Question 1

You are moving at a speed (2/3)c relative to Randy, and Randy shines a light toward you. At what speed do you see the light passing you by?
A) (1/3)c
B) (2/3)c
C) (4/3)c
D) c
E) It depends on whether you are moving towards or away from Randy.

Accepted Answer

According to the theory of relativity, the speed of light in a vacuum is always c, regardless of the relative motion of the source and the observer.

Question 2

A muon at rest decays in 2.2 μs. Moving at 99.% the speed of light, it would be seen to "live" for how long?

Accepted Answer

The answer of A muon at rest decays in 2.2...

Question 3

The atomic bomb that was dropped on Nagasaki in 1945 killed 140,000 people, helping to end World War II on the next day. It released energy equivalent to that of 20,000 tons of TNT explosive. How much mass was converted to energy when this took place? (1000 tons ⇔ 4.3 × 10¹² J) (Incidentally, modern H-bombs have energy yields 1000 times as much!)

Accepted Answer

The answer of The atomic bomb that was dropped on...

Question 4

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

The answer of An alpha particle (6.70 × 10^-27 kg,...

Question 5

A starship is built to plans that state it is to be constructed 100. meters long. It is launched and as it coasts by the Earth, it is seen to be shortened to 5.48 meters long.
(a) How fast is it moving?
(b) The ship's crew measure the length of the ship to be how long?

Accepted Answer

The answer of A starship is built to plans that...

Question 6

Two spaceships approach each other along a straight line at a constant velocity of 0.988c as measured by the captain of one of the ships. An observer on Earth is able to measure the speed of only one of the ships as 0.900c. From the point of view of the observer on Earth, what is the speed of the other ship?

Accepted Answer

The answer of Two spaceships approach each other along a...

Question 7

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 8

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

The answer of A stretch of land is 12.5 km...

Question 9

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

The answer of Consider a student whose mass is 70....

Question 10

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

The answer of You are moving past the Earth at...

Question 11

How fast must something be traveling if its mass increases by 10%?

Accepted Answer

The answer of How fast must something be traveling if...

Question 12

From the Earth, they see the Enterprise approaching at 0.800c and the Klingons approaching from the opposite direction at 0.900c. From the Enterprise, the crew sees the Klingon ship approaching at what speed?

Accepted Answer

The answer of From the Earth, they see the Enterprise...

Question 13

How fast would a rocket ship have to move to contract to half of its proper length (as observed by a stationary object)?

Accepted Answer

The answer of How fast would a rocket ship have...

Question 14

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

The answer of An electron-volt is the energy required to...

Question 15

An electron has a relativistic momentum of 1.1 × 10^-21 kg-m/s. What fraction of its total energy is its kinetic energy?

Accepted Answer

The answer of An electron has a relativistic momentum of...

Question 16

An electron slowing from 0.998c to 0.500c loses how much momentum?
 Express the answer in MeV/c as well as N-s.

Accepted Answer

The answer of An electron slowing from 0.998c to 0.500c...

Question 17

A spaceship carrying a light clock moves at a speed of 0.960c relative to an observer on Earth. Relative to a frame of reference that is fixed with respect to Earth, how long does it take the clock on the ship to advance 1.00 s?
A) 0.960 s
B) 1.22 s
C) 2.59 s
D) 3.57 s
E) 5.83 s

Accepted Answer

The answer of A spaceship carrying a light clock moves...

Question 18

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

The answer of Aliens on Krypton build a spacecraft 472....

Question 19

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...

Question 20

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

Accepted Answer

The answer of Astronaut Rob leaves Earth in a spaceship...

Quiz 29: Relativity

You are moving at a speed (2/3) c relative to Randy, and Randy shines a light toward you. At what speed do you see the light passing you by?

A muon at rest decays in 2.2 μs. Moving at 99.% the speed of light, it would be seen to "live" for how long?

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 starship is built to plans that state it is to be constructed 100. meters long. It is launched and as it coasts by the Earth, it is seen to be shortened to 5.48 meters long. (a) How fast is it moving? (b) The ship's crew measure the length of the ship to be how long?

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?

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?

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?

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?

How fast must something be traveling if its mass increases by 10%?

From the Earth, they see the Enterprise approaching at 0.800c and the Klingons approaching from the opposite direction at 0.900c. From the Enterprise, the crew sees the Klingon ship approaching at what speed?

How fast would a rocket ship have to move to contract to half of its proper length (as observed by a stationary object)?

An electron has a relativistic momentum of 1.1 × 10^-21 kg-m/s. What fraction of its total energy is its kinetic energy?

An electron slowing from 0.998c to 0.500c loses how much momentum? Express the answer in MeV/c as well as N-s.

A spaceship carrying a light clock moves at a speed of 0.960c relative to an observer on Earth. Relative to a frame of reference that is fixed with respect to Earth, how long does it take the clock on the ship to advance 1.00 s?

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?

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?

Quiz 29: Relativity

You are moving at a speed (2/3) c relative to Randy, and Randy shines a light toward you. At what speed do you see the light passing you by?

A muon at rest decays in 2.2 μs. Moving at 99.% the speed of light, it would be seen to "live" for how long?

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 starship is built to plans that state it is to be constructed 100. meters long. It is launched and as it coasts by the Earth, it is seen to be shortened to 5.48 meters long. (a) How fast is it moving? (b) The ship's crew measure the length of the ship to be how long?

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?

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?

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?

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?

How fast must something be traveling if its mass increases by 10%?

From the Earth, they see the Enterprise approaching at 0.800c and the Klingons approaching from the opposite direction at 0.900c. From the Enterprise, the crew sees the Klingon ship approaching at what speed?

How fast would a rocket ship have to move to contract to half of its proper length (as observed by a stationary object)?

An electron has a relativistic momentum of 1.1 × 10-21 kg-m/s. What fraction of its total energy is its kinetic energy?

An electron slowing from 0.998c to 0.500c loses how much momentum? Express the answer in MeV/c as well as N-s.

A spaceship carrying a light clock moves at a speed of 0.960c relative to an observer on Earth. Relative to a frame of reference that is fixed with respect to Earth, how long does it take the clock on the ship to advance 1.00 s?

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?

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?

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)?

An electron has a relativistic momentum of 1.1 × 10^-21 kg-m/s. What fraction of its total energy is its kinetic energy?