Question 1

The laws of physics are the same in all inertial frames of reference.

Accepted Answer

A) True 
 B)False

Question 2

Consider a student whose mass is 70. kg (he weighs 154. lb). If all his mass were converted to energy, this energy could light a 100. watt lamp for how long?

Accepted Answer

6.3 × 10¹⁶ s

Question 3

A particle is moving with a certain speed. Its speed and momentum are being measured with respect to Earth. When the particle's speed doubles, the momentum increases by a factor of 4. What was the original speed of the particle?

Accepted Answer

A)  0.447c 
B)  0.488c 
C)  0.523c 
D)  0.648c 
E)  0.800c 
A)  0.447c 
B)  0.488c 
C)  0.523c 
D)  0.648c 
E)  0.800c

Question 4

You are a passenger on a spaceship. As the speed of the spaceship increases, you would observe

Accepted Answer

A)  your watch slowing down. 
B)  your watch speeding up. 
C)  your watch losing time. 
D)  your watch gaining time. 
E)  nothing unusual about your watch. 
A)  your watch slowing down. 
B)  your watch speeding up. 
C)  your watch losing time. 
D)  your watch gaining time. 
E)  nothing unusual about your watch.

Question 5

In his theory of relativity, Einstein revealed that the behavior we experience at low speeds could not be assumed to hold for high speeds.

Accepted Answer

A) True 
 B)False

Question 6

The first atomic explosion released approximately 1.0 × 1014 J of energy. How much matter had to be changed into energy to produce this yield?

Accepted Answer

A)  1.1 g 
B)  23 g 
C)  13 g 
D)  0.45 kg 
E)  1.1 kg 
A)  1.1 g 
B)  23 g 
C)  13 g 
D)  0.45 kg 
E)  1.1 kg

Question 7

Observers in different inertial frames can disagree about the time separating two events.

Accepted Answer

A) True 
 B)False

Question 8

Two spaceships are traveling through space at velocities of 0.600c and 0.900c, respectively, with respect to Earth. If they are headed directly toward each other, what is their approach velocity, as measured by the captain of either ship?

Accepted Answer

The answer of Two spaceships are traveling through space at...

Question 9

An observer sees two spaceships, S1 and S2, each having the same length in its own rest frame, traveling toward each other along parallel lines from opposite directions, with equal speeds relative to the observer. As seen by this observer, the two spaceships have the same length and, when they are next to each other, the nose of one coincides with the tail of the other, and vice-versa. However, as seen by passengers on either one of the spaceships, the other spaceship is shorter than their own, so if the tail of the other spaceship is in line with the nose of their spaceship, the nose of the other spaceship cannot be lined up with the tail of theirs. How can you explain this discrepancy?

Accepted Answer

Events that are simultaneous in one fram

Question 10

How fast should a moving clock travel if it is to be observed by a stationary observer as running at one-half its normal rate?

Accepted Answer

The answer of How fast should a moving clock travel...

Question 11

An electron-volt is the energy required to move an electron through a potential difference of one volt. Because of the connection between mass and energy, an electron-volt can also be regarded as a unit of mass. What is the equivalent to an electron-volt in kilograms?
 The charge on an electron is 1.602 × 10-19 C.

Accepted Answer

Question 12

A satellite with a rest mass of 200 kg and a speed of 0.800c and a second satellite with a rest mass of 100 kg and a speed of 0.600c are traveling toward each other in deep space. The satellites collide and stick together. What is the speed of the combined object after the collision?

Accepted Answer

A)  0.333c 
B)  0.374c 
C)  0.397c 
D)  0.418c 
E)  0.432c 
A)  0.333c 
B)  0.374c 
C)  0.397c 
D)  0.418c 
E)  0.432c

Question 13

Two spaceships, each 100 m long in its own rest frame, approach Earth from opposite directions, with equal speeds relative to Earth. As measured by a passenger in one of the spaceships, the other spaceship is 96 m long. What is the speed of the spaceships?

Accepted Answer

A)  c/7 
B)  c/6 
C)  c/5 
D)  c/4 
E)  c/3 
A)  c/7 
B)  c/6 
C)  c/5 
D)  c/4 
E)  c/3

Question 14

Aliens on Krypton build a spacecraft 472. teef long. In their units the speed of light is 22.2 million teef/ces. How fast (teef/ces) must it travel to appear to be 66.6 teefs long?

Accepted Answer

0.99c = 22

Question 15

A spaceship enters the solar system moving toward the Sun at a constant speed relative to the Sun. By its own clock, the time elapsed between the time it crosses the orbit of Jupiter and the time it crosses the orbit of Mars is 50.0 minutes. How fast is the spaceship traveling towards the Sun? The radius of the orbit of Jupiter is 778 × 109 m, and that of the orbit of Mars is 228 × 109 m.

Accepted Answer

A)  0.319c 
B)  0.438c 
C)  0.522c 
D)  0.671c 
E)  0.982c 
A)  0.319c 
B)  0.438c 
C)  0.522c 
D)  0.671c 
E)  0.982c

Question 16

Observer A sees a pendulum oscillating back and forth in a relativistic train and measures its period to be TA. Observer B moves together with the train and measures the period of the pendulum to be TB. These two results will be such that

Accepted Answer

A)  TA > TB. 
B)  TA = TB. 
C)  TA B. 
D)  TA could be greater or smaller than TB depending on the direction of the motion. 
A)  TA > TB. 
B)  TA = TB. 
C)  TA B. 
D)  TA could be greater or smaller than TB depending on the direction of the motion.

