PHYS 187 Final questions well
answered graded A+ passed
A spaceship is headed toward Alpha Centauri at 0.999c. According to us, the distance to Alpha
Centauri is about 4 light-years. How far away is Alpha Centauri according to the travelers in the
ship? - correct answer ✔✔quite a bit less than 4 light-years
What is the smallest mass a newborn star can have? - correct answer ✔✔80 times the mass of
Jupiter
Suppose you put two protons near each other. Because of the electromagnetic force, the two
protons will - correct answer ✔✔repel each other
What is interstellar reddening? - correct answer ✔✔Interstellar dust absorbs more blue light
than red light, making stars appear redder than their true color
Which layer of the Sun do we normally see? - correct answer ✔✔photosphere
How does the Sun generate energy today? - correct answer ✔✔nuclear fusion
If we could measure the mass of the spaceship as it goes by, what would it be? - correct answer
✔✔Its mass is greater than its rest mass
How would we view time (clocks on the spaceship as it goes by? - correct answer ✔✔Their
clocks are going slower than ours
,Al is moving by you at a very high speed (close to the speed of light). You get out a clock and
measure 10 seconds going by. If you also watch a clock in Al's ship, how much time will you see
it
record during your 10 seconds? - correct answer ✔✔AI's clock will record less than 10 seconds
In relativity, two people share the same frame of reference only if - correct answer ✔✔they are
not moving relative to each other
From the center outward, which of the following lists the "layers" of the sun in the correct
order? - correct answer ✔✔core, radiation zone, convection zone, photosphere, chromosphere,
corona
How are wavelength, frequency, and energy related for photons of light? - correct answer
✔✔Longer wavelength means lower frequency and lower energy
You observe a star in the disk of the Milk Way, and you want to plot the star on an H-R diagram.
You will need to determine all of the following, except the - correct answer ✔✔rotation rate of
the star
You observe the same spectral line in two stars that are identical in every way except that one
rotates faster than the other. How does the spectral line differ between the two? - correct
answer ✔✔The line in the faster rotating star is broader
What happens to the visible radiation produced by new stars within a molecular cloud? - correct
answer ✔✔It is absorbed by dust grains and heats up the cloud
If two objects are the same size but one object is 3 times hotter than the other object, the
hotter object emits - correct answer ✔✔81 times more energy
, Why are neutrinos so difficult to detect? - correct answer ✔✔because they rarely interact with
matter
Each of the following lists two statements. Which two are the basic premises for the special
theory of relativity? - correct answer ✔✔1. The laws of nature are the same for everyone.
2. The speed of light is the same for everyone
From laboratory measurements, we know that a particular spectral line formed by hydrogen
appears at a wavelength of 486.1 nanometers (nm). The spectrum of a particular star shows the
same hydrogen line appearing at a wavelength of 485.9 nm. What can we conclude? - correct
answer ✔✔The star is moving toward us
Astronomers estimate that new stars form in our galaxy at the rate of about - correct answer
✔✔a few (2-3) per year
On a Hertzsprung-Russell diagram, where would we find stars that are cool and dim? - correct
answer ✔✔lower right
Which of the following statements about an open cluster is true? - correct answer ✔✔All stars
in the cluster are approximately the same age
When an electron in an atom goes from a higher energy state to a lower energy state, the atom
- correct answer ✔✔emits a photon of a specific frequency
When does a star become a main-sequence star? - correct answer ✔✔when the rate of
hydrogen fusion within the star's core is high enough to maintain gravitational equilibrium
The predictions of special relativity can sound implausible at first. What observational evidence
do
answered graded A+ passed
A spaceship is headed toward Alpha Centauri at 0.999c. According to us, the distance to Alpha
Centauri is about 4 light-years. How far away is Alpha Centauri according to the travelers in the
ship? - correct answer ✔✔quite a bit less than 4 light-years
What is the smallest mass a newborn star can have? - correct answer ✔✔80 times the mass of
Jupiter
Suppose you put two protons near each other. Because of the electromagnetic force, the two
protons will - correct answer ✔✔repel each other
What is interstellar reddening? - correct answer ✔✔Interstellar dust absorbs more blue light
than red light, making stars appear redder than their true color
Which layer of the Sun do we normally see? - correct answer ✔✔photosphere
How does the Sun generate energy today? - correct answer ✔✔nuclear fusion
If we could measure the mass of the spaceship as it goes by, what would it be? - correct answer
✔✔Its mass is greater than its rest mass
How would we view time (clocks on the spaceship as it goes by? - correct answer ✔✔Their
clocks are going slower than ours
,Al is moving by you at a very high speed (close to the speed of light). You get out a clock and
measure 10 seconds going by. If you also watch a clock in Al's ship, how much time will you see
it
record during your 10 seconds? - correct answer ✔✔AI's clock will record less than 10 seconds
In relativity, two people share the same frame of reference only if - correct answer ✔✔they are
not moving relative to each other
From the center outward, which of the following lists the "layers" of the sun in the correct
order? - correct answer ✔✔core, radiation zone, convection zone, photosphere, chromosphere,
corona
How are wavelength, frequency, and energy related for photons of light? - correct answer
✔✔Longer wavelength means lower frequency and lower energy
You observe a star in the disk of the Milk Way, and you want to plot the star on an H-R diagram.
You will need to determine all of the following, except the - correct answer ✔✔rotation rate of
the star
You observe the same spectral line in two stars that are identical in every way except that one
rotates faster than the other. How does the spectral line differ between the two? - correct
answer ✔✔The line in the faster rotating star is broader
What happens to the visible radiation produced by new stars within a molecular cloud? - correct
answer ✔✔It is absorbed by dust grains and heats up the cloud
If two objects are the same size but one object is 3 times hotter than the other object, the
hotter object emits - correct answer ✔✔81 times more energy
, Why are neutrinos so difficult to detect? - correct answer ✔✔because they rarely interact with
matter
Each of the following lists two statements. Which two are the basic premises for the special
theory of relativity? - correct answer ✔✔1. The laws of nature are the same for everyone.
2. The speed of light is the same for everyone
From laboratory measurements, we know that a particular spectral line formed by hydrogen
appears at a wavelength of 486.1 nanometers (nm). The spectrum of a particular star shows the
same hydrogen line appearing at a wavelength of 485.9 nm. What can we conclude? - correct
answer ✔✔The star is moving toward us
Astronomers estimate that new stars form in our galaxy at the rate of about - correct answer
✔✔a few (2-3) per year
On a Hertzsprung-Russell diagram, where would we find stars that are cool and dim? - correct
answer ✔✔lower right
Which of the following statements about an open cluster is true? - correct answer ✔✔All stars
in the cluster are approximately the same age
When an electron in an atom goes from a higher energy state to a lower energy state, the atom
- correct answer ✔✔emits a photon of a specific frequency
When does a star become a main-sequence star? - correct answer ✔✔when the rate of
hydrogen fusion within the star's core is high enough to maintain gravitational equilibrium
The predictions of special relativity can sound implausible at first. What observational evidence
do
