Question 1

The significant result of the Michelson-Morley experiment was that it found:
A)the ether moved with the sun.
B)the ether moved with the Earth.
C)the speed of the ether wind was greater than expected.
D)no effect.

Accepted Answer

The Michelson-Morley experiment found no effect, indicating that the speed of light was constant and did not depend on the motion of the observer, contrary to the prevailing theory of the ether. This result ultimately paved the way for Einstein's development of the theory of relativity.

Question 2

The relativistic effect of time dilation has been verified by which of the following?
A)the discovery of black holes
B)muon experiments
C)twin experiments
D)red shift in distant galaxies

Accepted Answer

Muon experiments have directly observed the time dilation effect predicted by Einstein's theory of relativity. Muons are subatomic particles with a short half-life, but when they are accelerated to high speeds in Earth's atmosphere, they should decay faster due to time dilation. However, experiments have shown that they actually decay slower than expected, confirming the theory. The other options are not directly related to time dilation.

Question 3

Doubling the momentum of:
A)a particle doubles its relativistic total energy.
B)a particle quadruples its relativistic total energy.
C)a photon doubles its relativistic total energy.
D)a photon quadruples its relativistic total energy.

Accepted Answer

Doubling the momentum of a photon doubles its relativistic total energy because both the energy and momentum of a photon are directly proportional to its frequency (or inversely proportional to its wavelength). Therefore, if the momentum is doubled, the energy also doubles, following the relationship E = pc for photons, where E is energy, p is momentum, and c is the speed of light.

Question 4

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?
A)0.45
B)0.71
C)0.82
D)1.4

Accepted Answer

The answer of The observed relativistic length of a super...

Question 5

The period of an oscillating weight on a spring in an inertial frame of reference is 0.80 s.What would be its speed if it were to move by an observer who measures its period as 1.2 s? (c = 3.00 x 10⁸ m/s) A)1.1 x l0⁸m/s B)2.2 x 10⁸ m/s C)2.5 x l0⁸ m/s D)2.9 x 10⁸ m/s

Accepted Answer

The time dilation formula in special relativity is used: T' = T / sqrt(1 - v^2/c^2). Solving for v when T' = 1.2 s and T = 0.80 s gives v ≈ 2.2 x 10^8 m/s.

Question 6

A tuning fork has a frequency of 400 Hz and hence a period of 2.50 x 10^-3s.If the tuning fork is in an inertial frame of reference moving by the observer at speed of 0.750 c,what is the frequency of the fork as measured by the observer? (Assume that measurements are strictly by optical means and that the speed of sound waves in air is not pertinent here). A)265 Hz B)302 Hz C)454 Hz D)605 Hz

Accepted Answer

The correct answer is A because the frequency of the tuning fork as measured by the observer is given by the formula f' = f / (1 - v/c), where f is the frequency of the tuning fork in its own frame of reference, v is the speed of the observer relative to the tuning fork, and c is the speed of light. Plugging in the given values, we get f' = 400 Hz / (1 - 0.750) = 265 Hz.

Question 7

The Michelson-Morley experiment was designed to make use of ________ to find the motion of the Earth relative to the luminiferous ether.
A)sound waves
B)interference fringes
C)electromagnetic wind
D)none of the above

Accepted Answer

The Michelson-Morley experiment utilized interference fringes created by splitting and then recombining light beams to detect the Earth's motion through the supposed luminiferous ether, which was believed to be the medium for light waves.

Question 8

According to the special theory of relativity,if a 30-year old astronaut 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?
A)less than 50 years
B)50 years
C)more than 50 years
D)exactly 100 years

Accepted Answer

According to the special theory of relativity, time dilation occurs at high speeds. This means that time appears to move slower for someone traveling at high speeds compared to someone on earth. Therefore, the astronaut's biological age would be less than 50 years upon returning to earth.

Question 9

I am stationary in a reference system but if my reference system is not an inertial reference system,then,relative to me,a system that is an inertial reference system must:
A)remain at rest.
B)move with constant velocity.
C)be accelerating.
D)be none of the above.

Accepted Answer

The answer of I am stationary in a reference system...

Question 10

The speed of light is equal to: A)5.28 x 10⁷ miles per hour. B)one meter per nanosecond. C)one light-year per year. D)none of the above.

