Question 1

If our Sun were to suddenly explode,how long after the explosion would it take observers on Earth to notice?

Accepted Answer

A) 0 s 
B) 10 s 
C) 3 minutes 
D) 5 minutes 
E) 8 minutes 
A) 0 s 
B) 10 s 
C) 3 minutes 
D) 5 minutes 
E) 8 minutes E

Question 2

A new particle is discovered at Stanford Linear Accelerator.If the total energy of the particle is 17.0 GeV and its momentum is 5.00 GeV/c,what is the rest mass of the particle?

Accepted Answer

A) 15.5 GeV/c2 
B) 16.2 GeV/c2 
C) 12.0 GeV/c2 
D) 17.0 GeV/c2 
A) 15.5 GeV/c2 
B) 16.2 GeV/c2 
C) 12.0 GeV/c2 
D) 17.0 GeV/c2 B

Question 3

An astronaut on the space shuttle traveling at a speed of 0.70 c is holding a meter stick parallel to the direction of motion.What is the length of the meter stick as measured by another astronaut on the shuttle?

Accepted Answer

A) 0.74 m 
B) 1.0 m 
C) 1.2 m 
D) .8 m 
E) 2.1 m 
A) 0.74 m 
B) 1.0 m 
C) 1.2 m 
D) .8 m 
E) 2.1 m B

Question 4

A 50-meter spaceship (as measured in the rest frame)is travelling at 0.6c relative to a stationary observer.How long does the spaceship appear to the stationary observer?

Accepted Answer

A) 35 m 
B) 40 m 
C) 45 m 
D) 55 m 
E) 60 m 
A) 35 m 
B) 40 m 
C) 45 m 
D) 55 m 
E) 60 m

Question 5

Suppose a clock at rest measures 20 s for a task.The speed of the clock that would measure 10 s for the same task is

Accepted Answer

A) 0.22 c. 
B) 0.59 c. 
C) 0.69 c. 
D) 0.87 c. 
A) 0.22 c. 
B) 0.59 c. 
C) 0.69 c. 
D) 0.87 c.

Question 6

What is the energy of a particle with speed of 0.8 cand momentum of 10-20 Ns?

Accepted Answer

A) 0.8 * 10-20 J 
B) 3.8 * 10-12 J 
C) 2.4 * 10-13 J 
D) 1.6 * 10-28 J 
A) 0.8 * 10-20 J 
B) 3.8 * 10-12 J 
C) 2.4 * 10-13 J 
D) 1.6 * 10-28 J

Question 7

A laser with wavelength of 633 nm is used to excite a gas of atoms which strongly absorb radiation at 638 nm.Which gas atoms will absorb the laser radiation best?

Accepted Answer

A) An atom that is moving toward the laser at 2.4 * 106 m/s. 
B) An atom that is moving away from the laser at 2.4 * 106 m/s. 
C) An atom that is moving away from the laser at 1.2 * 106 m/s. 
D) An atom that is moving toward the laser at 1.2 * 106 m/s. 
E) An atom that is that is at rest with respect to the laser. 
A) An atom that is moving toward the laser at 2.4 * 106 m/s. 
B) An atom that is moving away from the laser at 2.4 * 106 m/s. 
C) An atom that is moving away from the laser at 1.2 * 106 m/s. 
D) An atom that is moving toward the laser at 1.2 * 106 m/s. 
E) An atom that is that is at rest with respect to the laser.

Question 8

A spacecraft travels along a straight line from the Earth to the Moon a distance of 3.84 * 108 m.Its speed measured on Earth is 0.70 c.How long does the trip take according to a clock on Earth?

Accepted Answer

A) 1.2 s 
B) 1.3 s 
C) 1.5 s 
D) 1.8 s 
A) 1.2 s 
B) 1.3 s 
C) 1.5 s 
D) 1.8 s

Question 9

If an electron (rest mass = 0.511 MeV/c2)has a speed of 99% of that of light,what is its total energy?

Accepted Answer

A) 0.511 MeV 
B) 0.750 MeV 
C) 3.62 MeV 
D) 7.33 MeV 
E) 19.2 MeV 
A) 0.511 MeV 
B) 0.750 MeV 
C) 3.62 MeV 
D) 7.33 MeV 
E) 19.2 MeV

Question 10

Which quantity is invariant,i.e.,has the same value,in all reference frames?

Accepted Answer

A) Time,$\Delta$t 
B) Space,$\Delta$x 
C) Velocity,v 
D) Spacetime interval,[($\Delta$r)2 - c2($\Delta$t)2]1/2 
A) Time,$\Delta$t 
B) Space,$\Delta$x 
C) Velocity,v 
D) Spacetime interval,[($\Delta$r)2 - c2($\Delta$t)2]1/2

Question 11

"Fat Man," the atomic bomb dropped on Nagasaki at the end of World War II released approximately 88 * 1012 J of explosive energy.How much mass was converted into energy in this bomb?

Accepted Answer

A) 0.88 g 
B) 0.98 g 
C) 1.1 g 
D) 2.1 g 
E) 2.9 * 105 kg 
A) 0.88 g 
B) 0.98 g 
C) 1.1 g 
D) 2.1 g 
E) 2.9 * 105 kg

Question 12

Two observers standing upright on their feet,move horizontally past each other and look at each other.The acceleration of both is zero and their relative speed is 0.500 c.Observer one looks at observer two and sees that she looks thinner than she is when she isn't moving.What does observer two see?

