
2. to find tension, apply F = ma to only one object
Newton's Universal Law of Gravity
F = GMm/R2 so: g = F/m = GM/R2
F ~ m (g is ind. of m)
F ~ M g ~ M
F ~ 1/R2 (inverse square law!) g ~ 1/R2
Fnet = Fgrav
mac = mg
ac = g
Apparent Weightlessness (N = 0)
Force, radius, period, velocity and acceleration of orbit
More ch.5 practice
........ More Circular motion practice (answers)
The Physics Classroom - Circular Motion and Planetary Motion
IUN/FYD Introductory Physics Notes
Circular Motion and the Law of Gravity
Companion website for our textbook
energy = the ability to do work
work = change in energy
W = Fd (sort of !)
W = (Fx)(x)
when work is done on a system, it gains energy
when work is done by a system, it loses energy
PE = mgh
KE = (1/2)mv2
EPE = (1/2)kx2 or EPE = (avg force)(dist)
Conservation of Energy:
(initial M.E.)+ (work done on the system) = (final M.E.) + (work done by the system)
If you pick a "system" big enough that their is no net external force acting on the system:
(PE + KE + EPE)i = (PE + KE + EPE)f
In many of our problems with friction:
initial M.E. = final M.E. + work to overcome friction
(PE + KE + EPE)i = (PE + KE + EPE)f + thermal energy from friction
power = rate at which work is done
P = Work/time = (change in energy)/(time)
P = Fv (be careful!)
Units of energy and power:
Energy: Nm, J, calories, Calories (kcal or food Calories), Btu, etc.
Power: J/s, W, kW, hp, calories/sec, etc.
Efficiency = (useful output work)/(input work or energy)
ex: if an engine is 25% efficient, it must burn 400kJ worth of fuel to give the car 100kJ of KE (on level ground with no friction)
(see Student/Teacher Resources)
Work and Energy Animations
Ch.7: Impulse and Momentum
p = m*v
Impulse = F*t = delta p = m*(delta v)
.... "delta" means: "change in" = "FINAL - initial"
p, v, F, delta p, delta v, Impulse are VECTORS!
.... always include a + or - or direction in your calculations!
Conservation of momentum (even when mechanical energy is not conserved!)
.... If you pick a "system" big enough that their is no net external force acting on the system
(see Student/Teacher Resources)
Some Ch. 7 Even answers:
2) - 0.720 m/s
14) 130N; not large enough
18) a) 460 kg m/s East
......b) 460 kg m/s West
......c) 460 kg m/s East
......d) 610 kg m/s East
Chapter 6/7 Test:
Review worksheets, chapter summaries, and problems assigned from the book
Parts of Ch.8 &9: Rotational Motion, Torque and Equilibrium
Angular (or "rotational") velocity and acceleration
.... angular velocity = (change in angle)/time
.... angular acceleration = (change in angular velocity)/time
.... linear velocity = (angular velocity)(r)
.....linear acceleration = (angular acceleration)(r)
Torque = Frsin(theta)
Conditions for equilibrium:
.... net force = 0 (ie: all forces cancel)
.... net torque = 0 (ie: all torques cancel)
Torque = (moment of inertia)(angular acceleration)
rotational KE = (1/2)(momentof inertia)(angular velocity)2
The effect of shape on acceleration down an incline
.... ex: the acceleration of a disc vs. a ring
.... PE = lin KE + rot KE
Semester1 Exam: (Let me know if you have a conflict or qualify for extended time!)
Anything and everything covered so far this year :-)
Possible problems from Chs. 8 and 9 include:
.... equilibrium: net force = 0
.... equilibrium: net torque = 0
.... application of rotational equations for angle, velocity, acceleration and torque
............. see Ch.6-9 Practice (below) and ch.8/9 topics (above)
.... possible surprise question about conservation of energy for a rolling object :-)
See class handouts:
.......Ch.2 - 5 Review
.......Ch.6 - 9 Review
.......Ch.2 - 5 Practice Solutions! (pdf)
Ch.6 - 9 Practice(solutions included!)
Have a great Winter Break!
