Khan Academy for Prelim and HSC Physics

The Khan Academy is an online educational resource with short (up to 10 minute) lectures on different topics. Below are the Khan Academy videos relevant to Preliminary & HSC Physics.

So - if you didn't quite get something in the last two years and you want it explained again,
Or - if you want some extra worked examples for numerical calculations
Or - you want to hear things explained in a new way,

I recommend you watch the videos below.

But please, no matter how well-intentioned, please don't say "Thanks, I never understood xxxxx before - but now I do thanks to those videos" - even though I will be really happy for you, my professional pride will be wounded.

THE WORLD COMMUNICATES

1. Introduction to Waves
2. Amplitude, Period, Frequency and Wavelength of Periodic Waves
3. Introduction to the Doppler Effect
4. Specular and Diffuse Reflection
5. Specular and Diffuse Reflection 2
6. Refraction and Snell's Law
7. Refraction in Water
8. Snell's Law Examples 1
9. Snell's Law Example 2
10. Total Internal Reflection

ELECTRICAL ENERGY IN THE HOME

11. Electrostatics (part 1): Introduction to Charge and Coulomb's Law
12. Electrostatics (part 2)
13. Electric Potential Energy
14. Voltage
15. Circuits (part 1)
16. Circuits (part 2)
17. Circuits (part 3)
18. Circuits (part 4)
19. Introduction to Magnetism

MOVING ABOUT

20. Introduction to Vectors and Scalars
21. Calculating Average Velocity or Speed
22. Solving for Time
23. Displacement from Time and Velocity Example
24. Acceleration
25. Newton's First Law of Motion
26. Newton's Second Law of Motion
27. Newton's Third Law of Motion
28. Airbus A380 Take-off Time
29. Airbus A380 Take-off Distance
30. Why Distance is Area under Velocity-Time Line
31. Average Velocity for Constant Acceleration
32. Acceleration of Aircraft Carrier Takeoff
33. Race Cars with Constant Speed Around Curve
34. Deriving Displacement as a Function of Time, Acceleration and Initial Velocity
35. Visualizing Vectors in 2 Dimensions
36. Normal Force and Contact Force
37. Normal Force in an Elevator
38. Inclined Plane Force Components
39. Ice Accelerating Down an Incline
40. Force of Friction Keeping the Block Stationary
41. Correction to Force of Friction Keeping the Block Stationary
42. Force of Friction Keeping Velocity Constant
43. Introduction to Momentum
44. Momentum: Ice skater throws a ball
45. 2-dimensional momentum problem
46. 2-dimensional momentum problem (part 2)
47. Introduction to work and energy
48. Work and Energy (part 2)
49. Conservation of Energy
50. Work/Energy problem with Friction

COSMIC ENGINE

1. Scale of Earth and Sun
2. Scale of Solar System
3. Scale of Distance to Closest Stars
4. Scale of the Galaxy
5. Intergalactic Scale
6. Hubble Image of Galaxies
7. Big Bang Introduction
8. Radius of Observable Universe
9. (Correction) Radius of Observable Universe
10. Red Shift
11. Cosmic Background Radiation
12. Cosmic Background Radiation 2
13. Cosmological Time Scale 1
14. Cosmological Time Scale 2
15. Birth of Stars
16. Becoming a Red Giant
17. White and Black Dwarfs
18. Hubble's Law
19. Lifecycle of Massive Stars
20. Supernova (Supernovae)
21. Supernova clarification
22. Black Holes

SPACE

51. Introduction to Gravity
52. Mass and Weight Clarification
53. Viewing g as the value of Earth's Gravitational Field Near the
54. Gravity for Astronauts in Orbit
55. Would a Brick or Feather Fall Faster
56. Normal Force and Contact Force
57. Normal Force in an Elevator
58. Plotting Projectile Displacement, Acceleration, and Velocity
59. Projectile Height Given Time
60. Deriving Max Projectile Displacement Given Time
61. Impact Velocity From Given Height
62. Visualizing Vectors in 2 Dimensions
63. Projectile at an Angle
64. Different Way to Determine Time in Air
65. Launching and Landing on Different Elevations
66. Total Displacement for Projectile
67. Total Final Velocity for Projectile
68. Correction to Total Final Velocity for Projectile
69. Centripetal Force and Acceleration Intuition
70. Visual Understanding of Centripetal Acceleration Formula
71. Loop De Loop Question
72. Loop De Loop Answer part 1
73. Loop De Loop Answer part 2
74. Acceleration Due to Gravity at the Space Station
75. Space Station Speed in Orbit
76. Introduction to Newton's Law of Gravitation
77. Gravitation (part 2)

