Deck 35: Special Theory of Relativity

Question 1

According to the well-known equation,energy equals mass times the speed of light squared

A)mass and energy travel at the speed of light squared.
B)energy is actually mass traveling at the speed of light squared.
C)mass and energy travel at twice the speed of light.
D)mass and energy are related.
E)none of these

Answer 1

mass and energy are related.

Question 2

When a blinking light source moves relative to you,the speed of the light

A)changes but its frequency remains constant.
B)remains constant but its frequency can change.
C)stays the same,as does its frequency.

Answer 2

remains constant but its frequency can change.

Question 3

The stretching out of time due to motion is called time

A)stretching.
B)dilation.
C)contraction.
D)warp.
E)expansion.

Answer 3

dilation.

Question 4

As you recede from a blinking light source,the frequency of its blinking that you observe

A)increases.
B)decreases.
C)stays the same.

Question 5

Compared to clocks in a stationary reference frame,clocks in a moving reference frame run

A)slower.
B)faster.
C)at the same speed.

Question 6

According to the special theory of relativity,events that are simultaneous in one frame of reference

A)are simultaneous in all frames of reference.
B)are not simultaneous in other frames of reference.
C)may or may not be simultaneous in other frames of reference.

Question 7

When an object is pushed to relativistic speeds,its momentum is

A)greater than mv.
B)smaller than mv.
C)equal to mv.

Question 8

According to special relativity,one can travel at increased rates

A)both forward and backward in time.
B)backward in time.
C)only forward in time.

Question 9

The experiments of Michelson and Morley provided evidence that the speed of light is

A)invariant.
B)the same whether its source approaches or recedes.
C)constant.
D)all of these
E)none of these

Question 10

Two lightning bolts are seen to strike two distant locations at the same time.Seen from a different location,the two lightning bolts

A)will also be seen at the same time.
B)will not be seen at the same time.
C)may or may not be seen at the same time.

Question 11

You and a friend share the same spacetime when there is no

A)relative velocity between you.
B)acceleration for either of you.
C)difference in your rate of heartbeats.

Question 12

The ether theory of light propagation is

A)much used.
B)incomplete,but still useful.
C)unexplained.
D)discredited.

Question 13

Suppose the time taken for light to bounce to and fro between the parallel mirrors of a light clock is 1 second,in the frame of reference of the light clock.As seen by another observer moving at high speed at right angles to the to-and-fro motion of the bouncing light,the time taken would be

A)also 1 second.
B)less than 1 second.
C)more than 1 second.

Question 14

As you approach a blinking light source,the frequency you observe

A)increases.
B)decreases.
C)stays the same,

Question 15

According to Einstein's theory of special relativity

A)space and time are aspects of each other.
B)energy and mass are aspects of each other.
C)both of these
D)none of these

Question 16

Clocks on a spaceship moving very fast relative to the Earth run more slowly when viewed from

A)the spaceship.
B)the Earth.
C)both places.
D)neither place.

Question 17

According to the special theory of relativity,all laws of nature are the same in reference frames that

A)accelerate.
B)move in circles.
C)move at constant velocity.
D)oscillate.
E)none of these

Question 18

A woman standing on the ground sees a rocket ship move past her at 95% of the speed of light.Compared to when the rocket is at rest,the woman measures the rocket's length as

A)longer.
B)shorter.
C)the same length.

Question 19

Objects accelerated to relativistic speeds

A)live shorter.
B)grow bigger.
C)both of these
D)neither of these

Question 20

Harry takes a space voyage and returns to find his twin sister has aged more than he has.This is evidence that they have been in different

A)frames of reference.
B)space times.
C)realms of time.
D)all of these
E)none of these

Question 21

An astronaut traveling forward at 0.87c holds a meterstick in spear-like fashion.The astronaut sees the spear's length as

A)0)5 m.
B)0)87 m.
C)1 m.
D)1)25 m.
E)1)5 m.

Question 22

We are actually looking into the past when we look at

A)a distant star.
B)our physics book.
C)actually both of these
D)none of these

Question 23

The length of a meterstick projected like a spear at 0.87c is seen by a person at rest to be

A)0)5 m.
B)0)87 m.
C)1 m.
D)1)25 m.
E)1)5 m.

Question 24

If you were to travel at speeds close to the speed of light,you would notice that your own

A)pulse decreases.
B)shape changes.
C)both of these
D)neither of these

Question 25

As a light source blinking at a steady rate approaches you at an increasing speed (accelerating toward you),the frequency of the flashes

A)increases.
B)decreases.
C)remains the same.

Question 26

Suppose you and your sister travel in space in such a way that you notice a slowing of time for your sister.Your sister will notice that your time runs

A)faster than hers.
B)slower than hers.
C)the same as hers.
D)not enough information given

Question 27

To outside observers,the overall sizes of objects traveling at relativistic speeds are

A)larger.
B)smaller.
C)the same size.

Question 28

According to the special theory of relativity,if you measure your own pulse while traveling at very high speeds,you would notice your pulse rate to

A)increase.
B)decrease.
C)be the same as usual.