Ho Ho Ho
Ch. 10 - Fluids
Density does not = weight!
D = m/V = mass per unit of volume
[density units = kg/cubic meter]
Specific Gravity of a substance = (density of the substance)/(density of water)
spec. grav. = (D of the substance) / (D of water)
so: alcohol has a sp. grav = (0.80 g/cc)/ (1 g/cc) = 0.80
Pressure does not equal force!
P = F/A = force per unit area
[pressure units = N/square meter = Pascals]
P = mg/A
so: P = Dgh where h = the depth of the fluid
How a monometer measures pressure
1 atm = 101,000 Pascals = 14.7 lb/square inch = 760 mm of Hg
so:that's a force of 101,000 N per square meter!!
Absolute Pressure vs. Guage Pressure
Guage Pressure = (Absolute pressure - 1 atm)
so: a flat tire has a guage pressure of zero, but an absolute pressure of 1 atm :-)
Pascal's Principle (and hydraulics)
Pout = Pin
Fout/Aout = Fin / Ain
Bouyant force = wt. of the displaced liquid
(Vol. submerged)/(total V) = (D of object) / (D of liquid)
Equation of continuity
(A)(v) = const.
(A1)(v1) = (A2)(v2)
(see equation 10-5 on page 290)
Applications of Bernoulli's Principle
short bernoulli ppt
Ch. 11 Vibrations and waves
Mass on a Spring
...F = kx or F = -kx
...EPE = (1/2)kx2 or EPE = (avg force)(dist)
...T = 2(pi)(m/k)^0.5
.....max v = A(k/m)^0.5
.....max a = (max F)/m = (kx)/m
Simple Harmonic Motion
...F ~ (-x)
...graphs x, v & a vs. time
...x = Acos(2(pi)t/ T) if x = A at t = 0
.....comparison of SHM with Uniform Circular Motion (motion and equations)
............max v = (2(pi)A)/ T
...T = 2(pi)(L/g)^0.5
....Energy conservation: max PE = max KE to find max v
...frequency of a wave = frequency of the source (for stationary sources)
...the wave Equation: v = (freq)(wavelength)
....reflection at fixed and free end
....reflection and transmission as a wave moves from slow to fast, or fast to slow
.........(note changes in wavelength andwhen the waves flip upside down)
....constructive and destructive wave interference
...Standing wave shapes
...the nth harmonic = (n)(fundamental frequency)
...v = (freq)(wavelength)
........where the wave speed is the same for each harmonic
..............(speed is NOT effected by amplitude or frequency!)
Sound waves are longitudinal waves (compressions and rarefactions)
Speed of sound in solids, liquids, gases (fast, medium, slow)
Speed of sound in air = 343 m/s (approx)
... v = (331 + 0.6T) m/s
Transverse standing waves on strings
...f = v / (w.l.)
...v = (T/(m/l))^0.5
Longitudinal standing waves in columns of air
...O - C column of air produces odd harmonics
...moving listener changes the relative velocity of sound waves: f = v'/(w.l.)
...moving source changes the wavelength of the sound waves: f = v/(w.l.)'
...see textbook for equations!
Ch.11/12 Test Review/Tips:
Ch.11/12 Test - Equations and Tips (pdf)
Ch.11/12 Test- Equations ansd Tips (Word doc)
Ch. 23 Reflection & Refraction
Locate images in a plane mirror by ray tracing
Locate images formed by curved mirrors and lenses by ray tracing
Apply the magnification equation and the mirror equation to curved mirrors
.....M = hi/ho = -di/do .....1/f = 1/di + 1/do
..........Convex (-f), Concave (+f),
.........(-di) for virtual images, (+di) for real images, (-M) for inverted images
.....Index of refraction
......... n = c/v
..........(n)(wl) = (n')(wl')
..........n1sinA1 = n2 sinA2
.....Multiple layer shortcut
Total internal Reflection
....critical angle (only when slow to fast!)