MOTORS & GENERATORS

78. Introduction to Torque
79. Moments
80. Magnetism 2
81. Magnetism 3
82. Magnetism 4
83. Magnetism 5
84. Magnetism 6: Magnetic field due to current
85. Magnetism 7
86. Magnetism 8
87. Magnetism 9: Electric Motors
88. Magnetism 10: Electric Motors
89. Magnetism 11: Electric Motors
90. Magnetism 12: Induced Current in a Wire
91. Introduction to Magnetism

IDEAS TO IMPEMENTATION

92. Magnetism 2
93. Magnetism 3
94. Magnetism 4
95. Magnetism 5

QUANTA TO QUARKS

96. Four Fundamental Forces
97. Types of Decay
98. Half-Life

Khan Academy for Prelim and HSC Chemistry

The Khan Academy is an online educational resource with short (up to 10 minute) lectures on different topics. Below are the Khan Academy videos relevant to Preliminary & HSC Chemistry.

So - if you didn't quite get something in the last two years   and you want it explained again,
Or - if you want some extra worked examples for moles (see the Metals unit),
Or - you want to hear things explained in a new way,

I recommend you watch the videos below.

But please, no matter how well-intentioned, please don't say "Thanks, I never understood xxxxx before - but now I do thanks to those videos" - even though I will be really happy for you, my professional pride will be wounded.

THE CHEMICAL EARTH

1. Elements and Atoms
2. Introduction to the atom
3. Orbitals
4. More on orbitals and electron configuration
5. Electron Configurations
6. Electron Configurations 2
7. Valence Electrons
8. States of Matter
9. States of Matter Follow-Up
10. Covalent Networks, Metallic, and Ionic Crystals

METALS

11. Groups of the Periodic Table
12. Periodic Table Trends: Ionization Energy
13. Other Periodic Table Trends
14. Ionic, Covalent, and Metallic Bonds
15. Molecular and Empirical Formulas
16. The Mole and Avogadro's Number
17. Formula from Mass Composition
18. Another mass composition problem
19. Balancing Chemical Equations
20. Stoichiometry
21. Stoichiometry: Limiting Reagent
22. Stoichiometry Example Problem 1
23. Stoichiometry Example Problem 2
24. Limiting Reactant Example Problem 1
25. Empirical and Molecular Formulas from Stoichiometry
26. Example of Finding Reactant Empirical Formula
27. Molecular and Empirical Forumlas from Percent Composition

WATER

28. Stoichiometry of a Reaction in Solution
29. Another Stoichiometry Example in a Solution
30. Van Der Waals Forces
31. Solubility
32. Boiling Point Elevation and Freezing Point Supression

ENERGY

33. Introduction to Kinetics
34. Reactions in Equilibrium
35. Enthalpy
36. Heat of Formation
37. Hess's Law and Reaction Enthalpy Change

PRODUCTION OF MATERIALS

38. Enthalpy
39. Introduction to Oxidation States
40. More on Oxidation States
41. Redox Reactions
42. Galvanic Cells
43. Types of Decay
44. Half-Life

THE ACIDIC ENVIRONMENT

45. Le Chatelier's Principle
46. Introduction to pH, pOH, and pKw
47. Acid Base Introduction
48. pH, pOH of Strong Acids and Bases
49. pH of a Weak Acid
50. pH of a Weak Base
51. Conjugate Acids and Bases
52. Buffers and Hendersen-Hasselbalch
53. Acid Base Titration
54. Strong Acid Titration
55. Weak Acid Titration
56. Titration Roundup

CHEMICAL MONITORING AND MANAGEMENT

57. Spectrophotometry Introduction
58. Spectrophotometry Example
59. Introduction to Kinetics
60. Reactions in Equilibrium
61. Le Chatelier's Principle

Einstein and Planck stuff

Every year I get to this dot point (which by then I have forgotten) and the cogs of my brain start turning again and I eventually have some new revelations

This year I'm thinking on these lines:

1) Planck - was science research removed from society? – NO. Science should serve the society of ones nation (nationalist) -  in his case Germany (which in war time meant supporting the German war effort).

