Question 1

How much mass must be converted to energy to release one million kilowatt-hours?

Accepted Answer

A)  3.6 × 10-6 g 
B)  40 μg 
C)  4.0 g 
D)  3.6 × 10-12 g 
E)  40 pg 
A)  3.6 × 10-6 g 
B)  40 μg 
C)  4.0 g 
D)  3.6 × 10-12 g 
E)  40 pg B

Question 2

A spaceship is observed from the Earth to be moving toward a star at a speed of 0.80 c. If the distance from the spaceship to the star is 1.6 ly as measured from Earth, how far is the star as measured from the moving spaceship?

Accepted Answer

A)  2.7 ly 
B)  1.9 ly 
C)  1.6 ly 
D)  1.2 ly 
E)  0.96 ly 
A)  2.7 ly 
B)  1.9 ly 
C)  1.6 ly 
D)  1.2 ly 
E)  0.96 ly E

Question 3

The expression used for momentum, p=mv,

Accepted Answer

A)  is a good low-velocity approximation. 
B)  is a good high-velocity approximation. 
C)  is correct, provided we properly understand v. 
D)  always gives too high a value for p. 
A)  is a good low-velocity approximation. 
B)  is a good high-velocity approximation. 
C)  is correct, provided we properly understand v. 
D)  always gives too high a value for p. A

Question 4

In a radioactive decay, 2.37 × 10-3 u are converted into kinetic energy. How much kinetic energy is this? (1 u = 1.66 × 10-27 kg)

Accepted Answer

A)  2.13 × 1014 J 
B)  9.31 × 108 J 
C)  3.54 × 10-13 J 
D)  3.93 × 10-30 J 
E)  1.60 × 10-13 J 
A)  2.13 × 1014 J 
B)  9.31 × 108 J 
C)  3.54 × 10-13 J 
D)  3.93 × 10-30 J 
E)  1.60 × 10-13 J

Question 5

A passenger is on a spaceship traveling at 0.8 c. The passenger observes that her watch

Accepted Answer

A)  is running slow. 
B)  is running fast. 
C)  is keeping time as usual. 
D)  is running slow if the ship is traveling in the positive direction. 
E)  is running slow if the ship is traveling in the negative direction. 
A)  is running slow. 
B)  is running fast. 
C)  is keeping time as usual. 
D)  is running slow if the ship is traveling in the positive direction. 
E)  is running slow if the ship is traveling in the negative direction.

Question 6

What is the kinetic energy of a proton moving at 0.800 c? The rest energy of a proton is 938 MeV.

Accepted Answer

A)  1560 MeV 
B)  1250 MeV 
C)  938 MeV 
D)  2500 MeV 
E)  625 MeV 
A)  1560 MeV 
B)  1250 MeV 
C)  938 MeV 
D)  2500 MeV 
E)  625 MeV

Question 7

What is the Lorentz factor γ for a speed of 0.800 c?

Accepted Answer

A)  0.800 
B)  1.67 
C)  0.600 
D)  0.360 
E)  1.25 
A)  0.800 
B)  1.67 
C)  0.600 
D)  0.360 
E)  1.25

Question 8

If the momentum of an electron is 1.53 MeV/c, what is its kinetic energy? The rest energy of an electron is 511 keV.

Accepted Answer

A)  1.53 MeV 
B)  1.02 MeV 
C)  1.44 MeV 
D)  1.10 MeV 
E)  2.59 MeV 
A)  1.53 MeV 
B)  1.02 MeV 
C)  1.44 MeV 
D)  1.10 MeV 
E)  2.59 MeV

Question 9

A spaceship is observed from the Earth to be moving toward a star at a speed of 0.80 c. If the distance from the spaceship to the star is 1.6 ly as measured from Earth, how long does an observer on Earth find that it takes for the spaceship to reach the star?

Accepted Answer

A)  2.0 y 
B)  2.1 y 
C)  1.6 y 
D)  1.2 y 
E)  0.96 y 
A)  2.0 y 
B)  2.1 y 
C)  1.6 y 
D)  1.2 y 
E)  0.96 y

Question 10

What is the rest energy of a proton? (mp = 1.67 × 10-27 kg)

Accepted Answer

A)  1.5 × 10-10 J 
B)  5.0 × 10-13 J 
C)  1.6 × 10-13 J 
D)  1.6 × 10-19 J 
E)  0.0 
A)  1.5 × 10-10 J 
B)  5.0 × 10-13 J 
C)  1.6 × 10-13 J 
D)  1.6 × 10-19 J 
E)  0.0

Question 11

Tritium (3H) decays to 3He releasing 18.6 keV of energy. How much mass is converted into energy during this process?