....sinA = (n2/n1)
....Converging (+f) are thicker in the middle, Diverging (-f) are thinner in the middle
....M = hi/ho = -di/do .....1/f = 1/di + 1/do
Ch. 24 The Wave Nature of Light
... (wl') = (n/n')(wl)
... for waves "in phase":
........ if the path difference = 0 wl, 1 wl, 2 wl, ...(m) wl, we get constructive interference
........ if the path difference = 0.5 wl, 1.5 wl, (m + 0.5) wl, we get destructive interference
..............where m = 0,1,2,3,....
Interference pattern for circular water waves
... "nodal lines"
... "changes in the interference pattern when the source separation and/or wavelength changes
Double Slit Interference (Young's Experiment)
.... thin slits produce circular waves
... these circular waves interfere to produce bright and dark "interference fringes"
... constructive interference if path difference = (m) wl (see above)
....... dsinA = (m)(wl) MAXIMA
... destructive interference if path difference = (m + 0.5) wl
........dsinA = (m + 0.5) wl MINIMA
....Given slit separation "d", distance to screen "L", distance between maxima "x"
........tanA = x/L
.............using tanA = sinA (small angle approximation)
.............(m)(wl) = dsinA = dtanA = dx/L
........wavelength of the light = (dx)/L
........To find the distance "x" from centerline mth order minima:
........ bsinA = (m)(wl)
Multiple slit diffraction gratings
........Same as double slit, but the maxima are more discrete
The visible spectrum (ROYGBV)
... Red to Blue: (long wl, low freq) to (short wl, high freq)
....Colors separate due to refraction and different speeds (indexes of refraction)
....Due to dispersion and total internal reflection
Spectrometer and spectroscopy
....prisms and/or diffraction gratings spread light
....emission spectra (bright line spectra) vs. absorption spectra
....elements have "fingerprints"
....red shift and blue shift
Thin film interference
....caused by constructive and/or destructive interference of waves reflected at boundaries
....(careful, sometimes the waves flip upside down when reflection, other times they reflect rightside up)
....see book for equations
Colors on Bubbles and CD's
....colors are due toconstructive and/or destructive interference
....parallel axes => 50% transmission
....perpendicular axes => 0% transmission
....glare from windows and water is usually polarized
.........glare from horizontal surface is polarized horizontally <------->
Ch 23/24 review sheet (pdf)
Ch23/24 test - question types (2006/2007)
1. Ray diagrams and location and characteristics of images
a. Plane Mirror
b. Curved Mirrors
2. Apply the mirror and lens equations to mirrors and lenses
.....1/f = 1/di + 1/do......M = hi/ho = -di/do
3. Refraction: sketch the path of light and apply Snell's Law
..... n1sinA1 = n2 sinA2
4. Critical angle angle and total internal reflection
..... n1sinA1 = n2 sin90
5. Interference of two or more sources
.....double slit and diffraction gratings
6. Single slit interference pattern
7. Conceptual question(s) about
Ch. 16: Electric charge and Electric field
Positive and Negative Charge
Charge is "conserved"
Like charges repel; opposite charges attract
Methods of charging an object
...."friction" (two objects are rubbed together)
...."conduction" (also called "contact")
...."induction" (and grounding)
. F = kqQ/R2 (for point charges)
. where k = 9 x 109 Nm2/C2
. F is a vector
. F ~ 1/R2 (inverse square law!)
. E = F/q (anytime!)
