Question 1

How will you feel in your spacecraft?

Accepted Answer

A) You will be floating weightlessly. 
B) You will feel weight,but less than on Earth. 
C) You will feel weight,but more than on Earth. 
D) You will feel the same weight as you do on Earth. 
E) You will feel yourself pressed against the back of your spaceship with great force,making it difficult to move.

Question 2

Suppose the room in which you are sitting was magically transported off Earth,and sent accelerating through the universe at 9.8 m/s² Assuming your doors and windows are sealed and closed,how could you tell that you'd left Earth?

Accepted Answer

A) You would weigh more than you do on Earth. 
B) You couldn't-the equivalence principle tells us that you won't be able to tell the difference. 
C) Your time would run slower than it does on Earth. 
D) You'd hear a loud whooshing sound as you careened through space.

Question 3

The theory of general relativity proves that wormholes like those used in science fiction cannot exist.

Accepted Answer

A) True 
 B)False

Question 4

Which of the following correctly describes the conditions under which you will feel weightless,according to general relativity?

Accepted Answer

A) any time you are traveling through space at constant speed 
B) any time your worldline is perfectly straight 
C) any time your worldline is following the straightest possible path through spacetime 
D) any time you are very far from any planet 
E) You can never be truly weightless.

Question 5

Why do we see a gravitational redshift in the spectrum of the Sun?

Accepted Answer

A) Time runs slower on the Sun than on Earth,making lines in the solar spectrum have lower frequency and hence longer wavelength than normal. 
B) Gravity makes light heavy,causing it to appear redder. 
C) Because of gravity,the Sun is always moving away from us so we see a redshift. 
D) Spacetime curvature allows red photons of light to escape the Sun more easily than blue photons,leading to an apparent redshift.

Question 6

What are gravitational waves? Have they ever been detected?

Accepted Answer

The answer of What are gravitational waves? Have they ever...

Question 7

Which of the following correctly describes what we mean by a great circle on the surface of Earth?

Accepted Answer

A) any circle on the surface whose center is at the center of Earth 
B) any circle of latitude 
C) any circle on the surface that intersects the equator 
D) any circle larger than 10,000 km in diameter 
E) any circle found on an English farm that happens to have been created by aliens

Question 8

Suppose that a ship is accelerating through space in such a way that the passengers are experiencing a constant force (due to the thrust of the ship)equivalent to the total weight of the ship and passengers on Earth.From the point of view of observers on Earth,how does the ship accelerate?

Accepted Answer

A) It has a constant acceleration of 9.8 m/s²,therefore increasing its speed by 9.8 m/s with each passing second. 
B) At first,it has a nearly constant acceleration of 9.8 m/ s².But as it approaches the speed of light,its acceleration gradually slows in such a way that it never stops accelerating,but never reaches the speed of light either. 
C) At first,it has a very large acceleration-much larger than 9.8 m/s².But when it reaches the speed of light it stops accelerating. 
D) It has a constant acceleration of 9.8 m/s² until it reaches a speed of half the speed of light.Then its acceleration suddenly slows so that it can't go much faster.

Question 9

Which of the following is not a major idea of Einstein's general theory of relativity?

Accepted Answer

A) Time runs slower near strong gravitational fields. 
B) It is possible to travel through wormholes. 
C) Our universe can have no center or boundaries,yet be finite. 
D) Black holes can exist in spacetime,and falling into a black hole means leaving the observable universe.

Question 10

In the text is a photograph that appears to show four identical galaxies arranged as a cross.What are we really seeing?

Accepted Answer

A) four galaxies that are nearly identical because they were born at about the same time 
B) four images of a single background galaxy,created by the gravitational lens of a massive foreground galaxy or cluster 
C) a large galaxy with four central masses that glow brightly 
D) a picture taken with a poorly made telescope,so that a single large object appears as four fuzzy dots

Question 11

According to general relativity,why does Earth orbit the Sun?

Accepted Answer

A) Earth is following the straightest path possible,but spacetime is curved in such a way that this path goes around the Sun. 
B) The mysterious force that we call gravity holds Earth in orbit. 
C) Earth and the Sun are connected by a "ropelike" set of invisible,subatomic particles.

Question 12

What do we mean by the straightest possible path between two points on Earth's surface?

Accepted Answer

A) a path that actually is a perfectly straight line 
B) a path that follows a circle of latitude 
C) a path that follows a circle of longitude 
D) a path that crosses the equator 
E) the shortest path between the two points

Question 13

Imagine that you are sitting in a closed room (no windows,no doors)when,magically,it is lifted from Earth and sent accelerating through space with an acceleration of 1g (9.8 m/s²).According to Einstein's equivalence principle,which of the following is true?

Accepted Answer

A) You won't feel any change and will have no way to know that you've left Earth. 
B) You'll feel a force that will cause your head to repeatedly bang into the ceiling. 
C) You'll know that you left Earth because when you drop a ball it will fall sideways. 
D) You'll know that you left Earth because you'll be floating weightlessly in your room.

Question 14

Einstein's equivalence principle says that

Accepted Answer

A) everyone measures the speed of light to be equivalent. 
B) the effects of gravity are exactly equivalent to the effects of acceleration. 
C) someone traveling at 0.9c will age at the same rate as someone at 0.99c. 
D) all people see themselves at an equivalent distance to the center of the universe.

Question 15

We expect to directly detect gravitational waves in the near future.

Accepted Answer

A) True 
 B)False

Question 16

What do we mean by dimension in the context of relativity?

Accepted Answer

A) the size of an object 
B) the number of independent directions in which movement is possible 
C) the letter used to represent length mathematically 
D) the number of sides that we can see when we look at an object 
E) the height of an object

Question 17

Describe two observational tests that support general relativity.

Accepted Answer

The answer of Describe two observational tests that support general...

Question 18

Suppose two lines appear to be parallel but eventually meet.What type of geometry are you dealing with?

Accepted Answer

A) flat geometry 
B) spherical geometry 
C) saddle-shaped geometry 
D) Euclidean geometry 
E) This situation can never occur.

Question 19

Einstein's general theory of relativity suggests that gravity is

Accepted Answer

A) a force of attraction that acts at a distance between two masses. 
B) caused by curvature of spacetime. 
C) = G × M₁ × M₂/d². 
D) one of four fundamental forces in nature.

Question 20

In special relativity,we learned that people in different reference frames will measure time differently.According to general relativity,why does this happen?

Accepted Answer

A) People in different reference frames experience different realities. 
B) It is an illusion,and time really is the same for everyone. 
C) They have different worldlines. 
D) They are experiencing the same spacetime reality,but from different perspectives.

Exam 27: Spacetime and Gravity