2) Planck - was Science research removed from politics? – NO. Sscience research should be dictated by political powers to direct the research to serve the nation - the ultimate decision/responsibility about the uses/consequences of the research lay with the political powers.

3) Einstein - was science removed from society? – NO. Science should serve the entirety of humanity - not any particular nation. Scientists had a responsibility to society and had to take responsibility for the consequences of their research.

4) Einstein - was Science research removed from politics? – NO. Scientists had a role in shaping politics and society - they should use their research and findings to sway political and public opinion to better serve all humankind.

Now if I was writing an essay on this I would need to detail what they did in WWI and WWII and provide evidence (in what they did) to support each of my 4 proposals. Which I think I could do.

BUT you might completely disagree with these 4 ideas - THAT IS OK - you can make any claim you like about 'whether science research is removed from social and political forces' - as long as you can construct an argument to support your claim.

Don’t forget to read the semiconductor article here

Ahem - despite arguments to the contrary my official title is:
Primo Brick, Round Rattle 1 x 1 with Blue Overalls and Animal Face Pattern

Physics Animations

Here are some Physics applets to play with to prepare for Ideas to Implementation and Quanta to Quarks.

They are presented in chronological order for the course:

IDEAS TO IMPLEMENTATION

1) Revise what an EM wave is here

2) Learn about standing waves - important for Hertz's experiment -  here

3) Learn about blackbody radition by clicking the image below:

Click to Run

4) To learn about the photoelectric effect click here and/or on the image below:

Click to Run

5) Learn more about wave interference here and/or by clicking on the image below:

Click to Run

QUANTA TO QUARKS

1) Learn about Rutherfords alpha scatteirng experiment by clicking on the image below:

Click to Run

2) Learn about Bohr's model of hydrogen by clicking here

3) Learn about further models of hydrogen by clicking the image below:

Click to Run

4) Learn about the Davisson-Germer experiment by clicking the image below:

Click to Run

5) Learn about alpha decay by clicking the image below:

Click to Run

6) Learn about beta decay by clicking the image below:

Click to Run

7) Learn about nuclear fission by clicking the image below:

Click to Run

On the topic of physics animations and games - Minecraft is amazingly cool retro-feel game. I wrote it off as garbage on first appearance but about 100 hours later - I can verify that it is fun and addictive.

What a feeling to be tunnelling deep into the Earth, carefully making my way past a lava pool, and finding my first diamond ore. It was right up there with defeating my first Enderman, getting my first Blaze Rod and killing a Ghast with its own fireball...

They are even making Minecraft LEGO!!!

On the topic of awesome games - a new level of Kingdom Rush has JUST been released on iTunes!

Changing Pressure in a Discharge Tube

See the video below - interesting:









And what has this strange little gnome got to do with HSC Physics?

Click here to find out!



Motors & Generators Assessment - Notes Feedback

Hi - I've just finished checking and correcting (not marking) the notes you submitted for Part 2A. WOW - some very good ideas and a lot of hard work went into those notes. You should be proud. However, there were some frequent areas to improve and a few misconceptions. Your notes will be annotated to show which of these relate to you:

ai)
(A) For all diagram of motors make sure you show the current flow in the coil and the correct direction of torque produced by the motor effect.

aii)
(B) Make sure you say that because the current flows in opposite directions on either side of the coil the motor effect is in opposite directions on either side via the LHR, thus resulting in a torque about the axis.

