Question 1

Momentum: At what speed relative to the lab will a 0.272-kg object have the same momentum as a 1.30-kg object that is moving at 0.515c relative to the lab?

Accepted Answer

A)  0.944c 
B)  0.922c 
C)  0.981c 
D)  0.592c

Question 2

Time dilation: An astronaut in an inertial reference frame measures a time interval Δt between her heartbeats. What will observers in all other inertial reference frames measure for the time interval between her heartbeats?

Accepted Answer

A)  Δt 
B)  more thanΔt 
C)  less than Δt 
D)  The answer depends on whether they are moving toward her or away from her.

Question 3

Time dilation: An astronaut on a spaceship moving at 0.927c says that the trip between two stationary stars took  How long does this journey take as measured by someone at rest relative to the two stars?

Accepted Answer

A)  20.0 y 
B)  2.81 y 
C)  4.05 y 
D)  22.1 y

Question 4

Velocity addition: The captain of spaceship A observes enemy spaceship E escaping with a relative velocity of 0.48c, as shown in the figure. A missile M is fired from ship A, with a velocity of 0.72c relative to ship A. What is the relative velocity of approach of missile M, observed by the crew on ship E?

Accepted Answer

A)  0.37c 
B)  0.24c 
C)  0.34c 
D)  0.30c 
E)  0.27c

Question 5

Velocity addition: Consider three galaxies, Alpha, Beta and Gamma. An observer in Beta sees the other two galaxies each moving away from him in opposite directions at speed 0.70c. At what speed would an observer in Alpha see the galaxy Beta moving?

Accepted Answer

A)  0.82c 
B)  0.70c 
C)  0.94c 
D)  0.35c 
E)  0.57c

Question 6

Total energy: An electron is accelerated from rest through a potential difference of 50.0 kV. What is the TOTAL energy of the electron? (c = 3.00 × 108 m/s, e = 1.60 × 10-19 C, mel = 9.11 × 10-31 kg)

Accepted Answer

A)  8.00 × 10-15 J 
B)  16.2 × 10-15 J 
C)  8.20 × 10-14 J 
D)  9.00 × 10-14 J 
E)  16.2 × 10-14 J

Question 7

Doppler effect: A navigational beacon in deep space broadcasts at a radio frequency of 50 MHz. A spaceship approaches the beacon with a relative velocity of 0.40c. What is the frequency of the beacon radio signal that is detected on the ship?

Accepted Answer

A)  55 MHz 
B)  60 MHz 
C)  66 MHz 
D)  71 MHz 
E)  76 MHz

Question 8

Time dilation: The closest known star to our solar system is Alpha Centauri, which is approximately 4.30 light years away. A spaceship with a constant speed of 0.800c relative to the earth travels from Earth to this star.
(a) How much time would elapse during the trip on a clock on board the spaceship?
(b) How much time would elapse during the trip on a clock on Earth?

Accepted Answer

The answer of Time dilation: The closest known star to...

Question 9

Kinetic energy: How many joules of energy are required to accelerate a 1.0-kg mass from rest to a speed of 86.6% the speed of light? (c = 3.00 × 108 m/s)

Accepted Answer

A)  1.8 × 1017 J 
B)  9.0 × 1016 J 
C)  2.7 × 1012 J 
D)  4.5 × 109 J 
E)  3.0 × 103 J

Question 10

Total energy: During a nuclear reaction, the particles involved lose 4.8 × 10-28 kg of mass. How many joules of energy are released by this reaction? (c = 3.00 × 108 m/s)

Accepted Answer

A)  4.3 × 10-11 J 
B)  1.4 × 10-19 J 
C)  1.6 × 10-36 J 
D)  2.1 × 10-40 J 
E)  5.3 × 10-45 J

Question 11

Length contraction: In their common rest frame, two stars are 90.0 light-years (ly) apart. If they are  apart as measured by the navigator in a spaceship traveling between them, how fast is the spaceship moving? Express your answer in terms of c.

Accepted Answer

A)  0.991c 
B)  0.986c 
C)  0.980c 
D)  0.972c

Exam 29: Electromagnetic Induction

Momentum: At what speed relative to the lab will a 0.272-kg object have the same momentum as a 1.30-kg object that is moving at 0.515c relative to the lab?

Time dilation: An astronaut in an inertial reference frame measures a time interval Δt between her heartbeats. What will observers in all other inertial reference frames measure for the time interval between her heartbeats?

Time dilation: An astronaut on a spaceship moving at 0.927c says that the trip between two stationary stars took How long does this journey take as measured by someone at rest relative to the two stars?

Velocity addition: Consider three galaxies, Alpha, Beta and Gamma. An observer in Beta sees the other two galaxies each moving away from him in opposite directions at speed 0.70c. At what speed would an observer in Alpha see the galaxy Beta moving?

Total energy: An electron is accelerated from rest through a potential difference of 50.0 kV. What is the TOTAL energy of the electron? (c = 3.00 × 10⁸ m/s, e = 1.60 × 10^-19 C, m_el = 9.11 × 10^-31 kg)

Doppler effect: A navigational beacon in deep space broadcasts at a radio frequency of 50 MHz. A spaceship approaches the beacon with a relative velocity of 0.40c. What is the frequency of the beacon radio signal that is detected on the ship?

Kinetic energy: How many joules of energy are required to accelerate a 1.0-kg mass from rest to a speed of 86.6% the speed of light? (c = 3.00 × 10⁸ m/s)

Total energy: During a nuclear reaction, the particles involved lose 4.8 × 10^-28kg of mass. How many joules of energy are released by this reaction? (c = 3.00 × 10⁸ m/s)

Length contraction: In their common rest frame, two stars are 90.0 light-years (ly) apart. If they are apart as measured by the navigator in a spaceship traveling between them, how fast is the spaceship moving? Express your answer in terms of c.