Accepted Answer

A)  2.07 × 10-13 kg 
B)  2.07 × 10-10 kg 
C)  2.07 × 10-16 kg 
D)  3.31 × 10-29 kg 
E)  3.31 × 10-32 kg 
A)  2.07 × 10-13 kg 
B)  2.07 × 10-10 kg 
C)  2.07 × 10-16 kg 
D)  3.31 × 10-29 kg 
E)  3.31 × 10-32 kg

Question 12

Two cars are traveling down the highway in the same direction. Car A is traveling at 30.0 m/s and car B is passing car A at a relative speed of 3.0 m/s. Using Galilean relativity to calculate the speed of car B relative to the highway results in an answer that is incorrect by how much?

Accepted Answer

A)  3.3 × 10-2 m/s 
B)  3.3 × 10-5 m/s 
C)  3.3 × 10-8 m/s 
D)  3.3 × 10-11 m/s 
E)  3.3 × 10-14 m/s 
A)  3.3 × 10-2 m/s 
B)  3.3 × 10-5 m/s 
C)  3.3 × 10-8 m/s 
D)  3.3 × 10-11 m/s 
E)  3.3 × 10-14 m/s

Question 13

If an object has its speed doubled, what happens to its relativistic momentum?

Accepted Answer

A)  Nothing happens. 
B)  The momentum doubles. 
C)  The momentum halves. 
D)  The momentum more than doubles. 
E)  The momentum increases a little less than double. 
A)  Nothing happens. 
B)  The momentum doubles. 
C)  The momentum halves. 
D)  The momentum more than doubles. 
E)  The momentum increases a little less than double.

Question 14

If a proton has a kinetic energy of 1.000 GeV, what is its momentum? (mp = 938.3 MeV/c2)

Accepted Answer

A)  1.938 GeV/c 
B)  1.000 GeV/c 
C)  938.0 GeV/c 
D)  2.872 GeV/c 
E)  1.696 GeV/c 
A)  1.938 GeV/c 
B)  1.000 GeV/c 
C)  938.0 GeV/c 
D)  2.872 GeV/c 
E)  1.696 GeV/c

Question 15

What error is made calculating the momentum of a particle moving at 0.80 c using classical mechanics rather than relativistic mechanics?

Accepted Answer

A)  less than 1% 
B)  the classical value is 67% too high 
C)  the classical value is 67% too low 
D)  the classical value is 40% too high 
E)  the classical value is 40% too low 
A)  less than 1% 
B)  the classical value is 67% too high 
C)  the classical value is 67% too low 
D)  the classical value is 40% too high 
E)  the classical value is 40% too low

Question 16

If two protons are heading toward one another at 0.800 c in the laboratory frame, what is the kinetic energy of one proton in the frame of reference of the other proton? The mass of a proton is 938 MeV/c2.

Accepted Answer

A)  3.13 GeV 
B)  5.56 GeV 
C)  1.56 GeV 
D)  2.50 GeV 
E)  3.34 GeV 
A)  3.13 GeV 
B)  5.56 GeV 
C)  1.56 GeV 
D)  2.50 GeV 
E)  3.34 GeV

Question 17

A conclusion from special relativity is that events that are simultaneous in one inertial frame

Accepted Answer

A)  are simultaneous in all inertial reference frames. 
B)  are simultaneous in all inertial frames moving at the same speed. 
C)  may not be simultaneous in another inertial reference frame. 
D)  are simultaneous in inertial reference frames moving in the same direction. 
E)  are simultaneous in inertial reference frames moving in the opposite direction. 
A)  are simultaneous in all inertial reference frames. 
B)  are simultaneous in all inertial frames moving at the same speed. 
C)  may not be simultaneous in another inertial reference frame. 
D)  are simultaneous in inertial reference frames moving in the same direction. 
E)  are simultaneous in inertial reference frames moving in the opposite direction.

Question 18

Two observers will always agree on

Accepted Answer

A)  the speed of light. 
B)  the speed of sound. 
C)  the lengths of objects. 
D)  the lifetime of cosmic ray muons. 
A)  the speed of light. 
B)  the speed of sound. 
C)  the lengths of objects. 
D)  the lifetime of cosmic ray muons.

Question 19

Which best describes the proper time interval between two events?

