True/False
Indicate whether the
sentence or statement is true or false.
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1. |
The
speed of light in water is  ,
where n = 1.33 is the index of refraction of water. The speed
of light in water is thus less than the speed of light in a vacuum.
This fact violates the speed-of-light postulate of the special theory
of relativity.
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2. |
We
customarily say that Earth revolves around the Sun. We can also say
that the Sun revolves around Earth.
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3. |
If
events E1 and E2 are simultaneous in an inertial
frame, then no observers stationary in the same frame will regard E1
as occurring before E2.
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4. |
Any
two observers moving with a clock will agree on the rate at which it
ticks.
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5. |
Any
two observers moving relative to each other, and simultaneously moving
relative to a clock, will agree on the rate at which the clock ticks.
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6. |
An
observer moving with a clock, measuring the time between ticks, measures
the proper time between ticks.
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7. |
Earth
rotates on its axis once each day. To a person observing Earth from
an inertial frame of reference in space, that is, stationary relative
to Earth, a clock runs slower at the North Pole than at the equator.
(Ignore the orbital motion of Earth about the Sun.)
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8. |
A
young astronaut has just returned to Earth from a long mission. She
rushes up to an old man and in the ensuing conversation refers to him
as her son. She cannot possibly be addressing her son.
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9. |
An
object will be greater in length if the observer is moving with the
object than if the object is moving relative to the observer.
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10. |
An
observer at rest relative to a moving object measures the object’s
proper length.
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11. |
Relativistic effects such as time dilation and length contraction
are for practical purposes undetectable in automobiles.
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12. |
The
total relativistic energy of an object is always equal to or greater
than its rest mass energy.
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13. |
Since
rest mass is a form of energy, a spring has more mass when the coils
are compressed than when relaxed.
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14. |
The
classical laws of conservation of energy and conservation of mass do
not need to be modified for relativity.
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Multiple Choice
Identify
the letter of the choice that best completes the statement or answers
the question.
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15. |
You
are in a windowless spacecraft. You need to determine whether your spaceship
is moving at constant nonzero velocity, or is at rest, in an inertial
frame of Earth.
a. |
You
can succeed by making very precise time measurements. |
b. |
You can succeed by making very precise mass measurements. |
c. |
You can succeed by making very precise length and
time measurements. |
d. |
You cannot succeed no matter what you do. |
e. |
You
are in a position not correctly described by any of these propositions. |
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16. |
You
and your friend recede from each other in spacecraft in deep space without
acceleration. In an inertial frame on your spaceship, your friend is
receding at a speed of 0.9999c. If you direct a light beam at
your friend, and your friend directs a light beam at you, then
a. |
neither
beam will reach the ship to which it is directed |
b. |
you will see your friend’s light arrive at
a speed of 2c, and your friend will see your light arrive
at a speed of 2c |
c. |
you
will see your friend’s light arrive at a speed of c,
and your friend will see your light arrive at a speed of c |
d. |
one of you will see light arrive at a speed of
c, and the other will see light arrive at 2c |
e. |
none of these propositions is true |
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17. |
Simultaneity
is
a. |
dilated |
b. |
absolute |
c. |
invariant |
d. |
relative |
e. |
none of these |
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18. |
The
Michelson–Morley experiment established that
a. |
there is no observable ether wind at the surface
of Earth |
b. |
the ether moves at c as Earth travels in
its orbit |
c. |
the ether is an elastic solid that streams over
Earth |
d. |
Earth does not move with respect to the Sun |
e. |
none
of these |
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19. |
A
Klingon spaceship is approaching Earth at approximately 0.8c
measured relative to Earth. The spaceship directs a laser beam forward
directly through your physics classroom window. You measure the speed
of this light to be
a. |
1.8c |
b. |
1.0c |
c. |
0.9c |
d. |
0.8c |
e. |
0.2c |
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20. |
You
are an astronaut heading out toward a star. In the inertial frame of
the star, you are steering directly for the star and are moving at constant
speed. You can determine that you are in motion by
a. |
the
slowing down of on-board clocks |
b. |
the contraction of on-board metre sticks |
c. |
your
increase in mass |
d. |
the
increase in your heart rate |
e. |
none of these |
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21. |
A
clock, designed to tick each second, is moving past you at a uniform
speed. You find the moving clock
to be
a. |
ticking slowly |
b. |
ticking
quickly |
c. |
accurate |
d. |
running backward |
e. |
none
of these |
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22. |
The
proper time between events E1 and E2 is
a. |
the
time measured on clocks at rest with respect to E1
and E2 |
b. |
the
time measured on clocks at rest in an inertial system moving properly
with respect to E1 and E2 |
c. |
the time measured on clocks moving uniformly with
respect to E1 and E2 |
d. |
the time between E1 and E2
as measured by a clock in a national-standards laboratory, such
as the National Research Council in Ottawa |
e. |
none of these |
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23. |
There
are about 2.81 
109 heartbeats in an average lifetime of 72 years. Space
travellers who are born and die on a spaceship moving at a constant
speed of 0.600c can expect their hearts to beat a total of
a. |
(0.600)(2.81
109) times |
b. |
2.81
 109 times |
c. |
(0.800)(2.81 
109) times |
d. |
(1.25)(2.81 
109) times |
e. |
none of these |
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24. |
A
mass–spring system oscillates up and down with a period T
when stationary in the inertial frame of an Earthbound observer. The
same system is then moved past the Earthbound observer, with a velocity
which in the observer’s frame is constant and of magnitude 0.50c.
The observer now determines the period to be
a. |
0.50T |
b. |
0.87T |
c. |
1.0T |
d. |
1.2T |
e. |
2.0T |
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25. |
According
to the effects of length contraction, from the viewpoint of an observer
stationary with respect to a body moving at a uniform speed relative
to the observer,
a. |
the
body is not now contracted but would contract if it were to accelerate |
b. |
the
body contracts along the direction of motion |
c. |
the time it takes for a clock incorporated in the
body to tick contracts |
d. |
the body contracts in some direction transverse
to the direction of its motion |
e. |
none of these |
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26. |
The
energy output of the Sun is 3.7 
1026 J/s. Matter is converted to energy in the Sun at the
rate of
a. |
4.1 
109 kg/s |
b. |
6.3
 109 kg/s |
c. |
7.4 
101 kg/s |
d. |
3.7
 109 kg/s |
e. |
none of these |
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