Phy lecture and in the news questions ch 7-13
Although a tsunami travels over the open ocean at hundreds of miles an hour, if you figure out that one is heading to the beach where you are sun bathing, you can out run it. Why is this.
The wave travels fast, but the wavelength is many miles and period is several minutes. It takes a few minutes for the water level to rise.
spectral lines
The wavelengths where a specific element can absorb or emit light
Since the late 1800s, when scientists say that the global average (averaged over night and day, the seasons, and the Earth's surface) temperature was about 56 F, how much has the global average temperature increased?
about 1-2 F
Lasers create a chain reaction or photon avalanche. Their properties?
all go exactly same speed, same direction, and same frequency
A positron is
an electron's anti-particle.
. He used to point sources of waves, and the waves traveled outward in circles around each point source. It looked as if the waves traveled right through each other, but they made a funny pattern. That pattern is very important to understand many wave phenomena. What is the name of that pattern and phenomenon?
an interference pattern.
Dr. Muller, the author of your textbook says that some people who write or talk about the changing climate
are exaggerating the dangers tho it is a real and serious threat
Diamonds sparkle in many colors when illuminated by white light because
different colors travel at different speeds inside diamonds.
Properties of waves
diffract, refract, reflect, and interfere. They also bend around obstacles
what is the wavelength
distance between crests
Ch 7
fml
The energy of a photon depends on its
frequency (color for visible light).
If you double the absolute temperature (K) of something, the wavelength of the emitted blackbody radiation
gets shorter by 2
In the Einstein equation, E = hf, E stands for energy and f stands for frequency. what's h
h is Plank's constant
Approximately what is the wavelength of visible light?
half a micrometer
ch 8
help
How old was einstein when he came up with his equation
in his 20s in 1905
Rainbows show different colors because
in water, different frequencies have different velocities
Thanks to human activity, burning fossil fuels, carbon dioxide in the atmosphere has
increased ~36%
All objects emit electromagnetic radiation with a wide spectrum, lots of different frequencies. For things that are at room temperature, 300 K or say 70 F, what is the name for the frequency range that they emit?
infrared
Most of the energy of an ordinary incandescent, tungsten-filament lightbulb is emitted in the color
infrared
ch 11
lego
Ch 7
lets gooo
Does infrared light have a longer wavelength or a shorter wavelength than visible light?
longer
Cell phones emit
microwaves
forms of electromagnetic radiation
microwaves, gamma waves, visible light. Alpha and beta rays are NOT
Pepper's Ghost illusion tricks our eyes and minds by using
mirrors
Dr. Leikind's mass is about 90 kg. (About 195 pounds in ordinary speech.) If he were zooming through the classroom moving close to the speed of light he would appear
more massive to you
The Doppler shift (a change of the color of glowing stuff's spectrum) of the light from distant galaxies is
mostly a red shift. (longer wavelength)
CH 9
noooo
ch 9
oh lawd
ch 8
okayyy
Quantum physics teaches us that even though light shows many effects, such as interference, that demonstrate its wave-like properties, it is also a particle, transferring energy in chunks. What is the name for the particles of light?
photons
ch 11
poop
ch 10
pray
How do we know what is true
reason, authority, revelation, senses
Ch 12
so close baby
CH 10
someone pls hold me
Dr. Leikind's hearing problem is
that he doesn't hear higher tones as well as he used to.
A light-year is
the distance light waves or photons travel in one (Earth) year.
Looking out to great distances, astronomers see many galaxies. Their observations of these galaxies, summarized in Hubble's Law, show that
the farther away they are from us, the faster they are moving away from us. V=HR R=distance from us, H= Hub's constant
What is the quantum effect that Xerox machines use?
the photoelectric effect
Dr. Leikind and other old people need reading glasses because
their eyes' lenses have become too stiff to focus properly for reading.
If we trap (the wave)
then their WL has to fit space they are trapped in
In the Big Bang Theory
there is no center of the Universe.
According to the text moving clocks run slowly, moving objects shrink, and many other odd effects. Why don't we see these effects on the U of Tampa campus or while driving to school or back home?
they are only apparent when things move, relative to each other, at speeds approaching the speed of light.
Large telescopes, used by professionals, are powerful mostly because
they have big mirrors (large diameter) to collect lots of light.
What are the spikes in the pictures of stars in space?
they look like they do because of diffraction with the telescope and such.
When astronomers look at a galaxy that is 5 billion light years away,
they see it as it was 5 billion years ago.
