Question 1

We can't detect the gravitational redshift coming from the Sun because the Sun has a very small amount of gravity.

Accepted Answer

This statement is false. The Sun has a very strong gravitational pull, and the gravitational redshift can indeed be detected and has been observed in experiments.

Question 2

The singularity of a black hole has an infinitely small radius,but its event horizon is finite.

Accepted Answer

This is a fundamental concept in the physics of black holes. The singularity, which is the point of infinite density at the center of a black hole, has zero physical size or radius. However, the event horizon, which is the boundary beyond which nothing, not even light, can escape the gravitational pull of the black hole, has a finite size determined by its mass and spin.

Question 3

What is the meaning of the phrase inertial frame of reference?
A)a reference frame that is not accelerating
B)a reference frame that is stationary with respect to the Earth
C)a reference frame that is in motion at constant speed
D)a reference frame that is accelerating at a constant rate
E)a reference frame in which there are strong gravitational forces

Accepted Answer

An inertial frame of reference is a reference frame that is not accelerating. In other words, it is a frame of reference in which Newton's first law of motion holds true, and an object in motion will continue in a straight line at a constant speed unless acted upon by a force.

Question 4

Gravitational lensing allows us to see distant objects brightened and distorted because of massive objects in the path that the light from the object travels.

Accepted Answer

Gravitational lensing is a phenomenon in which light from a distant object is bent and magnified as it passes through a massive object, such as a galaxy or a cluster of galaxies, on its way to Earth. This effect can allow astronomers to observe objects that would otherwise be too faint or too small to see. The distortion and brightening of the image is a result of the bending of light caused by the gravitational field of the massive object.

Question 5

You observe a distant galaxy apparently moving away at 1/3 the speed of light (v c/3).If you could measure the speed that this galaxy's light is passing the Earth,you would get:
A)c/3
B)2c/3
C)c
D)4c/3
E)5c/3

Accepted Answer

The speed of light is always constant in vacuum and is independent of the motion of the observer or the source of light. Therefore, the speed at which the light of the distant galaxy is passing the Earth would still be the speed of light, which is denoted by 'c'. The apparent motion of the galaxy away from the Earth is not related to the speed of light.

Question 6

Gravity is nothing more than a curvature in the fabric of spacetime.

Accepted Answer

According to Einstein's theory of general relativity, gravity is the result of a curvature in the fabric of spacetime caused by the presence of massive objects.

Question 7

The mass of an atomic nucleus is a measure of how much energy is contained therein.

Accepted Answer

The mass of an atomic nucleus is related to the amount of energy that can be released through nuclear reactions, as described by Einstein's famous equation E=mc². Therefore, the higher the mass of a nucleus, the more energy is contained within it.

Question 8

One result of relativity is that an astronaut in a windowless spacecraft could tell the difference between falling freely and the presence of a nearby gravitational source.

Accepted Answer

The answer of One result of relativity is that an...

Question 9

You have a 1 kg mass at rest sitting on a lab bench in front of you.You see somebody fly by in a spaceship traveling at 0.2c.That astronaut flying by also has a 1 kg mass sitting on a bench in front of her.She would measure that mass to be 1kg.

Accepted Answer

According to the principle of relativity, all inertial frames of reference are equally valid. Therefore, from the perspective of the astronaut, the mass on her bench would be at rest and would have a mass of 1 kg.

Question 10

Einstein's special theory of relativity implies that if a person standing at the front of a train traveling at 0.1 km/s shines a flashlight out in front of the train,the emitted photons will travel at a speed of 300,000.1 km/s.

Accepted Answer

According to Einstein's special theory of relativity, the speed of light is constant and independent of the motion of the observer. Therefore, the emitted photons will still travel at a speed of 300,000 km/s, regardless of the motion of the train.

Question 11

What will observers in different inertial frames of reference always agree on?
A)how the speed of light varies with the motion of an observer
B)the length of the meter,but not the duration of the second
C)the rate each frame is accelerating
D)the results of physics experiments performed in each frame
E)whether events are simultaneous or not

Accepted Answer

The laws of physics are the same in all inertial frames of reference, so observers in different frames will always agree on the results of physics experiments performed in each frame. They will not always agree on how the speed of light varies with the motion of an observer, the length of the meter or the duration of the second, or whether events are simultaneous or not, as these quantities are affected by relativistic effects. They will also not necessarily agree on the rate each frame is accelerating, as this depends on the local gravitational field in each frame.

Question 12

A black hole can be produced if the stellar core left over after a supernova is larger than 3 M_⨀.

Accepted Answer

This statement is true. If the stellar core left over after a supernova is larger than 3 solar masses (3 MS⨀), it can collapse into a black hole.

Question 13

Black holes emit no light whatsoever.

Accepted Answer

The answer of Black holes emit no light whatsoever....

Question 14

The Sun could turn into a black hole at the end of its life.

Accepted Answer

The Sun is not massive enough to turn into a black hole at the end of its life. Instead, it will transform into a white dwarf.

Question 15

Gamma-ray bursts are probably associated with extremely energetic supernova explosions.

Accepted Answer

Gamma-ray bursts are thought to be associated with supernova explosions, specifically ones that produce a black hole. The energy released in these explosions is believed to be the cause of the intense bursts of gamma radiation.

Question 16

Special relativity says that moving clocks run slower.

Accepted Answer

Special relativity predicts that time dilation occurs when an observer is in relative motion compared to another observer. This means that moving clocks will appear to run slower than stationary clocks.

