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40 Cards in this Set
- Front
- Back
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Key Ideas of Special Relativity
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1. No material object can travel faster than light
2. If you observe something moving near light speed: Its time slows down, Its length contracts in direction of motion, Its mass increases; 3. Whether or not two events are simultaneous depends on your perspective |
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Relativity of Motion
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Motion is not absolute- we must measure speed of one object relative to another
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Absolutes of Relativity
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1. The laws of nature are the same for everyone
2. The speed of light is the same for everyone |
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How did Einstein think about motion?
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Motion must be defined with respect to a reference frame
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What's surprising about the absoluteness of the speed of light>
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Velocities in different reference frames do not add up like we expect them to because the speed of light is same for everyone
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Why can't we reach the speed of light?
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No matter how fast we go, light will always appear to move away from us at speed c.
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Relativity Factor formula?
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square root of (1-v^2/c^2)
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How does relativity affect our view of time and space?
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- Time slows down for moving objects
- Lengths shorten for moving objects - Mass of a moving object increases - Simultaneity of events depends on your perspective |
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Do the effects predicted by relativity really occur?
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Relativity has been confirmed by many different experiments
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Paradox
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a situation that seems to violate common sense or to contradict itself
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time dilation
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Time is expanded in a moving reference frame
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General Relativity
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-Gravity arises from distortion of spacetime
-Time runs slowly in gravitational fields -Black holes can exist in spacetime -The universe may have no boundaries and no center, but may still have finite volume |
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Gravitational waves
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Ripples in the fabric of spacetime caused by rapid changes in the motion of large masses
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Rubber sheet analogy
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heavier weights cause a greater distortion of the rubber sheet
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The Equivalence Principle
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all motion is relative, the effects of acceleration are exactly equivalent to those of gravity
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Is Spacetime different for different observers?
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No, spacetime is the same for everyone
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Vertical wordline
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no motion
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Diagonal wordline
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constant-velocity motion
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Curved wordline
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accelerating motion
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How does black hole happen?
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The curvature gets so great that it would be like a bottomless pit in spacetime. the object of fixed mass shrinks, the gravity gets stronger and the escape velocity gets larger
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Event horizon
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point of no return
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How does gravity affect time?
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Time runs more slowly at lower altitudes in a gravitational field
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Gravitational Lensing
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when curved spacetime alters the paths of light rays, shifting the apparent positions of objects
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How do we test the predictions of the general theory of relativity?
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Precession of Mercury
Gravitational Time Dilation Gravitational Lensing |
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Gravitational equilibrium of the sun
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The outward push or pressure from very hot expanding gases is balanced by the strong inward pull of gravity
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How far can we see into the Sun? What layer?
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Photosphere
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Corona
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outermost gaseous layer of the solar "atmosphere"
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The solar wind
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a flow of charged particles, protons, and electrons
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chromosphere
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the middle layer of the solar atmosphere. pinkish
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What comes in and what comes out of the nuclear fusion process?
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In: 4 protons
Out: Helium nucleus, 2 gamma rays, 2 positrons, and 2 neutrinos |
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Luminosity
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amount of power a star radiates (energy per second)
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Apparent brightness
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Amount of starlight that reaches Earth
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O B A F G K M
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Oh Be A Fine Girl Kiss Me
Only Boys Accepting Feminism Get Kissed Meaningfully |
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Sun's life expectancy
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10 billion years
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High Mass star
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High Luminosity
Short-lived Large Radius Blue |
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Low Mass star
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Low luminosity
long-lived small radius Red |
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What are the two things that the Hertzsprung Russel Diagram deals with?
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Luminosity and Temperature
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How do we measure a cluster's age?
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by finding the main sequence turnoff point on an H-R diagram of its stars
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White dwarfs
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"dead" core, remaining embers of former giants
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Why do the properties of some stars vary?
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Some stars fail to achieve a proper balance between the amount of fusion energy welling up from their cores and the amount of radiative energy emanating from their surfaces.
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