Bats navigate in caves or outside at night using
ultra sound
Radiation from the Sun causes sun tans and sun burns. What part of the Sun's electromagnetic spectrum does this
ultra violet
A black light emits mostly
ultraviolet light
ch 13
wtf
What is the rest mass of a photon? A photon is a particle of light.
zero
Try to put these forms of electromagnetic radiation in order from the highest frequency (or shortest wavelength) to the lowest frequency (or longest wavelength): X-rays, infrared light, microwaves, AM radio, visible light, ultraviolet light, TV and FM radio, γ (gamma) rays.
γ (gamma) rays , X-rays, ultraviolet light, visible light, infrared light, microwaves, FM radio and TV, AM radio
I showed you some photographs of an ancient man that people found in a peat bog in Northern Europe. The well-preserved body had been in the peat for a long time before it was discovered. Roughly speaking, how long?
2000 yrs The bodies were put into the bogs (or fell in). One of them has been dated to about 400 BCE.
People call parts of the San Francisco Bay area around Palo Alto and San Jose, Silicon Valley. Why do they do that?
Computer chips with all the circuits are (mostly) made from silicon, and there are a lot of computer related companies there.
Why does a pinhole camera make an upside-down image?
Each point on the object emits light that passes through the pinhole traveling in a straight line. So high spots on the object end up low in the image
Waves may bend as they travel, following curved paths through whatever they are traveling it. Examples are sound shadows, mirages, sound channels in the ocean. Why do they do that?
If the waving stuff's properties vary, the wave's properties will vary, and the wave will tend to bend in the direction of slower movement.
Tell me your ideas about what a quantum jump or a quantum leap are.
In the microscopic world, things exist in specific energy states, and cannot exist in between. These energy states differ by tiny amounts, and the microscopic things can only absorb or emit energy to go from one distinct state to another.
The increasing carbon dioxide in the atmosphere is warming the Earth. Where is most of the additional heat energy ending up?
In the oceans.
Incandescent light bulbs provide white visible light for us. But most of the energy they radiate is in a different region of the spectrum. What region is that?
Infrared
Some night surveillance cameras and military night vision equipment detect
Infrared light that all objects emit because they are, more or less, blackbodies.
To understand items in the news about North Korean nuclear tests or about the Iranian nuclear deal or even the sinkhole near Lakeland, you have to know about things such as Xe133, U235, and K40. What's the word for these kinds of things?
Isotopes.
Before 1900 the carbon dioxide concentration in the atmosphere had been about 280 ppm (parts per million). Today the concentration is a little above 400 ppm. What does this change about the energy balance of the Earth?
It increases the absorption of the Earth's infrared radiation going upward toward outer space.
In stimulated emission, a photon hits an atom that is in an excited energy state. If the incoming photon has just the right energy, the atom will jump to the lower energy level and two photons will zoom away from the atom. Energy is conserved because the new photon has the energy lost by the atom. One photon came in, say from the left. Two go out to the right. What will happen to the atom?
It will jump backward, to the left, as the new photon goes to the right. This is conservation of momentum.
Astronomers and physicists measure electromagnetic radiation coming from all directions and appearing to be from a blackbody that is at 3 K. What is this radiation?
It's radiation left over from early in the history of the universe when things were much hotter and denser than now.
Wavelength equation
L=v/f v=velocity, f=frequency
Omega centauri
Largest and brightest globular cluster today. Has ~ 10 mill stars
What is the main evidence that the Universe is expanding?
Red shifts of the light from distant galaxies show that they are receding from us, and that the farther away they are, the faster they are receding.
Many notes on a piano have three strings that should be tuned to the same frequency. Suppose one of these vibrates at 256 Hz and another at 260 Hz. What will a piano tuner listen for as she adjusts the strings?
She will hear a note at 258 Hz that varies in its loudness at 4 Hz. She will adjust one of the strings until the loudness variation goes away.
Last year Samsung recalled all of its newest, most chic and trendy smart phones because the battery sometimes exploded or caught fire. Why did those and other similar batteries sometimes catch fire?
Some failure inside the battery causes large current to flow, which heats things too much.
the open ocean, a tsunami wave travels hundreds of miles an hour, but we saw in the videos that, if you were paying attention to your surroundings on shore you could probably outrun it? What's going on?
The wave lengths of tsunami waves are tens or even hundreds of miles. Thus the water at the shore rises and falls slowly.
First observed object we are confident is from outside of our solar system.
"Oumuamua." It's moving super fast. Is only seen as a small dot with our best telescopes. Use it's speed and brightness to see how far away it is and the material its made of.