. E = kQ/R2 (for point charges)
. E is a vector
. by convention, E points toward a negative charge and away from a positive charge
Problems involving 2 or more point charges (see Ch.16 HW)
. Find F on a particle (by adding vectors)
. Find E near charged particles (by adding vectors)
Electric field inside a conductor
. Charge in or on the conductor will move until E = 0
Charged rod and pith ball
Charging an Electroscope
Electric field and equipotentials
Electric field around two charges
Charging by friction
Charge theft - why a VDG loses charge
Ch. 17 Electric Potential, Electric Potential Energy, Capacitors
Work = Fd (sort of)
Work = change in energy
Electric Potential = "voltage" = (Electric Potential Energy)/(q)
. = Joules per Coulumb = volts
Work, energy and electric potential are scalars (easy math)
For Uniform electric field (like between parallel charged plates):
. W = change in EPE
. W = Fd = (qE)d
For Parallel Plate capacitors
. W/q = Ed
. so E = V/d
. C = Q/V
. where C = capacitance, not coulombs
. C = (epsilon-sub-zero)(A)/d
. where epsilon-sub-zero = 8.85 x 10-12 F/m
. Stored Energy = (1/2)QV = (1/2)CV2
For point charges (if we set EPE = 0 when R = infinity):
. EPE = kQq/R
. V = kQ/R
Breakdown of air occurs when E = 3 x 106 V/m
Note the units of Electric Field: N/C = V/m
Factors affecting capacitance
Electric field and voltage
I = q/t = charge passing each second = coulombs per second = amperes
V = EPE/q = electrical energy per coulomb = Joules per coulomb = volts
I = V/R
............ I ~ V
............ I ~ 1/R
R = (resistivity)L/A
............R ~ L
............R ~ 1/A
..................note: A = 2(pi)r2 so R ~ r2
P = E/t = IV = J/s = watt
E = (P)(t)
E = (J/s)(s) = J
E = (kW)(hrs) = kWh
Joules or kWh
1 kWh = 3,600,000 J
The Ohm Zone (quite good, but the applet does make occasional errors)
Ch. 19 DC Circuits
Series vs. Parallel Circuits
...all electrons follow the same path
...Total resistance increases as more resistors are added in series.
......Total R = R1 + R2 + ...
...the current is the same for each component (ie: battery, bulbs or resistors)
...the battery's voltage is divided among the components (ie: bulbs or resistors)
......voltage drop is proportional to the resistance (bulbs with higher resistance have higher voltage drop)
...remove one bulb and they all go out
...electrons have a choice of paths
...Total resistance decreases as more resistors are added in parallel
......1/Rtotal = 1/R1 + 1/R2 + ...
...the voltage is the same for each component
...the battery's current is divided among the components
......current is inversely proportional to the resistance (bulbs with higher resistance have less current)
...remove one bulb and the others stay lit
... determine the current and voltage drop for each component in a circuit
... fuses and circuit breakers
...1/Ctotal = 1/C1 + 1/C2+ 1/C3 +.....
... Q1 = Q2 = Q3 = ...
... V = Q/C
...Ctotal = C1+ C2 + C3 +...
...Qtotal = Q1+Q2 + Q3 +...
...V = Q/C
Capacitor RC time constant
The Ohm Zone (quite good, but the applet does make occasional errors)
Ch18/19 practice (sorry, the best I could do with the little time I had)
ch.18/19 practice (no solutions yet)
Ch. 21 Electromagnetic Induction and Faraday's Law
Most important Magnetic Induction topics for the AP Physics B exam:
1. A changing magnetic field near a coil induces a voltage in the coil (Farady's Law).
.....EMF~number of turns
2. A voltage will be established (and current will flow) in a coil that opposes the change in flux (Lenz's Law).
3. What is magnetic flux? (Calculate magnetic flux)
....Magnetic flux = BAsin(theta)
4. Apply Faraday's Law
....EMF = -N(change in flux/time)
5. Motional EMF
....EMF = BLv
....which end of a rod moving in an external magnetic field has higher voltage? (RHR: F=qvB)
....calculate emf and force for a rod moving in an external magnetic field has higher voltage (RHR: F=ILBsin(theta))
....(P)in = (P)out
....(IV)in = (IV)out
....(N2/N1) = (V2/V1) = (I1/I2)
7. Why is power sent at high voltage in transmission lines?
8. How does a generator work? (compare and contrast to a motor)
(ppt from lecture on request)
1. Physics Facts
List of 100+ basic physics concepts you are expected to know for the AP Exam in May.
2. Start reviewing the equations listed in the equation tables!
....College Board website for AP PhysicsB
....2007 Equation tables for the B and C exams
....Past free response questions AND solutions
....Review for the AP Exam (suggestions and links)
3. Click here: AP exam review
Recognizing Forces (EXCELLENT PRACTICE) Test your ability to identify ALL forces acting on an object!
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