Accepted Answer

The speed of light is measured in meters per second, which is approximately 671 million miles per hour. However, the most commonly used unit for measuring astronomical distances is the light-year, which is the distance that light travels in one year. Therefore, the speed of light is often expressed as one light-year per year, which is equivalent to approximately 5.88 trillion miles per year. Option A is incorrect because the number is made up, and option B is incorrect because one meter per nanosecond is much slower than the speed of light.

Question 11

The experiment that dispelled the idea that light travels in the ether is called the:
A)Michelson-Morley experiment.
B)Hafele and Keating experiment.
C)Fitzgerald-Kennedy experiment.
D)twin paradox.

Accepted Answer

The Michelson-Morley experiment aimed to detect the existence of the ether, a hypothetical medium through which light waves were thought to travel. However, they found no evidence of the ether and this experiment became a critical piece of evidence in developing the theory of special relativity.

Question 12

According to a postulate of Einstein,which of the following describes the nature of the laws of physics as one observes processes taking place in various inertial frames of reference?
A)Laws are same only in inertial frames with zero velocity.
B)Laws are same only in inertial frames moving at low velocities.
C)Laws are same only in inertial frames moving at near speed of light.
D)Laws are same in all inertial frames.

Accepted Answer

According to the principle of relativity, the laws of physics are the same in all inertial frames of reference, regardless of their relative motion. This is one of the fundamental postulates of Einstein's theory of special relativity. Therefore, the correct choice is D - Laws are same in all inertial frames.

Question 13

Which characterizes the main result of the Michelson-Morley experiment?
A)verified the existence of ether
B)involved measuring the speed of sound from a moving source
C)detected no difference in the speed of light regardless of speed of the source relative to observer
D)was designed purposely to verify Einstein's theory of relativity

Accepted Answer

The main result of the Michelson-Morley experiment was that it detected no difference in the measured speed of light regardless of the speed of the source relative to the observer. This result was unexpected and challenged the prevailing theory of the existence of ether. The experiment was not designed to verify Einstein's theory of relativity, as it was conducted before the theory was proposed.

Question 14

A mass is bouncing on the end of a spring with a period T when measured by a ground observer.What would the period of oscillation be (as measured by the same observer)if the mass and spring were moving past the ground observer at a speed of 0.80 c?
A)0.44 T
B)0.60 T
C)1.0 T
D)1.7 T

Accepted Answer

This problem is related to time dilation, a consequence of Einstein's theory of special relativity. The period of the bouncing motion (T) is a proper time interval, which is the time interval measured in the reference frame of the spring and mass. When this system is moving with a relativistic speed v = 0.80c relative to the ground observer, the period will appear longer to the ground observer because of time dilation. The time dilation factor γ can be calculated as follows:

γ = 1/√(1-(v/c)^2) = 1/√(1-0.8^2) = 1/0.6 = 1.67

The period measured by the ground observer (T') can be found by multiplying the proper period by the time dilation factor:

T' = γT = 1.67T

Therefore, the answer is D) 1.7 T.

Question 15

According to the special theory of relativity,which of the following happens to the length of an object,measured in the dimension parallel to the motion of its inertial frame of reference,as the velocity of this frame increases with respect to a stationary observer?
A)length increases
B)length decreases
C)length remains constant
D)length vanishes to zero when velocity equals half speed of light

Accepted Answer

According to the special theory of relativity, as the velocity of an inertial frame of reference increases with respect to a stationary observer, the length of an object measured in the dimension parallel to the motion of the frame of reference decreases. This is known as length contraction. The amount of contraction depends on the velocity of the frame of reference and is given by the Lorentz factor. Therefore, the correct choice is B, length decreases. Choice A is incorrect because length does not increase, but rather it contracts. Choice C is incorrect for the same reason, length does not remain constant. Choice D is incorrect because length does not vanish to zero when velocity equals half the speed of light, but rather it contracts by a certain factor.

Question 16

Einstein's theory of relativity is based in part on which one of the following postulates?
A)Mass and energy are equivalent.
B)Space and time are absolutes.
C)Energy is conserved only in elastic collisions.
D)Speed of light in a vacuum is same for all observers regardless of source velocity.