The wavelength of green light is about 5 X 10-7 meters = 0.0000005 meters. figure out the frequency. If v=FL, then F= V/L
(300,000,000 meters/second) / (0.0000005 meters) = 3 X 108 / 5 X 10-7 = (3/5) X 1015 = 6 X 1014 Hz = 600,000,000,000,000 Hz
Some undersea earthquakes cause tsunamis (sometimes mistakenly called tidal waves). If you are on shore, but near by, these are very dangerous. How far away across the ocean might a tsunami travel?
*Around the world, across the ocean
A water wave has a wavelength of 10 meters and a frequency of 2 Hz (2 cycles per second). What is the velocity of the wave?
10 meters X (2 /second) = 20 meters/second
what will happen in US if GW steps not taken
10% or 1/10 of our GDP by 2100
Some politicians say, correctly, that "the climate has always changed." Thus, they argue, we don't have to worry about climate change. What is the approximate length of time for which the climate has been fairly stable?
10,000 years, since the end of the most recent ice age.
Cooling during the most recent big ice age, which ended about 12 or 14 thousand years ago, was about
11 F, 5 or 6 C
The age of the Universe is about
13.8 billion years.
At the time Dr. Muller wrote our text book, which year had the warmest worldwide average temperature?
1998 global warming did not pause after tho cont to increase seen in 2014, 15, 16
Dr. Leikind is "color-blind." This means that
He has trouble distinguishing colors that differ by small amounts of red.
Donald Trump remarked in a Tweet last week that the Macy's Thanksgiving Day parade took place on a record cold day for the parade. He thought that this showed that global warming wasn't happening. This tweet was ignorant and foolish. Why?
He is confusing weather and climate.
What did painter Georges Seurat do in th 1880s that is similar to todays TV screens and computer displays
He painted with dots of saturated colors that our eyes add together to produce colors. This meant his paintings use additive color mixing instead of subtractive mixing which is what painters usually use. Our TV and computers do the same to day.
Why did Dr. Leikind have you hold your thumb up at arm's length and wink at it?
He was showing you a method (in this case of the demonstration) to measure the length of your arm that astronomers use to measure the distance to some stars.
I say that within your lifetimes, Senator Scott's private house will be in trouble. What's the problem?
His house will be flooded, probably by a storm, as the sea level rises. Eventually the rising seas will put his property underwater. They will do this to his house even if he does not believe in global warming.
I, and about 5% of men and a few women, are "red-green color blind." But I assure you that I can perfectly well see the difference between red and green traffic lights. So, what's my problem (with colors)?
I do OK with intense or saturated colors, but have trouble distinguishing nearby colors and especially pastel colors
The United Nations has organized the world's climate scientists to issue periodic, major reports that summarize our knowledge of climate change and global warming, and to tell us what the scientists expect for the future. The acronym (initials) for this important organization is
IPCC
Pit vipers (kinds of snakes) and mosquitoes see using visible light, but they an also sense
IR
special relativity ex
If someone else is shining a laser beam and you guys are going diff speeds you will measure it at a different velocity than other person. Yet we always get the same number for the speed of light. Einstein was thinking about these kinds of stuff in HS!
Sometimes a photograph of your sweetheart taken indoors shows him or her with ghoulish red eyes. What causes this?
If the flash is close to the camera lens, light from it enters the subjects' eyes, reflects from the retina, and comes right back out, reddened by the blood in the eyes' blood vessels.
Why do we call coal, oil, and natural gas fossil fuels?
Millions of years ago, ancient plants converted the Sun's energy into plant stuff, so we are using ancient sun light when we burn these fuels.
Where does most of the Earth's energy come from?
Most of the energy flowing around the Earth is from the Sun. Our so-called fossil fuels all contain energy that came from the Sun millions of years ago, and that we release now.
If you are buying clothes in a department store, it is a good idea to walk outside to check the colors. Why is that
Most stores use fluorescent lighting. This light appears white to our eyes, but its spectrum is not like sunlight. To see the colors as you'd see them in normal, sunlight (or incandescent light), you have to get away from the fluorescent light and into sunlight.
When I was young, a teenager, I was a little near-sighted, and I had to wear glasses to see things far away clearly. Now that I is an old guy, I haves to wear reading glasses to see things close up clearly. What happened to me, and happens to many old people?
My eyes' lenses gradually stiffened as I got older, and my tiny eye muscles cannot adjust the lenses sufficiently to see up close.
Inca Mummies
Native Americans also smart ppl. Mummies survived for 100s of years. Maybe 800 or even a thousand. Three children found by archeologists they had been given drugs and alcohol to be more compliant when they were sacrificed.
You have radioactive potassium-40 in your body. During the next few days, some of the potassium-40 nuclei will explode or decay. What is the difference between those that explode and those that do not?
