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51 Cards in this Set
- Front
- Back
What is Einstein's first postulate?
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The laws are all the same in all inertial(non-accelerating)reference frames
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two cars hit and both say they were at rest. What do they agree on?
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Relative Velocity
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I am stationary in a reference frame but, if my frame system is not an inertial reference frame, then relative to me, a system that is an inertial reference frame must:
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Be accelerating
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Einstein’s theory of relativity is based in part on which one of the following postulates?
1.Space and time are absolutes 2.The speed of light in a vacuum is the same in all inertial reference frames 3.Energy is conserved only in elastic collisions |
The speed of light in a vacuum is the same in all inertial reference frames
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What is Einstein's second postulate?
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The speed of light in a vacuum is constant in all inertial reference frames--it does not depend on the velocity of the reference frame
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If the back rocket sent out a light pulse to warn the front rocket before the crash, who measures the speed of the light to be the fastest?
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they both measure it the same
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The relativistic effect of time dilation has been verified by which if the following?
1.The discovery of black holes 2.Muon experiments 3.Twin experiments 4.Red shift in distant galaxies 5.None of the above choices verified time dilation |
Muon Experiments
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A muon formed high in the Earth's atmosphere travels at a speed 0.990 c for a distance of 4.60 km (as we see it) before it decays. What is the muon's lifetime as measured in our reference frame?
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1.55e-5 seconds
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A knight on horseback holds a 10-m lance. The horse can run at 0.70 c. (It wins most of its races!) How long will the lance appear to a person that is standing still on the ground as the horse runs past?
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shorter than 10 m
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The observed relativistic length of a super rocket moving by the observer at 0.70 c will be what factor times that of the measured rocket length if it were at rest?
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.71
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According to the special theory of relativity, if a crew watches a movie that is two hours long in a spacecraft that is moving at high speed through space. Will an Earthbound observer, who is watching the movie through a powerful telescope, measure the duration of the movie?
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More than 2 hours
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According to the special theory of relativity, if a 30-year old astronaut is sent on a space mission is accelerated to speeds close to that of light, and then returns to earth after 20 years as measured on earth, what would be his biological age upon returning?
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Less than 50 years old
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We see a spaceship flying past at 0.9c. The captain of the spaceship launches a missile, which she sees leaving her ship at 0.9c out the front. We see the missile traveling at
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A speed less than c
or .99c |
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A baseball at rest has
1. energy 2. mass 3. both |
both
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The number of photoelectrons emitted from a metal surface in the photo-electric effect experiments depends on
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The frequency of the incident light and the work function of the metal
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A beam of visible light is incident on the metal ball of an electroscope (hf < Φ) that is initially negatively charged. The electroscope . .
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nothing happens
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A beam of ultra violet light is incident on the metal ball of an electroscope (hf > Φ) that is initially negatively charged. The electroscope . .
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losses its negative charge
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400-nm wavelength light strikes a metal surface, a stream of electrons emerges from the metal. If the intensity of the light striking the surface is doubled
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more electrons ar emitted, but they do not have a higher energy
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When 400-nm wavelength light strikes a metal surface, a stream of electrons emerges from the metal. If the 400-nm light is replaced with 300 nm and the lamp is adjusted so that the intensity of the light striking the surface is the same as it was for the 400-nm light. With the 300-nm light,
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the electrons emitted are at a higher energy...shorter wavelength
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A beam of ultra-violet light is incident on the metal ball of an electroscope that is initially uncharged. Does the electroscope acquire a charge?
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Yes, it aquires a positive charge
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In the Compton experiment, the wavelength of the scattered light is ______________ the wavelength of the incident light.
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Longer than
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Suppose the momentum of a photon is determined with complete accuracy (the uncertainty approaches zero). The uncertainty in a simultaneous measurement of the photon’s position
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Approaches infinity,
cannot know the location and the momentum simultaneously |
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What did the Rutherford alpha particle/gold foil experiment gave evidence for?
