Question 1

A particle has a total energy that is 5 times its rest energy. What is the speed of the particle?

Accepted Answer

A)  0.980c 
B)  0.985c 
C)  0.950c 
D)  0.990c 
E)  0.998c 
A)  0.980c 
B)  0.985c 
C)  0.950c 
D)  0.990c 
E)  0.998c

Question 2

What is meant by proper length?

Accepted Answer

Proper length is the distance

Question 3

A spaceship visits Alpha Centauri and returns to Earth. Alpha Centauri is 4.5 light-years from Earth (our second closest star). The spaceship travels at one-half the speed of light for essentially all of its expedition.
(a) How long was the ship gone according to an observer on the Earth?
(b) How long was the ship gone according to an observer on the spaceship?

Accepted Answer

(a)10.ligh

Question 4

A pion is an unstable particle that has an average lifetime of 2.55 × 10-8 s. This is the time interval between its creation in a nuclear process and its extinction into decay products, as measured in a frame of reference at rest with respect to the pion. An "average" pion is traveling at 0.230c relative to Earth. How far does it travel in its lifetime, relative to Earth?

Accepted Answer

A)  2.07 m 
B)  1.81 m 
C)  2.23 m 
D)  3.22 m 
E)  3.50 m 
A)  2.07 m 
B)  1.81 m 
C)  2.23 m 
D)  3.22 m 
E)  3.50 m

Question 5

State the Equivalence of Physical Laws postulate of special relativity.

Accepted Answer

The laws of physics

Question 6

In a certain chemical reaction, 8.1 × 10-19 J of energy is released per molecule formed. What is the difference in mass per molecule between the sum of the masses of the molecules of the reagents and the mass of the molecules produced by the reaction?

Accepted Answer

A)  8.1 × 10-28 kg 
B)  2.7 × 10-27 kg 
C)  3.2 × 10-27 kg 
D)  5.4 × 10-32 kg 
E)  9.0 × 10-36 kg 
A)  8.1 × 10-28 kg 
B)  2.7 × 10-27 kg 
C)  3.2 × 10-27 kg 
D)  5.4 × 10-32 kg 
E)  9.0 × 10-36 kg

Question 7

You are moving past the Earth at 0.99c and notice your heart beating 88. times/minute.
(a) Your doctor on Earth observes your heart rate to be what?
(b) If you had been moving 99.99% the speed of light, you would have observed your heart to be beating how fast?

Accepted Answer

(a)12.beat

Question 8

A spaceship is going away from Earth with a speed 0.28c. A passenger in the spaceship measures his heartbeat as 72 beats per minute. How many beats per minute are observed in the telemetry radio signals received on Earth? Note that, in addition to time dilation, one must take into account that the signals of successive heartbeats have to travel longer distances because the spaceship is moving away (Doppler Effect).

Accepted Answer

A)  75 
B)  96 
C)  54 
D)  69 
E)  100 
A)  75 
B)  96 
C)  54 
D)  69 
E)  100

Question 9

A spaceship approaches Earth with a speed 0.38c. A passenger in the spaceship measures his heartbeat as 72 beats per minute. How many beats per minute are observed in the telemetry radio signals received on Earth? Note that, in addition to time dilation, one must take into account that the signals of successive heartbeats have to travel shorter distances because the spaceship is moving closer (Doppler Effect).

Accepted Answer

A)  75 
B)  107 
C)  48 
D)  100 
E)  67 
A)  75 
B)  107 
C)  48 
D)  100 
E)  67

Question 10

When a spring is stretched, its mass decreases.

Accepted Answer

A) True 
 B)False

Question 11

Two satellites with equal rest masses of 100 kg are traveling toward each other in deep space. One is traveling at 0.650c and the other at 0.850c. The satellites collide and stick together. What is the rest mass of the combined object after the collision?

Accepted Answer

A)  100 kg 
B)  200 kg 
C)  277 kg 
D)  378 kg 
E)  312 kg 
A)  100 kg 
B)  200 kg 
C)  277 kg 
D)  378 kg 
E)  312 kg

Question 12

According to Einstein's theory of general relativity, a ray of light bends in an accelerated frame of reference.

Accepted Answer

A) True 
 B)False

Question 13

An alpha particle (6.70 × 10-27 kg, 3.2 × 10-19 Coulomb) travels at 0.965c. What is its:
(a) rest energy (in eV)?
(b) total energy (in eV)?
(c) kinetic energy (in eV)?

Accepted Answer

(a)3.76 Ge

Question 14

A muon is an unstable particle that has an average lifetime of 1.52 × 10-6 s. This is the time interval between its creation in a nuclear process and its extinction into decay products, as measured in a frame of reference at rest with respect to the muon. An "average" muon is observed by a scientist on Earth to travel 342 m in its lifetime. What is the speed of the muon relative to Earth?

Accepted Answer

A)  0.821c 
B)  0.681c 
C)  0.601c 
D)  0.551c 
E)  0.335c 
A)  0.821c 
B)  0.681c 
C)  0.601c 
D)  0.551c 
E)  0.335c

Question 15

A one-kilogram aluminum ingot is heated from 0°C to 100°C. By what amount does its mass change? The specific heat of aluminum is 900 J/(kg∙K).