Question 17

Hydrogen emits light at certain discrete frequencies. One particular emission has a frequency of 4.57 × 1015 s-1, as measured in the frame of reference of the hydrogen atom. Light from this emission is observed coming from a star that is moving away from Earth at 0.900c. What is the observed frequency? Note that, in addition to time dilation, one must take into account that successive wavefronts have to travel longer distances because the star is moving away (Doppler Effect).

Accepted Answer

A)  1.99 × 1015 s-1 
B)  7.62 × 1015 s-1 
C)  1.99 × 1016 s-1 
D)  1.05 × 1015 s-1 
E)  0.90 × 1015 s-1 
A)  1.99 × 1015 s-1 
B)  7.62 × 1015 s-1 
C)  1.99 × 1016 s-1 
D)  1.05 × 1015 s-1 
E)  0.90 × 1015 s-1

Question 18

Astronaut Rob leaves Earth in a spaceship at a speed of 0.960c relative to an observer on Earth. Rob's destination is a star system 14.4 light-years away (one light-year is the distance light travels in one year). Relative to a frame of reference that is fixed with respect to Earth, how long does it take Rob to complete the trip?

Accepted Answer

A)  14.4 years 
B)  15.0 years 
C)  10.8 years 
D)  4.20 years 
E)  22.7 years 
A)  14.4 years 
B)  15.0 years 
C)  10.8 years 
D)  4.20 years 
E)  22.7 years

Question 19

Observers in different inertial frames can disagree about the location of an event.

Accepted Answer

A) True 
 B)False

Question 20

A person in a rocket ship traveling past the earth at a speed of 0.500c fires a laser gun in the forward direction. With what speed does an observer on Earth see the light pulse travel?

Accepted Answer

The answer of A person in a rocket ship traveling...

Exam 29: Relativity

The laws of physics are the same in all inertial frames of reference.

Consider a student whose mass is 70. kg (he weighs 154. lb). If all his mass were converted to energy, this energy could light a 100. watt lamp for how long?

A particle is moving with a certain speed. Its speed and momentum are being measured with respect to Earth. When the particle's speed doubles, the momentum increases by a factor of 4. What was the original speed of the particle?

You are a passenger on a spaceship. As the speed of the spaceship increases, you would observe

In his theory of relativity, Einstein revealed that the behavior we experience at low speeds could not be assumed to hold for high speeds.

The first atomic explosion released approximately 1.0 × 1014 J of energy. How much matter had to be changed into energy to produce this yield?

Observers in different inertial frames can disagree about the time separating two events.

Two spaceships are traveling through space at velocities of 0.600c and 0.900c, respectively, with respect to Earth. If they are headed directly toward each other, what is their approach velocity, as measured by the captain of either ship?

How fast should a moving clock travel if it is to be observed by a stationary observer as running at one-half its normal rate?

A satellite with a rest mass of 200 kg and a speed of 0.800c and a second satellite with a rest mass of 100 kg and a speed of 0.600c are traveling toward each other in deep space. The satellites collide and stick together. What is the speed of the combined object after the collision?

Two spaceships, each 100 m long in its own rest frame, approach Earth from opposite directions, with equal speeds relative to Earth. As measured by a passenger in one of the spaceships, the other spaceship is 96 m long. What is the speed of the spaceships?

Aliens on Krypton build a spacecraft 472. teef long. In their units the speed of light is 22.2 million teef/ces. How fast (teef/ces) must it travel to appear to be 66.6 teefs long?

Observer A sees a pendulum oscillating back and forth in a relativistic train and measures its period to be TA. Observer B moves together with the train and measures the period of the pendulum to be TB. These two results will be such that

Observers in different inertial frames can disagree about the location of an event.

A person in a rocket ship traveling past the earth at a speed of 0.500c fires a laser gun in the forward direction. With what speed does an observer on Earth see the light pulse travel?

Introduction to Physics

One-Dimensional Kinematics

Vectors in Physics

Two-Dimensional Kinematics

Newtons Laws of Motion

Applications of Newtons Laws

Work and Kinetic Energy

Potential Energy and Conservation of Energy

Linear Momentum and Collisions

Rotational Kinematics and Energy

Rotational Dynamics and Static Equilibrium

Gravity

Oscillations About Equilibrium

Waves and Sound

Fluids

Temperature and Heat

Phases and Phase Changes

The Laws of Thermodynamics

Electric Charges, Forces, and Fields

Electric Potential and Electric Potential Energy

Electric Current and Direct-Current Circuits

Magnetism

Magnetic Flux and Faradays Law of Induction

Alternating-Current Circuits

Electromagnetic Waves

Geometrical Optics

Optical Instruments

Physical Optics: Interference and Diffraction

Quantum Physics

Atomic Physics

Nuclear Physics and Nuclear Radiation

Filters

The first atomic explosion released approximately 1.0 × 10¹⁴ J of energy. How much matter had to be changed into energy to produce this yield?

Observer A sees a pendulum oscillating back and forth in a relativistic train and measures its period to be T_A. Observer B moves together with the train and measures the period of the pendulum to be T_B. These two results will be such that