Nothing. There is no difference between them.
The same note is played on two pianos, and you hear a beat at 1 Hz. We deduce
One or both pianos are out of tune.
Keep in mind the meaning of the important wave relation, velocity = frequency times wavelength. The highest C on a piano has a wavelength of about 6 inches. It's frequency is 2096 Hz.. Go six octaves down: 1 foot, 2 feet, 4 feet, 8 feet, 16 feet, 32 feet. What's the wavelength of that C? It's the lowest C on the piano.
2048 Hz, 1024 Hz, 512 Hz, 256 Hz, 128 Hz, 64 Hz, 32 Hz. So that note is 32 Hz
You see a lightning strike and count the seconds until you hear the thunder. You count three seconds. The speed of light is a billion feet per second. The speed of sound is a eleven hundred feet per second. How far away was the lightning strike?
3 seconds X 1100 feet/second = 3300 feet
If the United States reduced CO2 emissions to those stated in the Kyoto Treaty, from 2008, but developing nations, especially China and India, continued to increase their use of coal as the same rate as today, how long would this delay the rise in the Earth's temperature?
3 years
The greenhouse effect, today, warms the Earth by about
30-35F
The average temperature of the surface of the Earth, averaged over day and night, over the seasons, and over the land and ocean surface, is about
57 or 58 F
What's a good guess for the wavelength of the notes near to the middle of a piano, which is also about that of the human voice?
A few feet.
Tell me about the Harvard Observatory "computers."
About 100 years ago a woman Henrietta Leavitt discovered the next step to measuring the universe after trigonometry. If she could find out the period a star got bright and dim she could figure out how far away the stars were. Specifically Charles Pickering, an astronomer, encouraged a group of women to conduct their own scientific research. Henrietta was apart of this group known as the women computers at the Harvard College Observatory.
part of general theory whats centripetal force
Centripetal force shows that if a person was driving a car around a curve, unattached objects will move toward the outside of the curve. From this idea that objects can shift as if pushed on by another force Einstein concluded that gravity was a fictitious force.
A category 1` hurricane has winds that are around 75 miles per hour. A category 4 hurricane, which is what Michael was when it hit the base has winds around 150 miles per hour. How much greater was the force of Michael's winds on the buildings than if it had been a category 1 storm?
About 4 times stronger. because air resistance is proportional to the wind velocity squared.
Dr. Muller says that former Vice President Al Gore and other "alarmists", such as Dr. Leikind, are causing a lot of trouble. What does he say that they are doing?
Although their intentions are good, the alarmists are exaggerating to the point of falsehood, Trying to impose impractical and ineffective international treaties on the United States, Giving people the idea that scientists are certain about their predictions for the future climate.
To get a picture of the hydrogen atoms in your brain, your doctor will order which of these tests?
An MRI = Magnetic Resonance Imaging.
ch 12
Armageddon
Tell me about the 3 K blackbody radiation.
Based on the Big Bang it was predicted that the early universe was so hot and it would be full of electro-magnetic radiation and black body spectrum that an object would emit if it was a temperature of 3K as the ancient high temperatures decreased as the universe expanded. Astronomers have detected this radiation and it serves as proof that the Universe was once very hot and dense.
special theory of relativity
Basically space and time. Einstein's theory that no particle of matter can move faster than the speed of light and that motion can be measured only relative to a particular observer
The Heisenberg Uncertainty Principle says that
Because quantum things have properties of waves and of particles, some of those properties cannot be precisely specified.
You are broiling a steak in your oven. You have set the rack and pan so that the steak is close to the top heating element, and you set the oven to the Broil setting, which is the highest temperature possible in the oven. Then, you propped open the oven door a few inches. Why did you do that?
Broiling uses infrared radiation from the heating elements to heat the steak, and you don't want the oven's air to heat up and warm the steak too.
more on stars based on color
Blue stars are 24k peak of radiation in ultra violet. More blue light than red like Sun is white
If we imagine the Earth is the size of a big marble, about an inch, then roughly how far away is the Sun, which would be about the size of a big (8 feet) beach ball?
Earth about 8000 miles in diameter. The Sun is about 90,000,000 miles from Earth. Divide 90,000,000 by 8,000, 90,000 / 8 equals about 11,000 inches. Twelve inches in a foot, so a little less than 1000 feet
Light
Electromagnetic radiation that lies within the visible range.
Why do the atoms of each element emit (or absorb) only particular colors of light?
Electrons fit into atoms in particular standing wave patterns, each of which may have distinct energy. Each element has a unique pattern of standing waves because each element has a specific number of protons and of electrons.