Question 29

Compared to standard Earth time,there is a physical slowing of your time when you travel at

A)relativistic speeds.
B)everyday low speeds.
C)both of these
D)none of these

Question 30

Relativity equations for time,length and momentum hold true for

A)relativistic speeds.
B)everyday low speeds.
C)both of these
D)none of these

Question 31

In some reference frame in the universe,you,right now,may be traveling at a speed that is

A)faster than the speed of light.
B)slower than the speed of light.
C)at the speed of light.
D)None of the above choices are correct.

Question 32

Consider a planet at rest and a spaceship that whizzes past the planet at high speed.An observer on the planet sees a contracted spaceship,while an observer on the spaceship sees

A)a contracted planet.
B)an expanded planet.
C)a normal planet.
D)could be contracted or expanded depending on the direction of travel

Question 33

According to relativity theory,if a space trip finds a son or daughter biologically older than his or her parents,then the space trip is taken by the

A)son or daughter.
B)parents.
C)either
D)Neither,it can't be done.

Question 34

The frequency of a blinking light source appears to double as the light source approaches you.As the same light source moves away from you at the same speed,its frequency

A)is halved.
B)is doubled.
C)stays the same.

Question 35

Suppose you look at the huge clock on the Big Ben Tower in London and it reads 12 noon.If you could travel away from the clock at the speed of light and view it with a telescope,it would

A)run slower than usual.
B)run faster than usual.
C)be frozen at 12 noon.

Question 36

Electrons fired in the TV tubes of recent years traveled at about 0.25 times the speed of light,with momentum greater than their mass times 0.25c.Strictly speaking,this

A)increased your electric bill.
B)decreased your electric bill.
C)had no effect on your electric bill.

Question 37

A spaceship that is traveling very fast with respect to your frame of reference,fires a photon beam that travels at speed c with respect to the spaceship.You measure the photon beam's speed to be

A)less than c.
B)more than c.
C)equal to c.

Question 38

Event A occurs before event B in a certain frame of reference.In another frame of reference,event A could occur

A)after event B.
B)simultaneous with event B.
C)either of these
D)neither of these

Question 39

When you approach a blinking light source which in turn is moving towards you,you perceive an increase in

A)both speed and frequency of the light.
B)speed,but not frequency of the light.
C)frequency of the light,but not speed.

Question 40

As you approach a light source,the wavelength of the emitted light appears

A)longer.
B)shorter.
C)the same.

Question 41

Consider a spaceship that moves toward you at half the speed of light.It fires a probe toward you,relative to itself,at 0.7 the speed of light.Relative to you,the probe approaches at about

A)70% c.
B)87% c.
C)89% c.
D)92% c.
E)96% c.

Question 42

Consider a spaceship that moves away from you at half the speed of light.It fires a probe,also away from you,at half the speed of light relative to the spaceship.Relative to you,the probe moves at

A)80% c.
B)87% c.
C)90% c.
D)95% c.
E)100% c.

Question 43

Suppose two spaceships approach each other at the speed of light,and each sends a beam of light to warn the other of its approach.From the frame of reference of either spaceship,the light will reach the other ship

A)before they collide.
B)as they collide.
C)after they collide.

Question 44

If you use the relativistic velocity-addition formula to add everyday velocities,you will get

A)nonsense.
B)a significantly better result than if you add them classically.
C)a result almost identical to the classical result.

Question 45

If a 1-microgram antimatter meteor were to strike the Earth,the amount of energy of forms other than mass that would be produced would be

A)18 joules.
B)18 thousand joules.
C)18 million joules.
D)18 billion joules.
E)180 billion joules.

Question 46

There is an upper limit on the speed of a particle.This means there is also an upper limit on its

A)momentum.
B)kinetic energy.
C)both of these
D)neither of these

Question 47

A heavy meterstick has a mass of 1 kg.When the meterstick is thrown like a spear past you,you measure its momentum to be 2mv.What do you measure its length to be?

A)1 m
B)0)87 m
C)0)5 m
D)0)25 m
E)none of these

Question 48

Suppose a blinking light source uniformly accelerates away from you.As the source gets farther and farther away,you'll notice that the frequency of the flashes

A)increases.
B)decreases.
C)neither increases nor decreases.

Question 49

A 10-meter-long spear is thrown at relativistic speeds through a 10-meter-long pipe.(Both these dimensions are measured when each is at rest. )When the spear passes through the pipe,which of the following statements is true?

A)The spear appears to shrink so the pipe completely covers it.
B)The pipe appears to shrink so the spear extends from both ends.
C)Both appear to shrink equally so the pipe barely covers the spear.
D)any of these,depending on the motion of the observer (moving with the spear,at rest with the pipe,and so on).
E)none of these

Question 50

Radioactive muons formed high in the atmosphere have an average lifetime of 2 millionths of a second and travel toward Earth at nearly the speed of light.They are so high they should have decayed by the time they reach the Earth's surface,according to pre-relativity physics.They don't because they

A)live longer due to time dilation.
B)travel a shorter distance due to length contraction.
C)either of these
D)neither of these