External Knowledge Training
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Physics - Introductory Berkeley course
- All notes by John Eagles
1 Introduction
Today i started watching this introductory course in physics. It's a UC Berkeley course given by Richard Muller. He explains physics without using many equations. In this particular lecture he comments quite a bit on 9/11 related physics and dwells on terrorist shoe bombs. He advises the government in such matters, so his views seem a bit politically colored. But he really knows how to present laws of physics in a very understandable and close-to-life manner. I've learned quite some new things from watching this lecture.
2 Solar technology, coal reserves
Summary of topics lectured about:
- Calories of food
- Peripheral vision of the eyes detect especially motion
- Solar technology
- Tilt of the earth & the seasons
- Global warming in relation to the forming of clouds. When the climate heats up, more clouds may form and may counter the greenhouse effect.
- Canada is 2nd in the world after Saudi Arabia for its oil reserves, but Canada has it stored in oil sand and it's more expensive
- Natural gas & shale gas in comparison to oil
- Coal reserves: The USA has most reserves, then comes Russia and then China, Australia and India. These reserves are big in terms of energy compared to the world's oil reserves.
- Coal and methane can turned into gasoline, but it's still risky in case the oil prices are lowered.
- In politics, there's conflict between the issues of global warming and energy security.
- Coal is the cheapest form of energy.
- IPCC errors
- Sequestering CO2 and making clean use of coal
- CCS = Carbon Capture & Storage
3 Temperature scales
Topics in this video:
- Size of atoms
- Density of atoms
- What makes atoms move, what gives them the kinetic energy?
- Temperature = how much energy do things have
- Thermometers
- Scales of Celcius, Fahrenheit
- Liquid nitrogen experiments
- There are ca 1000 x more molecules in a fluid than in a gas of the same substance per volume
- Temperature of absolute zero on the Kelvin scale means there is no energy
- In the Kelvin scale the amount of energy is proportional to the temperature
- A fire extinguisher has liquid CO2
- Your subjective temperature measurement
- Hot air rises because it's less dense
- Conduction, convection, radiation
Lecturer is Bob Jacobsen
4 Thermodynamics intro
- The ideal gas law (relationship between volume & temperature)
- Movements of small and bigger molecules and atoms
- Energy efficiency of engines
- Refrigerators
- Air conditioners
- Entropy = a measure of disorder
5 Satellites, gravity
This lecture is about:
- Friction
- Movements of satellites
- Why frisbees and airplane wings lift
- Satellites move with 5 miles per second. They are falling but because the earth is curved, they fall with the earth curve
- Rockets escape velocity
- Gravity force between two people near to each other is ca mass of a mosquito
- What does it mean to be weightless
- How do spy satellites work. They have to be close to the ground. It takes them 1 1/2 hour to orbit the earth one time.
- Unmanned drones
- Weather and tv satellites orbit the equator at 22000 miles high and need 24 hours for one cycle: Geostationary satellites
- 24 GPS satellites go around in 12 hours.
6 Newton's laws, inertia, circular motion
Topics explained in this lecture, illustrated with several experiments:
- Newton's laws
- Inertia
- Circular motion
7 Radiation, radioactivity
- Ionizing radiation knocks electrons off atoms.
- We're exposed to some amount of ionizing radiation all the time.
- Tritium is used in some watches.
- Damaging of DNA is what causes cancer.
- Sieverts - Grays - rems.
- 2500 rems (25 Sieverts) on average causes 1 fatal cancer. It's a probability.
- Radiation illness - requires much less than a dose causing cancer.
- About percentages of increase of cancer because of radioactivity.
- Alpha rays don't penetrate deeply, are stopped by the skin.
- X-rays.
8 Global warming, radioactive rays, radiocarbon dating
- Categories of believers and non-believers in global warming.
- Errors in IPCC reports
- He quotes research stating that organic food is unhealthy?!?
- Chemotherapy & radiation therapy against cancer, how does it work?
- The energy release of exploding a nucleus is typically 1 million times more than energy released in chemical reactions.
- In the early universe almost all atoms probably were explosive or radioactive.
- Radiocarbon dating with C14, having a half-life time of 6,000 years. C14 is in the atmosphere because of cosmic radiation affecting C atoms. Living organisms take in a percentage of these C14 atoms. The amount of C14 in the atmosphere is constant.
- Potassium-Argon dating: A dating method using rocks.
- Beta rays are fast electrons.
- Alpha rays consist of small nuclei of 2 protons and 2 neutrons that form He atoms when the rays are stopped.
- Gamma rays are penetrating, not ionizing colliding particles. They pass through things. They knock off electrons and are very energetic.
- X rays are the same as gamma rays but more energetic. X-ray photos create shadows.
9 Nuclear reactors, uranium, chain reactions
This lecture is about:
- How to get useful energy from radioactive elements.
- Chain reactions and nuclear fission.
- U235 is more radioactive than U238, but there's much less of U235 on earth (U = uranium).
- Enrichment of uranium is removing what you don't want, for example by using centrifuges.
- Depleted uranium.
- Natural and oldest man-made nuclear reactors.
- The nature of chain reactions.
10 Nuclear waste, fusion reactors
- Where to store nuclear waste?
- Safety measures for nuclear plants.
- Spent fuel rods and spent fuel storage installations.
- Nuclear waste transport.
- Waste from uranium mines.
- Fusion reactors are still not commercially operated.
11 Graphene, electricity basics
- Four different carbon bonds.
- Graphite and graphene. Graphene is a newly produced one-layer sheet of graphite.
- Sparks from static electricity.
- Voltage, currents, resistance.
- Fuses and circuit breakers.
- Electrocution.
- Fibrillation of the heart.
- AC and DC currents.
12 Magnetism
- What is magnetism?
- Rare-earth magnets have transformed society.
- Rare-earth minerals.
- The earth is a magnet.
- Magnetism comes about when there is a moving charge.
- Magnetic recording, hard disks, credit cards.
- Electric generators = moving wires pass a magnet.
- Transformers.
- Voltage is energy per electron.
- Magnetic levitation.
13 Scientific implications of magnetism - Electrical power
- Power = voltage x current.
- A moving magnetic field makes voltage and provided there is a conductor, a current.
- Alternating currents and direct currents (AC and DC).
- Edison's first promoting of his electric bulbs.
- High-voltage wires.
- Smart grids.
14 Waves
- Seismographs measure the shaking of the ground.
- Atoms are basically a kind of waves, quantum waves.
- A particle is a wave.
- When you shake the vacuum it becomes a wave.
- A wave is moving energy.
- The old concept of 'aether' is now renamed 'vacuum.'
- Different types of waves.
- Earthquakes & tsunamis.
There's a funny interruption of the lecture because of student demonstrations.
15 More about waves
- Waves have three characteristics:
- Amplitude (height or size)
- Energy (intensity or power)
- Speed (small and big waves travel at the same speed)
- Strings of music instruments.
- Piano tuning.
- Interference of sound waves.
- Sound waves.
- Interference of FM radio waves.
- Mirages.