As ice from land, such as Greenland and Antarctica melts, and as the oceans expand a little as they warm, the sea level will rise around the world. Many places can build sea walls, like the Dutch have done. But this won't work to save Miami Beach or Miami. Why not?
Florida's bed rock is limestone, which is porous. Sea water will just go under a sea wall.
In the 1980s, many nations signed a UN treaty that banned the use of Freon in refrigerators and air conditioners and elsewhere. They did this to stop the growth of the ozone hole near Antarctica. What did Freon have to do with ozone and an "ozone hole?"
Freon that leaked from equipment mixed in the atmosphere to high altitudes, and it destroys ozone. Too much ultraviolet light would reach the surface if the ozone disappeared.
What's general relativity all about?
General relativity is the second part of Einstein's theory of relativity. It is essentially about gravity. The idea was that all objects accelerate at the same rate in a gravitational field. The mass of the objects is irrelevant, and would only be significant if it was not a gravitational force.
Tell me about kilo, mega, and giga. What are they? What do they mean? Also, milli, micro, and nano
Giga means a billion=1,000,000,000 or 10^9. Mega means a million= 10^6. A kilo is a thousand 10^3, Milli is one thousandth=0.001 10^-3, Micro is a millionth= 10^-6, nano means 10^-9 a billionth.
During Thanksgiving week Donald Trump tweeted that the unusual cold in the Northeast showed that the Earth wasn't warming. On Friday of that week, his administration relaesed a massive report on global warming. What did that report say?
Global warming was already causing plenty of bad effects and that things would get worse.
what elements in first few minutes of U
H and helium
Cameras use lenses to make images. Our eyes use lenses to make images. How can a pin hole camera, which doesn't have a lens, make an image?
Light travels in straight lines, rays, so each tiny part of the object and the tiny pin hole define a straight line to leads to a tiny part of the screen on which the image forms
light travels faster than sound. How much faster? Sound travels about 1100 feet/second or about 330 meters/second.
Lignt travels about a billion feet per second, or 1 foot per nanosecond, or about 1000 feet per microsecond. I've given you the same speed in different units
I had you look at the cube corner from three different directions? What was going on in the different directions? What was remarkable about what you saw in each direction?
Looking face on to one of the mirrors, you just saw a regular mirror image, reversed left and right. Looking directly at one of the lines were two mirrors meet, you saw an image but it was not reversed left and right. Light bounced from both of the mirrors. Looking into the corner, you saw the image no matter how you moved the cube corner around. The light bounced on all three mirrors
Scientists say that about 1/4 of the universe is "dark matter." What's that?
Stuff that is not like the normal matter around here and that does not emit or absorb radiation, but astronomers can see that it exerts gravitational force.
Why is the Earth's radiation at longer wavelengths (and lower frequencies) than the Sun's?
Sun like a bill times hotter and a bill times farther away, thus has higher frequency and shorter WL
A person standing 10 or 20 miles from an earthquake's epicenter (the point on the ground above where the rocks broke or slipped) may feel two periods of shaking. Why?
The P (pressure) waves and the S (shear) waves travel at different velocities. They start out when the quake occurs and reach the person at different times
Donald Trump announced that he will withdraw the US from the Paris Accords. What are they about?
The Paris Accords are an international treaty in which the world's nations pledge to reduce their emission of carbon dioxide.
The Earth absorbs visible and near infrared (short wavelength infrared) from the Sun. Then it emits far infrared (long wavelength infrared). Why does it emit longer wavelengths than it absorbs?
The Sun emits lots of visible and near infrared light because it is a 6000 K blackbody emitter, and the Earth emits far infrared because it is about a 300 K blackbody emitter.
You are standing outside in an open parking lot on a hot Tampa day, and you are looking at the front of the stores over the top of your car. The store fronts appear to flicker and wiggle. What's going on?
The Sun's radiation hitting the top of your car is warming the air near to it, making it less dense. Waves bend when they travel in materials that are not the same everywhere.
If the radiation from the Sun goes through the atmosphere, downward, why doesn't the radiation from the Earth get through the atmosphere, going upward?
The Sun's radiation is in the visible and near infrared region because the Sun is an incandescent object with a temperature of about 6000K. and the air is transparent to radiation in those ranges. The Earth radiates as a 300 K object, in the far infrared, and water vapor, carbon dioxide, and other gases, absorb radiation in that range..
What is the Trump administration up to? I mean with respect to global warming.
The Trump administration does not believe that humans are responsible for global warming and asserts that steps to deal with global warming will cause widespread economic damage to the US. Therefore, it is undertaking to reverse the steps taken by the Obama administration to deal with global warming.
What is waving in a sound wave?
