1. A certain gamma-ray source emits photons that have a 20% chance of being foun
ID: 3896740 • Letter: 1
Question
1. A certain gamma-ray source emits photons that have a 20% chance of being found as an electron-positron pair. The source emits 400 photons. How many individual material particles will be found?
2. By increasing the intensity of a light beam, which of the following will be changed? (multiple answer)
wavelength of the light
frequency of the light
speed of light
energy of each photon
number of emitted photons per minute
color of the light
3. By increasing the frequency of a light beam, which of the following must change? (multiple answer)
wavelength of the light
intensity of the light
speed of light
energy of each photon
number of emitted photons per minute
color of the light
4. In the double-slit experiment with electrons, which of the following is/are predictable? (multiple answer)
which slit each electron passed through
the pattern formed on the screen
where on the screen each electron hits
the probabilty an electron hits a certain area on the screen
5. A man and a woman are talking in the classroom. Which property(s) do their voices (sounds) share in common? (multiple answer)
nothing in common
wavelength
intensity
sound speed
frequency
6. Two electrons are placed 1 cm apart. If double the distance between them, the gravitational force between them becomes
4 times stronger
twice stronger
twice smaller
4 times smaller
7. the mass of atoms is mostly (multiple answer)
protons, neutrons, electrons, positrons, neutrinos
8. The inertia of an object is zero when (multiple answer)
acceleration = 0
net force = 0
velocity = 0
mass = 0
9. True or False? Whenever an object is resting on a horizontal surface, the normal force pushing up on the object is equal to its weight.
10. Why do the astronauts on the International Space Station feel weightless? (multiple answer)
there is no gravity in space, so mg=0
there is no atmosphere in space
the rockets on the spacecraft accelerate the craft at a = g
11. Which of the following are the most fundamental (all the others are ultimately made of them)?
electron, proton, neutron, atom, lepton, quark
12. An astronaut has a mass of 85 kg. What is his weight while he is in the Space Shuttle orbiting at an altitude of 350 km above the Earth? (Please use our definition of weight = force measured on scales, not that used by book = F of gravity).
850 N
0 N
9 N
750 N
13. A satellite is in a circular orbit at an altitude above the Earth equal to twice the radius of the Earth. What is the force of gravity on this satellite compared to that on the surface of the Earth, F?
F/2
F/4
0
F
Thank you!
Explanation / Answer
1) The answer wll be 20% of 400 = 80
2) wavelength , number of emitted photons,color of light, frequency of light
3)wavelength of the light,energy of each photon,number of emitted photons per minute, color of the light
4)which slit each electron passed through
the pattern formed on the screen
where on the screen each electron hits
the probabilty an electron hits a certain area on the screen
5)
6)4 times smaller
7)protons, neutrons
8)acceleration = 0
net force = 0
9)False
10)there is no gravity in space, so mg=0
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