pha exam 3 questions & answers 100% CORRECT 2024/2025
Suppose you are on a spacecraft flying away from Earth at half lightspeed. If you share a live video chat with your friend on Earth, what will you perceive about their rate of speech? - ANSWERSYour friend will appear to speak more slowly th...
Suppose you are on a spacecraft flying away from Earth at half lightspeed. If you share a live video chat
with your friend on Earth, what will you perceive about their rate of speech? - ANSWERSYour friend will
appear to speak more slowly than normal.
What does the equation E=mc2 mean? - ANSWERSMass is a form of energy.
Consider an escalator moving upward at 7 mph. Suppose you are walking upward at 8 mph with respect
to the escalator. What is your speed with respect to the ground? Answer: ______ mph - ANSWERS15
Consider an escalator moving downward at 3 mph. Suppose you are walking upward at 4 mph with
respect to the escalator. What is your speed with respect to the ground? Remember that speed is always
positive. Answer: ______ mph - ANSWERS1
Suppose you are on a spaceship flying toward Earth at half lightspeed (0.5 c). If you shine a laser beam
toward Earth, at what speed will the light strike the planet's surface? - ANSWERSc
Suppose you are on a spacecraft flying away from Earth at half lightspeed. If you share a live video chat
with your friend on Earth, what will they perceive about your rate of speech? - ANSWERSYou will appear
to speak more slowly than normal.
According to Einstein's theory of general relativity, what is gravity? - ANSWERSCurved spacetime
According to observational evidence, how did the Universe begin? - ANSWERSFrom an explosion of
spacetime and energy
What is the most abundant form of energy in the Universe? - ANSWERSDark energy
, What is dark energy? - ANSWERSWhatever is causing the Universe's expansion to accelerate
What is dark matter? - ANSWERSAn unseen source of gravity
Suppose I perform a double-slit experiment on 1,000 electrons. Is it possible to predict the pattern they
will make when they land? - ANSWERSyes
Which of the following best describes the nature of light? - ANSWERSLight is a particle and a wave.
Which of the following best describes the nature of an electron? Assume time is linear. - ANSWERSAn
electron is both a particle and a wave.
an electron has mass. a photon doesn't.
Fill in the blank: a particle of light is called a/an _____. - ANSWERSphoton
Suppose I perform a double-slit experiment on a single electron. Is it possible to predict where the
electron will land? - ANSWERSno
What problems with the Big Bang theory would be difficult to solve without cosmic inflation? Choose all
that apply. - ANSWERS- Uniform temperature of the CMB
- Flatness of the Universe
- Foamlike structure of galaxy superclusters
Order each form of energy according to its abundance in the Universe, from most (1) to least (5) -
ANSWERS1. dark energy
2. dark matter
3. hydrogen
4. helium
5. everything else
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