The air pressure
How does the Pepper's Ghost illusion work? Have you seen this effect?
The audience sees a direct object and an object reflected from a piece of glass. The two objects appear superimposed.
What about the climate has been unusual for the past 10,000 years, and why does this matter for whether or not global warming is a significant problem?
The climate has been generally stable since the end of the last Ice Age about 10,000 years. This period includes the entire history of human settled agricultural civilization. The few, localized and small variations in the climate have had signficant effects on human life. But in the past 100 years we have driven the Earth's surface faster and farther than any variation during the last 10,000 years. There is no sign that we will reverse this trend.
The retina, the thin layer at the back of your eye has two kinds of tiny light sensors, rods and cones. Which ones are sensitive to light of different colors?
The cones. The rods only detect light or not light, so they "see" in black and white.
n the special relativity video with the curly-haired guy, we saw a bowl of popcorn sit on a box when he was in his backyard, and we saw the bowl of popcorn sit on a box when he rode in the van. This showed us an example of the fact that the laws of physics (in this case Newton's first law) are the same in laboratories no matter how they move, as long as they move a constant velocities. What made the guy and the bowl of popcorn fly of the seat and the box?
The driver stepped hard on the brakes, but the guy and the popcorn kept moving as before.
Superconductors allow electrons in wires to move without losing energy, without electrical resistance, because
The electrons in the electrical current cannot lose energy by colliding with the wire's atoms because there is an energy gap, and they'd have to make too big a jump in energy.
On a piano, musicians label the white keys 8 letters that repeat. The pitch or frequency increases moving left to right on the keyboard. Two corresponding keys, say the two Ds I've marked in bold font with an underscore, are one octave apart. What is the difference in the sound waves of those two notes?
The frequency of the higher note is two times the frequency of the lower note.
The Fukushima earthquake that caused the great tsunami was close to Japan, but the waves went across the Pacific. The energy of a wave is proportional to the square of its amplitude. Keeping the Conservation of Energy in mind, why was the size of the waves in Hawaii so much smaller than they were in Japan?
The great wave spread out more or less as a circle. As the wave traveled greater and greater distances, the wave energy was spread out over more and move of the larger circle's circumference. Thus the amplitude of the wave decreased.
What is the wave property of electromagnetic waves that allows light traveling in fiber optics to carry much more information (encoded as 1s and 0s) than radio waves traveling in the air or in cables?
The higher the frequency, the faster it can make 1s and 0s, so the more information it can carry.
Laser light is useful for several reasons.
The light from a laser is at a single frequency (or color), light from a laser can be very intense, light from a laser points in one direction and doesn't spread out much.
An ocean wave reaches a harbor, which is shaped like this: C ||||. The wave comes from right to left. When it hits the harbor mouth, the part that enters the harbor spread out after it passes the narrow mouth. Later another ocean wave arrives, but it has a longer wavelength: C | | | | |. It also spreads out. Which one spreads out the most?
The long wavelength one spreads the most when it passes the harbor mouth.
Dr. Muller describes some interesting examples in which waves bend, or don't go in straight lines. What causes this to happen?
The material in which the wave moves is not uniform or constant.
What is the maximum speed of anything in the universe? Why do physicists believe that nothing can go faster than this speed limit?
The maximum speed of anything in the universe is called the speed of light or "c." It is about a billion feet per second. Physicists think c is the absolute speed limit of the universe because being able to go above the speed of light has too many implications that contradict common sense. Such as if something goes above c it could technically reverse the order of events for different observers. This would go against cause and effect like saying a man was dead before the gun was actually fired
Dr. Muller showed a photograph taken with an infrared camera at night. You could see some guys cutting and climbing over a fence. Why did this worK?
The men are warmer than the night air and the fence. Thus they radiate much more infrared than the air or fence. Their faces are much brither than their clothes too. The camera is measuring the amount of infrared hitting the film or sensor at each location.
If you send two waves at each other, they do not bounce. They pass through each other, making a pattern where they overlap, and emerging unchanged and going in the same direction as before. What is the name for this wave property? What is going on in this case?
The name of the property is wave interference. Each waving thing, a drop of water or a small blob of air and so on, moves according to the sum of the instructions from each wave. The waving thing may move extra far or strongly, or not at all, depending on how each of the waves tells it to do. Even if the waving thing does not wave, the two waves are still present, moving through that location. This may produce a complicated wave pattern where the waves overlap.
Coral reefs around the world, home to many colorful and interesting sea creatures, are losing their pretty colors, bleaching and dying. why?
The oceans are warming.
Which quantum effect is the operating principle in the cameras in your computers and cell phones?
