Question 1

What speed is required for a length to contract to 80% of its proper length?

Accepted Answer

A)  0.80 c 
B)  0.60 c 
C)  0.40 c 
D)  0.20 c 
E)  0.50 c 
A)  0.80 c 
B)  0.60 c 
C)  0.40 c 
D)  0.20 c 
E)  0.50 c

Question 2

A megaton explosion releases 4.2 × 1015 J of energy. Approximately how much mass is converted into energy in this process?

Accepted Answer

A)  None, if it is the result of a chemical reaction. 
B)  None, since mass is conserved. 
C)  50 kg 
D)  50 g 
E)  109 kg 
A)  None, if it is the result of a chemical reaction. 
B)  None, since mass is conserved. 
C)  50 kg 
D)  50 g 
E)  109 kg

Question 3

If an object increases its speed such that its total energy is doubled, what happens to its relativistic momentum?

Accepted Answer

A)  The momentum is doubled. 
B)  The momentum is more than doubled. 
C)  The momentum is less than doubled. 
D)  The momentum is quadrupled. 
E)  Nothing happens to the momentum. 
A)  The momentum is doubled. 
B)  The momentum is more than doubled. 
C)  The momentum is less than doubled. 
D)  The momentum is quadrupled. 
E)  Nothing happens to the momentum.

Question 4

A spaceship is 25 m wide and 100 m long. When traveling at 0.80 c (in a direction parallel to its length), what is its observed width?

Accepted Answer

A)  42 m 
B)  25 m 
C)  16 m 
D)  15 m 
E)  20 m 
A)  42 m 
B)  25 m 
C)  16 m 
D)  15 m 
E)  20 m

Question 5

What is the momentum of an electron moving at a speed of 0.90 c? (me = 0.511 MeV/c2 = 9.11 × 10-31 kg)

Accepted Answer

A)  3.1 × 10-22 kg·m/s 
B)  2.5 × 10-22 kg·m/s 
C)  5.6 × 10-22 kg·m/s 
D)  4.4 × 10-22 kg·m/s 
E)  2.5 × 10-23 kg·m/s 
A)  3.1 × 10-22 kg·m/s 
B)  2.5 × 10-22 kg·m/s 
C)  5.6 × 10-22 kg·m/s 
D)  4.4 × 10-22 kg·m/s 
E)  2.5 × 10-23 kg·m/s

Question 6

The principle of relativity states that

Accepted Answer

A)  momentum is conserved in all reference frames. 
B)  the Earth is a noninertial reference frame. 
C)  the speed of light in vacuum is constant. 
D)  the laws of physics are the same in all inertial reference frames. 
E)  Newton's second law does not hold at high speeds. 
A)  momentum is conserved in all reference frames. 
B)  the Earth is a noninertial reference frame. 
C)  the speed of light in vacuum is constant. 
D)  the laws of physics are the same in all inertial reference frames. 
E)  Newton's second law does not hold at high speeds.

Question 7

An astronaut in a rocket moving with a speed v = 0.6c relative to Earth performs a collision experiment with two small steel balls and concludes the both momentum and energy are conserved. What would an Earth observer conclude?

Accepted Answer

A)  Only momentum is conserved. 
B)  Only energy is conserved. 
C)  Neither energy nor momentum is conserved. 
D)  Both energy and momentum are conserved. 
E)  The collision never happened because the two balls are never in the same place at the same time. 
A)  Only momentum is conserved. 
B)  Only energy is conserved. 
C)  Neither energy nor momentum is conserved. 
D)  Both energy and momentum are conserved. 
E)  The collision never happened because the two balls are never in the same place at the same time.

Question 8

Which of the following is the best definition of inertial frame?

Accepted Answer

A)  a frame of reference in which Newtonian mechanics holds true, but relativistic mechanics does not 
B)  a frame of reference in which relativistic mechanics holds true, but Newtonian mechanics does not 
C)  a frame of reference in which there are no accelerations without applied forces 
D)  a frame of reference in which Newton's second and third laws hold, but not the first 
E)  None of these choices are correct. 
A)  a frame of reference in which Newtonian mechanics holds true, but relativistic mechanics does not 
B)  a frame of reference in which relativistic mechanics holds true, but Newtonian mechanics does not 
C)  a frame of reference in which there are no accelerations without applied forces 
D)  a frame of reference in which Newton's second and third laws hold, but not the first 
E)  None of these choices are correct.

Question 9

How fast is a particle moving if its kinetic energy is equal to its rest energy?

Accepted Answer

A)  0.00 
B)  0.57 c 
C)  0.75 c 
D)  0.87 c 
E)  0.50 c 
A)  0.00 
B)  0.57 c 
C)  0.75 c 
D)  0.87 c 
E)  0.50 c

What speed is required for a length to contract to 80% of its proper length?

A megaton explosion releases 4.2 × 10¹⁵ J of energy. Approximately how much mass is converted into energy in this process?

If an object increases its speed such that its total energy is doubled, what happens to its relativistic momentum?

A spaceship is 25 m wide and 100 m long. When traveling at 0.80 c (in a direction parallel to its length), what is its observed width?

What is the momentum of an electron moving at a speed of 0.90 c? (m_e = 0.511 MeV/c² = 9.11 × 10^-31 kg)

The principle of relativity states that

An astronaut in a rocket moving with a speed v = 0.6c relative to Earth performs a collision experiment with two small steel balls and concludes the both momentum and energy are conserved. What would an Earth observer conclude?

Which of the following is the best definition of inertial frame?

How fast is a particle moving if its kinetic energy is equal to its rest energy?

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

Exam 26: Relativity

What speed is required for a length to contract to 80% of its proper length?

A megaton explosion releases 4.2 × 1015 J of energy. Approximately how much mass is converted into energy in this process?

If an object increases its speed such that its total energy is doubled, what happens to its relativistic momentum?

A spaceship is 25 m wide and 100 m long. When traveling at 0.80 c (in a direction parallel to its length), what is its observed width?

What is the momentum of an electron moving at a speed of 0.90 c? (me = 0.511 MeV/c2 = 9.11 × 10-31 kg)

The principle of relativity states that

An astronaut in a rocket moving with a speed v = 0.6c relative to Earth performs a collision experiment with two small steel balls and concludes the both momentum and energy are conserved. What would an Earth observer conclude?

Which of the following is the best definition of inertial frame?

How fast is a particle moving if its kinetic energy is equal to its rest energy?

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

A megaton explosion releases 4.2 × 10¹⁵ J of energy. Approximately how much mass is converted into energy in this process?

What is the momentum of an electron moving at a speed of 0.90 c? (m_e = 0.511 MeV/c² = 9.11 × 10^-31 kg)