Question 17

The aberration of starlight is:
A)a change in the wavelength of light caused by the motion of the light source
B)poor focusing of starlight caused by imperfections in the optics of a telescope
C)a change in the direction of starlight caused by its passage through the earth's atmosphere
D)an increase in the wavelength of light as it leaves the surface of a gravitating body
E)a change in the direction of starlight caused by the orbital motion of the Earth

Accepted Answer

The aberration of starlight is a change in the direction of starlight caused by the orbital motion of the Earth. As the Earth moves around the Sun, it is constantly changing its direction relative to the stars, and this causes starlight to appear to come from a slightly different direction than it actually does. This effect was first observed by James Bradley in the 18th century and is known as "stellar aberration".

Question 18

What would happen if mass were continually added to a 2M_⨀ neutron star? A)The star's radius would increase. B)The star could eventually become a black hole. C)The star could erupt as a nova. D)The star could exceed the Chandrasekhar limit and become a Type II supernova. E)The star could eventually return to the top of the main sequence.

Accepted Answer

A neutron star already has a very high mass and density, so continually adding more mass to it would only increase its gravitational attraction. As more and more mass is added, the neutron star could eventually surpass the Tolman–Oppenheimer–Volkoff limit and collapse into a black hole.

Question 19

The Earth orbits the Sun because the Sun changes space around it but not time.

Accepted Answer

The answer of The Earth orbits the Sun because the...

Question 20

Special relativity says that all observers moving at constant speed will measure the same value of the speed of light.

Accepted Answer

This is one of the postulates of special relativity, known as the constancy of the speed of light. It means that no matter how fast or in what direction an observer is moving, they will always measure the speed of light to be the same value, approximately 299,792,458 meters per second.

Quiz 18: Relativity and Black Holes

We can't detect the gravitational redshift coming from the Sun because the Sun has a very small amount of gravity.

The singularity of a black hole has an infinitely small radius,but its event horizon is finite.

What is the meaning of the phrase inertial frame of reference?

Gravitational lensing allows us to see distant objects brightened and distorted because of massive objects in the path that the light from the object travels.

You observe a distant galaxy apparently moving away at 1/3 the speed of light (v c/3) .If you could measure the speed that this galaxy's light is passing the Earth,you would get:

Gravity is nothing more than a curvature in the fabric of spacetime.

The mass of an atomic nucleus is a measure of how much energy is contained therein.

One result of relativity is that an astronaut in a windowless spacecraft could tell the difference between falling freely and the presence of a nearby gravitational source.

You have a 1 kg mass at rest sitting on a lab bench in front of you.You see somebody fly by in a spaceship traveling at 0.2c.That astronaut flying by also has a 1 kg mass sitting on a bench in front of her.She would measure that mass to be 1kg.

Einstein's special theory of relativity implies that if a person standing at the front of a train traveling at 0.1 km/s shines a flashlight out in front of the train,the emitted photons will travel at a speed of 300,000.1 km/s.

What will observers in different inertial frames of reference always agree on?

A black hole can be produced if the stellar core left over after a supernova is larger than 3 M_⨀.

Black holes emit no light whatsoever.

The Sun could turn into a black hole at the end of its life.

Gamma-ray bursts are probably associated with extremely energetic supernova explosions.

Special relativity says that moving clocks run slower.

The aberration of starlight is:

What would happen if mass were continually added to a 2M_⨀ neutron star?

The Earth orbits the Sun because the Sun changes space around it but not time.

Special relativity says that all observers moving at constant speed will measure the same value of the speed of light.

Quiz 18: Relativity and Black Holes

We can't detect the gravitational redshift coming from the Sun because the Sun has a very small amount of gravity.

The singularity of a black hole has an infinitely small radius,but its event horizon is finite.

What is the meaning of the phrase inertial frame of reference?

Gravitational lensing allows us to see distant objects brightened and distorted because of massive objects in the path that the light from the object travels.

You observe a distant galaxy apparently moving away at 1/3 the speed of light (v c/3) .If you could measure the speed that this galaxy's light is passing the Earth,you would get:

Gravity is nothing more than a curvature in the fabric of spacetime.

The mass of an atomic nucleus is a measure of how much energy is contained therein.

One result of relativity is that an astronaut in a windowless spacecraft could tell the difference between falling freely and the presence of a nearby gravitational source.

You have a 1 kg mass at rest sitting on a lab bench in front of you.You see somebody fly by in a spaceship traveling at 0.2c.That astronaut flying by also has a 1 kg mass sitting on a bench in front of her.She would measure that mass to be 1kg.

Einstein's special theory of relativity implies that if a person standing at the front of a train traveling at 0.1 km/s shines a flashlight out in front of the train,the emitted photons will travel at a speed of 300,000.1 km/s.

What will observers in different inertial frames of reference always agree on?

A black hole can be produced if the stellar core left over after a supernova is larger than 3 M⨀.

Black holes emit no light whatsoever.

The Sun could turn into a black hole at the end of its life.

Gamma-ray bursts are probably associated with extremely energetic supernova explosions.

Special relativity says that moving clocks run slower.

The aberration of starlight is:

What would happen if mass were continually added to a 2M⨀ neutron star?

The Earth orbits the Sun because the Sun changes space around it but not time.

Special relativity says that all observers moving at constant speed will measure the same value of the speed of light.

A black hole can be produced if the stellar core left over after a supernova is larger than 3 M_⨀.

What would happen if mass were continually added to a 2M_⨀ neutron star?