Accepted Answer

A)  the longest interval measured by any inertial observer 
B)  the interval measured in the inertial reference frame in which the two events occur a maximum distance from each other 
C)  the interval measured in an inertial reference frame in which the two events are simultaneous 
D)  the interval measured in an inertial reference frame in which the two events occur at the same place 
E)  None of these choices are correct 
A)  the longest interval measured by any inertial observer 
B)  the interval measured in the inertial reference frame in which the two events occur a maximum distance from each other 
C)  the interval measured in an inertial reference frame in which the two events are simultaneous 
D)  the interval measured in an inertial reference frame in which the two events occur at the same place 
E)  None of these choices are correct

Question 20

A pair of observers moving relative to each other will

Accepted Answer

A)  always agree on the ordering in time of two events 
B)  sometimes disagree about whether two events are simultaneous 
C)  always disagree about the ordering in time of two events 
D)  always agree about whether two events are simultaneous 
A)  always agree on the ordering in time of two events 
B)  sometimes disagree about whether two events are simultaneous 
C)  always disagree about the ordering in time of two events 
D)  always agree about whether two events are simultaneous

Exam 26: Relativity

How much mass must be converted to energy to release one million kilowatt-hours?

A spaceship is observed from the Earth to be moving toward a star at a speed of 0.80 c. If the distance from the spaceship to the star is 1.6 ly as measured from Earth, how far is the star as measured from the moving spaceship?

The expression used for momentum, p=mv,

In a radioactive decay, 2.37 × 10-3 u are converted into kinetic energy. How much kinetic energy is this? (1 u = 1.66 × 10-27 kg)

A passenger is on a spaceship traveling at 0.8 c. The passenger observes that her watch

What is the kinetic energy of a proton moving at 0.800 c? The rest energy of a proton is 938 MeV.

What is the Lorentz factor γ for a speed of 0.800 c?

If the momentum of an electron is 1.53 MeV/c, what is its kinetic energy? The rest energy of an electron is 511 keV.

A spaceship is observed from the Earth to be moving toward a star at a speed of 0.80 c. If the distance from the spaceship to the star is 1.6 ly as measured from Earth, how long does an observer on Earth find that it takes for the spaceship to reach the star?

What is the rest energy of a proton? (mp = 1.67 × 10-27 kg)

Tritium (3H) decays to 3He releasing 18.6 keV of energy. How much mass is converted into energy during this process?

Two cars are traveling down the highway in the same direction. Car A is traveling at 30.0 m/s and car B is passing car A at a relative speed of 3.0 m/s. Using Galilean relativity to calculate the speed of car B relative to the highway results in an answer that is incorrect by how much?

If an object has its speed doubled, what happens to its relativistic momentum?

If a proton has a kinetic energy of 1.000 GeV, what is its momentum? (mp = 938.3 MeV/c2)

What error is made calculating the momentum of a particle moving at 0.80 c using classical mechanics rather than relativistic mechanics?

If two protons are heading toward one another at 0.800 c in the laboratory frame, what is the kinetic energy of one proton in the frame of reference of the other proton? The mass of a proton is 938 MeV/c2.

A conclusion from special relativity is that events that are simultaneous in one inertial frame

Two observers will always agree on

Which best describes the proper time interval between two events?

A pair of observers moving relative to each other will

Introduction

Motion Along a Line

Motion in a Plane

Force and Newtons Laws of Motion

Circular Motion

Conservation of Energy

Linear Momentum

Torque and Angular Momentum

Fluids

Elasticity and Oscillations

Waves

Sound

Temperature and the Ideal Gas

Heat

Thermodynamics

Electric Forces and Fields

Electric Potential

Electric Current and Circuits

Magnetic Forces and Fields

Electromagnetic Induction

Alternating Current

Electromagnetic Waves

Reflection and Refraction of Light

Optical Instruments

Interference and Diffraction

Early Quantum Physics and the Photon

Quantum Physics

Nuclear Physics

Particle Physics

Filters

In a radioactive decay, 2.37 × 10^-3 u are converted into kinetic energy. How much kinetic energy is this? (1 u = 1.66 × 10^-27 kg)

What is the rest energy of a proton? (m_p = 1.67 × 10^-27 kg)

Tritium (³H) decays to ³He releasing 18.6 keV of energy. How much mass is converted into energy during this process?

If a proton has a kinetic energy of 1.000 GeV, what is its momentum? (m_p = 938.3 MeV/c²)

If two protons are heading toward one another at 0.800 c in the laboratory frame, what is the kinetic energy of one proton in the frame of reference of the other proton? The mass of a proton is 938 MeV/c².