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Nuclear atom
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The green emission line in hydrogen is a transition from an excited state n=4 to n=2. The red line must be a transition from ______ to n=2.
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N=3 red is lower in energy than blue, so a smaller jump in n is needed to produce the light
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What is DeBoglie’s hypothesis?
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E=hf=hc/λ—Energy of a photon
p=E/c=h/λ—momentum of a photon λ= h/p=h/mv—wavelength of a particle If I increase the velocity of a particle, it decrease the wavelength If an electron and a proton have the same wavelength, their momentum is the same but the electron has a much higher velocity. |
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What is the mass of 12C?
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12u
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Notation review for elements
what is Z What is N What is A |
Atomic number-Z, # of protons in the nucleus
Determines which element it is Neutron number-N, # of neutrons in nucleus Mass number- A=Z+N AZX Isotopes—Nuclei of the same element (same Z) with different A (and N) values. |
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Which of the following is an isotope of carbon?
a.13C6 b.13N7 c.13C7 d. they are all isotopes of carbon |
A. same number of protons, has one more neutron
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Which of the following is not a correct notation?
a. 13C6 b. 13N7 c. 13C7 d. they are all correct |
C.
13C7 says that there are 7 protons which lets us know that it is actually Nitrogen not carbon |
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How many Protons does 263Sg106 have?
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106
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How many Neutrons does 263Sg106 have?
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157
263-106=157 |
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What is The half-life of a radioactive material is?
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The time required for half of the original number of atoms to decay.
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You start with 1000 dice. Every time you get a six you take it out. How many rolls is a half-life?
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4 rolls
there is a 1 in 6 chance everytime that you will remove a die |
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If I start with 10000 pennies and every time I toss all the coins I remove the tails, how many tosses does it take to get down to less than a dollar left?
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7 tosses
each coin has a 50% chance each toss |
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Over the course of 3 hours, 15% of a radioactive material decays. What is its half-life?
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12.8 hours
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true or false
If a nucleus undergoes radioactive decay it must be older than the other nuclei in the sample? |
False
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The nuclear force is really __________.
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a short range attractive force between nuclear particles.
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Can one element change into another element as a result of radioactive decay?
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yes
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Is Alpha Decay--42He given off in large or small nuclei
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Occurs in large nuclei—the result is a more stable nucleus with more neutrons compared to protons
22688Ra =>22286Rn + 42He |
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What is Beta Decay
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Changes a proton to a neutron or a neutron to a proton--
146C => 147N + -1e + νe 189F => 188O + 1e + νe |
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The neutrino is necessary in some radioactive decay to do what?
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conserve momentum
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What is gamma decay
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photon decay--change from a higher energy state to a lower energy state
152Dy66 => 152Dy66 + photon |
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What type of decay is this?
238U92 => 234Th90 + ? T1/2 = 4.5 Gy |
alpha
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What type of decay is this?
234Th90 => 234Pa91 + ? T1/2 = 24 days |
beta -
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226Ra88 eventually becomes 206Pb82. What is released in this process?
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both alpha and beta, but more alphas than betas
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The boat of a pharaoh was discovered and dated to be 4,500 years old. The wood has ______ 14C6 for every trillion 12C6.
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less than 1 but more than .5. it will have .5 at 5,730 yrs, but we are not there yet
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Penetration depth for different types of radioactive decay
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alpha– only a few cm through air
Beta—only through air—blocked by paper or sheet of metal Gamma rays—short wavelength light—penetrate several cm lead or a meter of concrete. Easily penetrates the skin and interacts with human cells—these are the dangerous ones. |
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If you expose strawberries to high levels of radiation--
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They last longer
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What is nuclear fusion?
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the reaction that generates the sun's energy
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what does sustained nuclear fission require?
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1. a critical mass
2. incident neutrons |
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what two factors determine whether the nuetrons will hit another Uranium?
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How fast they are moving
How far they move before they are out (critical mass) |