Accepted Answer

Einstein's theory of relativity is based on two postulates, one of which is that the speed of light in a vacuum is the same for all observers, regardless of their relative motion. This postulate forms the foundation of special relativity and has been experimentally verified multiple times. Choices A, B, and C are incorrect because they either do not relate to the theory of relativity or are not fundamental postulates of the theory.

Question 17

That the speed of light in a vacuum has the same value for all inertial frames is:
A)inconsistent with the results of the Michelson-Morley experiment.
B)consistent with the results of the Michelson-Morley experiment.
C)not related to the results of the Michelson-Morley experiment.
D)not true.

Accepted Answer

The results of the Michelson-Morley experiment showed that the speed of light in a vacuum is constant and does not change with the motion of the observer or the source of light. This is consistent with the principle of relativity, which states that the laws of physics should be the same for all observers in uniform motion relative to each other. Therefore, the fact that the speed of light in a vacuum has the same value for all inertial frames is consistent with the results of the Michelson-Morley experiment.

Question 18

According to the special theory of relativity,which of the following happens to the size of the time interval between two events occurring in an inertial frame of reference as the frame's velocity with respect to the observer increases?
A)interval increases
B)interval decreases
C)interval remains constant
D)interval vanishes to zero when velocity equals half speed of light

Accepted Answer

According to the special theory of relativity, as the velocity of an inertial frame of reference increases with respect to an observer, the observed time interval between two events occurring in that frame (from the perspective of the observer) increases. This phenomenon is known as time dilation.

Question 19

A ground observer measures the period of a pendulum moving as a part of an inertial frame of reference to be 2.30 s as the inertial frame moves by at a velocity of 0.600 c.What would the observed period be of the same pendulum if its inertial frame were at rest with respect to the observer?
A)4.25 s
B)2.07 s
C)3.03 s
D)1.84 s

Accepted Answer

The answer of A ground observer measures the period of...

Question 20

The period of a pendulum is 2.0 s in a stationary inertial frame of reference.What is its period when measured by an observer moving at a speed of 0.60 c with respect to the inertial frame of reference?
A)1.2 s
B)1.6 s
C)2.5 s
D)3.3 s

Accepted Answer

The answer of The period of a pendulum is 2.0...

Quiz 26: Relativity

The significant result of the Michelson-Morley experiment was that it found:

The relativistic effect of time dilation has been verified by which of the following?

Doubling the momentum of:

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?

The period of an oscillating weight on a spring in an inertial frame of reference is 0.80 s.What would be its speed if it were to move by an observer who measures its period as 1.2 s? (c = 3.00 x 10⁸ m/s)

The Michelson-Morley experiment was designed to make use of ________ to find the motion of the Earth relative to the luminiferous ether.

According to the special theory of relativity,if a 30-year old astronaut 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?

I am stationary in a reference system but if my reference system is not an inertial reference system,then,relative to me,a system that is an inertial reference system must:

The speed of light is equal to:

The experiment that dispelled the idea that light travels in the ether is called the:

According to a postulate of Einstein,which of the following describes the nature of the laws of physics as one observes processes taking place in various inertial frames of reference?

Which characterizes the main result of the Michelson-Morley experiment?

A mass is bouncing on the end of a spring with a period T when measured by a ground observer.What would the period of oscillation be (as measured by the same observer) if the mass and spring were moving past the ground observer at a speed of 0.80 c?

According to the special theory of relativity,which of the following happens to the length of an object,measured in the dimension parallel to the motion of its inertial frame of reference,as the velocity of this frame increases with respect to a stationary observer?

Einstein's theory of relativity is based in part on which one of the following postulates?

That the speed of light in a vacuum has the same value for all inertial frames is:

According to the special theory of relativity,which of the following happens to the size of the time interval between two events occurring in an inertial frame of reference as the frame's velocity with respect to the observer increases?

A ground observer measures the period of a pendulum moving as a part of an inertial frame of reference to be 2.30 s as the inertial frame moves by at a velocity of 0.600 c.What would the observed period be of the same pendulum if its inertial frame were at rest with respect to the observer?

The period of a pendulum is 2.0 s in a stationary inertial frame of reference.What is its period when measured by an observer moving at a speed of 0.60 c with respect to the inertial frame of reference?