The photoelectric effect
The peak days of Japan's cherry blossoms in their ancient capital, Kyoto, are about 2 weeks earlier in the year these days than they were before about 1800. Why?
The trees have shifted their blossom times earlier in the year as the warmth of spring has moved earlier in the year because of global warming.
Several times during this course, Dr. Leikind has explained how scientists figure out the facts they announce. For example, he told you how physicists figure out the carbon dioxide in the atmosphere more than a hundred thousand years ago before there were human beings or scientists. What important fact was he explaining to you when he told you about the Cosmic Distance Ladder?
The universe is immense, and we are small in comparison.
Dr. Muller was skeptical that the world's climate scientists had figured out the Earth's surface temperature from thermometer records and organized a project to independently check their work. What did he conclude when he published his team's results and wrote an op-ed essay in the New York Times, in 2012?
The world's climate scientists had done their work correctly.
About 10 times as many men as women are "color blind." What does it mean to be "color blind
There's something wrong with one of their cone pigments, and they confuse some colors.
What is the cosmic distance ladder? What are some of the "rungs?"
These days, astronomers use radar to measure distances from Earth to other planets, and also parallax, which is the apparent shift of position of nearby things compared to far away things when your viewing point shifts. This is the first rung of the cosmic distance ladder, and it tells us the size of the Solar System, and the Earth's orbit. Using the distance across Earth's orbit as the base of a triangle, astronomers use parallax to find the distance to the closest stars. Then we use Cepheid variable stars to measure the distance to farther stars in our galaxy, and to stars in distant galaxies. The last steps involve standard candles, such as Type Ia super novas, and finally, we measure the red shift of light from the most distant galaxies to place them in the cosmological expansion of U
Astronomers and physicists are searching for WIMPS (which is an acronym for weakly interacting massive particles) and MACHOS (for massive compact halo objects), but no one has ever seen one. Why are these scientists searching for them?
They are trying to figure out what makes up dark matter.
Computer screens and magazine photographs only have three colors (and black), if you look with a magnifying lens. How do they fool us into seeing many colors?
They vary the amount of each of the three colors, and our eyes add them together to create a mixed color.
Dr. Hafele and Dr. Keating bought first class round-the-world airline tickets going in both directions for some super accurate atomic clocks. What were they doing?
They were trying to test the twin paradox about how time changes when its moving versus being stationary. Specifically they were proving that moving clocks run slower than stationary ones.
What does this mean? E = mc2
This is Einstein's famous energy equation. E being energy; which is proportional to m (mass) and c being the speed of light, which is constant here. Basically saying that changes in mass and energy must be accounted for. From his theory we learned that many things are mingled together such as space and time. Like how mass seemed different when an object was moving versus when it was at rest.
There are several types of earthquake waves: P or compressional waves, S or shear waves, and L or surface waves. What is the name for the wave property that makes these three types of waves different? What is the meaning of that property?
This property is known as polarization, which is the relation between the direction the waving thing of a wave is waving and the direction that the wave is going. P waves have longitudinal polarization. The ground shakes back and forth in the direction that the wave moves. S waves have transverse polarization. The ground shakes side to side or up and down relative to the direction the wave travels. L waves, surface waves, have a complicated combination of longitudinal and shear motions.
Wave-particle duality refers to the fact that in the microscope world,
Tiny things are both waves and particles at the same time.
What is a quantum leap, or a quantum jump?
Tiny things, such as atoms that involve tinier things bound together, can only exist in certain energy states. When the tiny thing changes its energy, by emitting or absorbing energy, it can only do this by jumping to another allowed energy.
they sit down, and the fans in the next section stand and cheer, and so on. This goes around the stadium, perhaps more than once. This is called "the Wave." What is the polarization of the Wave?
Transverse because the waving stuff, fans, are standing and sitting while the Wave moves along the stands.
The tsunami waves from the great Fukushima earthquake that we watched arrive in Hawaii didn't look at all ocean waves, breakers, coming ashore at the beach. Why not?
Tsunamis have wavelengths of tens or hundreds of miles. Breakers have much shorter wavelengths.
Your eye has 2 lenses
Two lenses: "the lens" (flexible lens) and the cornea.
The Sun's ultraviolet radiation breaks apart oxygen molecules, O2, and sometimes one of the oxygen atoms sticks to a nearby oxygen molecule, forming ozone, O3. Mostly this happens high in the atmosphere, forming a thick layer that absorbs much of the Sun's ultraviolet radiation. Why is this important to life on Earth?
Ultraviolet light damages life's chemicals, which is why ultraviolet light is used to sterilize medical instruments.