(C)  You need to relate the torque to the equation t = nBIAcosq and should note that momentum carries the coil past 90 degrees.

aiii)
(D) Increased magnetic field strength can be achieved by increasing the stator magnet strength AND by using a laminated soft iron core. Also - don't say move the magnets closer together - moving them closer to the coil may work (but not as important as the other two mentioned) but suggests that you are going to decrease the size of the coil - which would actually decrease torque.

(E) To increase the current you can decrease the resistance of the coil or increase the supply voltage.
NB in a resistor (any device that cases a voltage drop because electrical energy is being converted to heat, kinetic, light, etc) Ohm's Law applies ie I = V/R. Thus increasing the voltage drop (potential difference) = increased current flow. A transformer is different - it is close to 100% efficient and electrical energy is both input and output - there is no transformation of energy, so the electrical power in must equal the power out VpIp =VsIs thus increasing the secondary voltage causes the secondary current to decrease.

aiv)
(F) Laminations are thin layers of soft iron separated by ferrite (an iron oxide). The ferrite is an insulator but is ferromagnetic so it still enhances the magnetic field strength. The laminations run perpendicular to the COIL. They cannot run perpendicular to the field as they are rotating in the field with the rotor.

av)
(G) You MUST refer to the LHR when talking about a speaker. You must explicitly say that changing the direction of the current changes the direction of the motor effect force and thus AC causes the cone to move in and out - producing a sound wave.

(H) See (B) above and make sure you explain the production of the torque if asked a question about galvanometers.

(I) The radial magnets make the coil always at zero degrees to the field. THUS torque is INDEPENDENT of angle and only PROPORTIONAL TO CURRENT. Thus a LINEAR SCALE can be used to measure the current.

bi)
(J) When drawing generators always show the applied torque and the direction of induced current (and make sure you get it right!)

bii)
(K) The rotating coil in a generator causes an AC emf to be induced in the generator as the direction of flux in the coil is constantly changing as it rotates. The induced emf changes diction when the coil is at 90 degrees to the field. This is when the split ring commutator changes the brush connection so the output current is alwayss in one direction

biii)
(T) Generators work on the principle of induction  - thus you must refer to Faraday's law when discussing how to improve them - everything that increases the induced emf ( and thus the induced current) is based on increasing the flux change or decreasing the time over which the flux change occurs. Laminated iron cores and stronger magnets, and more turns and bigger areas increase flux change. Spinning the generator faster increases the rate of change

biv)
(L) When comparing DC motors and generators you MUST talk about the supply of current (motor) vs the supply of torque (generator). You need to talk about the input vs output energy for both. You must talk about the role of the split ring commutator in either changing the input DC to AC in the coil (for a motor so the torque is in constant direction) OR the coil AC to output DC (in a generator). Finally, you MUST say that motors use the motor effect and generators use Faraday and Lenz's Laws.

bv)
(M) You must explain why there is an AC induced in the coil of a DC generator - see (K) above. Drawing the graphs of flux, rate of flux change, -rate of flux change are great for explaining this as you refer to them. Ie "Faraday's Law and Lenz's Law  says the induced emf opposes the flux change  - thus an AC emf is induced as shown by the graphs..."

ci)
See (J) above

ciii)
(N) BE CAREFUL. Unless you are an Autobot or Deceptacon AC generators are never 'easily transformed'. What you MUST say is that "The AC PRODUCED by an AC Generator is easily transformed...". Also be aware that the Q asked you to compare the pros and cons of the generator. Transformation is one advantage of AC power (and thus generators) but don't neglect the actual pros and cons of the generator structure - ie DC split rings wear  & spark etc.

civ)
(O) Apart from the operational details the other things that you can/should compare between an induction cooker, EM brake and AC generator are:
The source of the flux change (ie AC coil vs motion between conductor and field)
The physics principles in place - all use Faraday's Law and Lenz's Law but EM brakes also use the motor effect and induction cookers also use resistance heating.

cv)
(P) You must be able to explain exactly what Westinghouse did to win. He undercut Edison's bid to power the CHICAGO World Fair - thus showing the success of his system to a global market. he was able to harness hydroelectricity from Niagara and transmit is over 20km away to Buffalo - all because AC was more efficient and ie it could be transformed and sent with low power loss unlike DC.