Accepted Answer

A)  Its mass does not change. 
B)  Its mass increases by 0.50 × 10-12 kg. 
C)  Its mass decreases by 0.50 × 10-12 kg. 
D)  Its mass increases by 1.0 × 10-12 kg. 
E)  Its mass decreases by 1.0 × 10-12 kg. 
A)  Its mass does not change. 
B)  Its mass increases by 0.50 × 10-12 kg. 
C)  Its mass decreases by 0.50 × 10-12 kg. 
D)  Its mass increases by 1.0 × 10-12 kg. 
E)  Its mass decreases by 1.0 × 10-12 kg.

Question 16

In order to see a distant star during a total eclipse of the Sun you must look for it in a direction that is farther from the Sun than the direction you would normally look for the star.

Accepted Answer

A) True 
 B)False

Question 17

A space tow barge pushes on a spaceship with a rest mass of 15,000 kg and accelerates it from a speed of 0.600c to a speed of 0.700c. How much work does the tow barge have to do to accomplish this?

Accepted Answer

A)  1.35 × 1020 J 
B)  2.03 × 1020 J 
C)  2.70 × 1020 J 
D)  5.42 × 1020 J 
E)  8.78 × 1019 J 
A)  1.35 × 1020 J 
B)  2.03 × 1020 J 
C)  2.70 × 1020 J 
D)  5.42 × 1020 J 
E)  8.78 × 1019 J

Question 18

Two spaceships approach Earth from the same direction. One has a speed of 0.21c and the other a speed of 0.34c, both relative to Earth. What is the speed of one spaceship relative to the other?

Accepted Answer

A)  0.13c 
B)  0.14c 
C)  0.15c 
D)  0.16c 
E)  0.18c 
A)  0.13c 
B)  0.14c 
C)  0.15c 
D)  0.16c 
E)  0.18c

Question 19

Astronaut Rachel leaves Earth in a spaceship at a speed of 0.960c relative to an observer on Earth. Rachel's destination is a star system 14.4 light-years away (one light-year is the distance light travels in one year). According to Rachel, how long does the trip take?

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 20

A stretch of land is 12.5 km long on a map.
(a) What would be its length to an observer moving by, parallel to the stretch, at 0.95c?
(b) Which length is the proper length?
(c) How fast must the observer move for the land to appear 6.50 km long?

Accepted Answer

(a)3.9 km

Exam 29: Relativity

A particle has a total energy that is 5 times its rest energy. What is the speed of the particle?

What is meant by proper length?

State the Equivalence of Physical Laws postulate of special relativity.

In a certain chemical reaction, 8.1 × 10-19 J of energy is released per molecule formed. What is the difference in mass per molecule between the sum of the masses of the molecules of the reagents and the mass of the molecules produced by the reaction?

You are moving past the Earth at 0.99c and notice your heart beating 88. times/minute. (a) Your doctor on Earth observes your heart rate to be what? (b) If you had been moving 99.99% the speed of light, you would have observed your heart to be beating how fast?

When a spring is stretched, its mass decreases.

Two satellites with equal rest masses of 100 kg are traveling toward each other in deep space. One is traveling at 0.650c and the other at 0.850c. The satellites collide and stick together. What is the rest mass of the combined object after the collision?

According to Einstein's theory of general relativity, a ray of light bends in an accelerated frame of reference.

An alpha particle (6.70 × 10-27 kg, 3.2 × 10-19 Coulomb) travels at 0.965c. What is its: (a) rest energy (in eV)? (b) total energy (in eV)? (c) kinetic energy (in eV)?

A one-kilogram aluminum ingot is heated from 0°C to 100°C. By what amount does its mass change? The specific heat of aluminum is 900 J/(kg∙K).

In order to see a distant star during a total eclipse of the Sun you must look for it in a direction that is farther from the Sun than the direction you would normally look for the star.

A space tow barge pushes on a spaceship with a rest mass of 15,000 kg and accelerates it from a speed of 0.600c to a speed of 0.700c. How much work does the tow barge have to do to accomplish this?

Two spaceships approach Earth from the same direction. One has a speed of 0.21c and the other a speed of 0.34c, both relative to Earth. What is the speed of one spaceship relative to the other?

Astronaut Rachel leaves Earth in a spaceship at a speed of 0.960c relative to an observer on Earth. Rachel's destination is a star system 14.4 light-years away (one light-year is the distance light travels in one year). According to Rachel, how long does the trip take?

A stretch of land is 12.5 km long on a map. (a) What would be its length to an observer moving by, parallel to the stretch, at 0.95c? (b) Which length is the proper length? (c) How fast must the observer move for the land to appear 6.50 km long?

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

In a certain chemical reaction, 8.1 × 10^-19 J of energy is released per molecule formed. What is the difference in mass per molecule between the sum of the masses of the molecules of the reagents and the mass of the molecules produced by the reaction?

An alpha particle (6.70 × 10^-27 kg, 3.2 × 10^-19 Coulomb) travels at 0.965c. What is its: (a) rest energy (in eV)? (b) total energy (in eV)? (c) kinetic energy (in eV)?