The speed of sound in air here at the Earth's surface is about 1000 feet/second. The frequency of a piano's middle C is about 250 Hz = 250 /second. What is that note's wavelength?
V [feet/second] = L [feet] X f [ /second] 1000 = L * 250 • L= 4 • 1/250=1000 * 4
Illusions cast doubt upon the use of our senses and reason to find truth. What can we do about this problem?
Various methods. For example, investigate the same phenomenon from different points of view or using different methods. Try to make objective measurements, not subjective ones.
During the American Civil War, there were several famous battles in which armies engaged in ferocious combat, but the commanding general of one side, or the other, at his headquarters a few miles from the battle ground did not know that his men were in desperate circumstances until messengers arrived. Why didn't anyone at headquarters hear the battle sounds?
Warmer air near the ground and cooler air higher up bent the sound waves upward, and headquarters were in a shadow zone.
In the classroom demonstration with the waves on the string, Dr. Leikind showed you that only certain wavelengths and frequencies could "fit". The string vibrated with a steady pattern, and places that didn't vibrate. That little machine that made the waves was wiggling up and down, making waves, even when they didn't "fit". What has happening to the waves then?
Waves left the machine end of the string and reflected from the other end. Since the wavelengths didn't "fit" into the string, these waves added and subtracted randomly and averaged out to zero.
Which of these is a transverse wave?
Waves on the surface of the ocean.
What does modern quantum physics tell us about whether we have free will?
We believe that our minds arise from our brains through the workings of natural law. Thus any choices we make, whether to have vanilla or chocolate ice cream, must be the prescribed outcome of those natural laws operating through the environment on our brains. But quantum physics also tells us that the microscopic world has a kind of random unpredictability. Some people hope that this provides room for us to have free will,
A galaxy is an immense collection of stars held together by gravitation. How many galaxies are t
We can see tens of billions of galaxies with our best telescopes.
Dr. Leikind showed you a standing wave video demonstration with the vibrating string. It was a one-dimensional illustration of standing waves. What did that demonstration show?
When waves are trapped in a limited space, only certain wavelengths and frequencies can fit.
A CT scan is a medical test that produces cross-sectional images of a patient's body. What form of electromagnetic radiation does a CT scan use?
X-rays
Are waves up here in the macro, large world, like ocean waves, quantized the way tiny things are quantized?
Yes, but the different waves are too close together in energy in a big thing for the quantization to be noticeable.
In special relativity, there is a maximum speed limit, and particles with no rest mass such as photons, are the only things that can go that fast. Special relativity tells us about some weird things that would happen if someone managed to go faster than this maximum speed limit. What is one of them?
You could go backward in time, and do things like kill your grandfather before he had his son or daughter who became your parent.
To tell if the gas in a glass tube is hydrogen or helium (both are colorless gases if you just look at them) you would run electric current through them. How would that help you?
You could look at them through those funny spectrum glasses, and you'd see that their emitted light is different.
If you mix three primary colored lights, such as red, green, and blue, you get white light. What do you get if you mix three primary colored paints, also such as red, green, and blue?
You get a muddy brown color.
If you were to see me zooming past you carrying one of those meter sticks in the front of the class (holding it along the direction I am moving), what would you think about my meter stick?
You would think my meter stick was too short.
Dr. Muller and Dr. Leikind have wrist watches with super-duper tritium (radioactive isotope of hydrogen) powered glowing numbers. If you were to see Dr. Leikind zooming past you what would you say about whether his watch was working correctly?
You'd say his wrist watch was running slowly compared to yours.
The most recent time at which there were higher carbon dioxide levels in the atmosphere than there are today was about
a few million years ago.
The Andromeda Galaxy is the most distant object that you can see with your unaided eyes. How long does it take light to get to us from that beautiful spiral galaxy?
a few million years.
Most of the mass of the Universe is
dark matter
Which has higher frequency, red light or blue light?
blue light has a higher frequency than red light.
The Universe's hydrogen, and much of its helium (and small amounts of other light elements) appeared early during the Universe's life, other elements, such as oxygen, nitrogen, and carbon, were manufactured
by fusion reactions inside large stars.
About 20 years ago, certain spray cans, used to apply paint, hair spray, deodorants, and many other products, were banned by an international treaty. These spray cans used which of these propellants?
chlorofluorocarbons (CFCs)
The least expensive method to reduce the amount of carbon dioxide we put into the atmosphere is
conserve energy to reduce our use of carbon burning energy.
To astronomers' surprise, about 20 years ago astronomers observed that the Universe's expansion is accelerating instead of slowing down from gravitation. What is the name for what they guess might be dong this?
dark energy