cvi)
(Q) You must be able to detail the STEP UP voltages at the power station and then each STEP DOWN transformations (and voltages) to the household THEN give at least one example of step up and step down in the household.

cvii)
(R) Don't forget that 'assess' means positives, negatives and JUDGEMENT. It is critical that you examine the effect of CO2 on global environment and that you have at least ONE VERY developed argument (for the top marks they base it on your longest chain of argument ie Fossil fuel burned = CO2 = enhanced greenhouse effect = global warming = sea level rise = loss of habitats = disruptions of ecosystems and displaced people. You MUST provide a judgement - it would be difficult to argue that AC generators have been positive for the environment (society yes, environment no).

cviii)
(S) Many were missing a critical link. Most linked transformers to transmission of power over long distances and thus ready access to electricity and electrical appliances BUT then when it cane to categories like medicine, business etc the link as gone. You can't just say transformers have been 'good' for medical diagnosis. You need to say that "electrically powered medical diagnostic & treatment devices have increased health of society..."

Please don't assume that because these comments are long that the answers were poor. Quite the contrary - they were deep and broad so that a number of issues came to light. Overall the Physics you communicated was fantastic.

BTW - very soon these awesome pics will make sense:

Symbols, Biopolymers and Study

Chem study notes (with an extra page of advice), my ridiculously long essay on PHB and one of my 'best ever' students essays on 922* can be found at this link. *NB The essay question they had to do required them to basically summarise the key concepts from the whole 9.2.2 focus area into one 2-page essay. For your own study, you should be able to convert this to a ~1pg essay focusing on PHB (Biopol) only.

When typing up stuff for Physics and Chemistry don't be afraid to use symbols. If you don't like using the INSERT SYMBOL buttons just type the appropriate letter from the table below and change the font to 'symbol' font.

And if you haven't played it yet - don't start playing till you have finished your assessments - but THEN enjoy these:

GROW Cube

GROW RPG

GROW (original)

GROW Island (favourite - can you find the secret ending...)

GROW Valley

Advice for 2012 (AKA - Late Night Rant)

I’ve just marked some Physics tonight and I cannot sleep

Why?

Well, the best way to answer is to revive something I posted to my previous students:

All my many years of thinking about how to best-prepare for the HSC has been condensed and crystallised into the (awesome & multilayered) diagram below. 

So,

*Before you ask about how you are going, or before you next submit a draft, homework task, experiment report or study notes, take time to ponder its’ mysteries. 

*Before you even think of handing me anything, ask yourself “Should I hand in anything that is below my absolute best?” ...

  

& also my dear Physicists:

Knowledge is power

A razor sharp sword

 But how will you wield THE SWORD?

There is a saying that a little bit of knowledge is a dangerous thing

  

How will you wield THE SWORD?

Will you clumsily and carelessly ignore what you have learned?

  

Will you fall on THE SWORD?

Or will you wield THE SWORD masterfully to smite your foes?

Will you wield THE SWORD to kick butt in the HSC like I know you can?

In Physics what is THE SWORD?

Or more correctly:

What is DE SAUD?

Data/Diagram

Equation

Substitution

Answer

Units

Direction

Omitting any of these is a serious Physics:

It is simple.

It is powerful.

It should be an easy decision.

But it is YOUR choice

FIRE UP!

Rant over

New Year, New School, New Students

To my new Physics and Chemistry students: 
Welcome to the Dr Blurg blog!

This will be updated throughout the year with links, activities, notes, assessment information and all sorts of random science-related stuff I stumble across throughout the year.

If I uplooad something ctitical for your study I will notify you via email.

For now here are the most important links for the year:

Chemistry Syllabus

Chemistry Data Sheet & Periodic Table

Chemistry Multiple Choice Online

Chemistry - HSC Online

EasyChem (a good study resource)

Chemistry & Physics Past HSC Exams

Physics Syllabus

Physics Data & Formula Sheets

Physics Multiple Choice Online

Physics - HSC Online

HSC 2011

CLICK HERE FOR ACCOMPANYING SOUND EFFECTS