Accepted Answer

A) Observer one looks wider than she is when she isn't moving. 
B) Observer one looks thinner than she is when she isn't moving. 
C) Observer one looks the same as when she isn't moving. 
D) Observer one looks like a vertical line with no width. 
A) Observer one looks wider than she is when she isn't moving. 
B) Observer one looks thinner than she is when she isn't moving. 
C) Observer one looks the same as when she isn't moving. 
D) Observer one looks like a vertical line with no width.

Question 13

Two rockets approach each other;each rocket has a speed of 0.65 c in Earth's frame of reference.The speed of one rocket in the other's frame of reference is

Accepted Answer

A) 0.91c. 
B) 0.72 c. 
C) 0.66 c. 
D) 0.54 c. 
A) 0.91c. 
B) 0.72 c. 
C) 0.66 c. 
D) 0.54 c.

Question 14

The rest energy of an electron is 0.511 MeV,and its rest mass is 0.511 MeV/c2. If an electron has a speed of 99% that of light,what fraction of its total energy is in the form of kinetic energy?

Accepted Answer

A) 76% 
B) 50% 
C) 68% 
D) 86% 
A) 76% 
B) 50% 
C) 68% 
D) 86%

Question 15

A rocket ship travels to the Sun (1.51 * 1011 m)in exactly 13 hours.The distance appears to be shortened,from the rocket pilot's point of view,by how much?

Accepted Answer

A) 8730 km 
B) 17,600 km 
C) 8.2 * 105 km 
D) 1.65 * 106 km 
A) 8730 km 
B) 17,600 km 
C) 8.2 * 105 km 
D) 1.65 * 106 km

Question 16

Two observers move past each other and look at each other's clock.The acceleration of both is zero and their relative speed is 0.750 c.Observer one looks at observer two's clock and sees that it's running more slowly than hers.What does observer two see?

Accepted Answer

A) Observer one's clock is running more quickly than her clock. 
B) Observer one's clock is running more slowly than her clock. 
C) Observer one's clock is running at the same rate as her clock. 
D) Observer one's clock has stopped running. 
A) Observer one's clock is running more quickly than her clock. 
B) Observer one's clock is running more slowly than her clock. 
C) Observer one's clock is running at the same rate as her clock. 
D) Observer one's clock has stopped running.

Question 17

The Schwarzschild radius of muon is 2.79 * 10-55 m.What is the mass of a muon?

Accepted Answer

A) 1.88 * 10-28 kg 
B) 9.11 * 10-31 kg 
C) 4.36 * 10-26 kg 
D) 1.67 * 10-27 kg 
E) 2.06 * 10-29 kg 
A) 1.88 * 10-28 kg 
B) 9.11 * 10-31 kg 
C) 4.36 * 10-26 kg 
D) 1.67 * 10-27 kg 
E) 2.06 * 10-29 kg

Question 18

How fast would a 50-meter spaceship (as measured in the rest frame)have to travel to appear 35 meter to a stationary observer?

Accepted Answer

A) 0.25 c 
B) 0.60 c 
C) 0.71 c 
D) 1.0 c 
E) 1.23 c 
A) 0.25 c 
B) 0.60 c 
C) 0.71 c 
D) 1.0 c 
E) 1.23 c

Question 19

A space ship travelling at 55% the speed of light relative to a stationary observer shoots a probe to a receiving ship moving at 65% the speed of light relative to the observer in the same direction.The speed of the probe relative to the first ship is 80% the speed of light.How fast does the receiving ship perceive the speed of the probe to be?

Accepted Answer

A) 0.11 c 
B) 0.23 c 
C) 0.54 c 
D) 0.74 c 
E) 0.89 c 
A) 0.11 c 
B) 0.23 c 
C) 0.54 c 
D) 0.74 c 
E) 0.89 c

Question 20

Right before takeoff,a passenger on a plane flying from town A to town B synchronizes his clock with the clock of his friend waiting for him in town B. The plane flies without interruption at a constant velocity of 285 m/s.The moment the plane touches the ground the two friends check simultaneously the indication of their clocks.The difference between the readings of the clocks B and A is 4.88 ns.Ignoring any effects of acceleration,the clock A of the passenger on the plane indicated that the flight took

Accepted Answer

A) 1.00 h. 
B) 2.00 h. 
C) 3.00 h. 
D) 4.00 h. 
E)  5.00 h. 
A) 1.00 h. 
B) 2.00 h. 
C) 3.00 h. 
D) 4.00 h. 
E)  5.00 h.

Exam 35: Relativity

If our Sun were to suddenly explode,how long after the explosion would it take observers on Earth to notice?

A new particle is discovered at Stanford Linear Accelerator.If the total energy of the particle is 17.0 GeV and its momentum is 5.00 GeV/c,what is the rest mass of the particle?

An astronaut on the space shuttle traveling at a speed of 0.70 c is holding a meter stick parallel to the direction of motion.What is the length of the meter stick as measured by another astronaut on the shuttle?

A 50-meter spaceship (as measured in the rest frame)is travelling at 0.6c relative to a stationary observer.How long does the spaceship appear to the stationary observer?

Suppose a clock at rest measures 20 s for a task.The speed of the clock that would measure 10 s for the same task is

What is the energy of a particle with speed of 0.8 cand momentum of 10-20 Ns?

A laser with wavelength of 633 nm is used to excite a gas of atoms which strongly absorb radiation at 638 nm.Which gas atoms will absorb the laser radiation best?

A spacecraft travels along a straight line from the Earth to the Moon a distance of 3.84 * 108 m.Its speed measured on Earth is 0.70 c.How long does the trip take according to a clock on Earth?

If an electron (rest mass = 0.511 MeV/c2)has a speed of 99% of that of light,what is its total energy?

Which quantity is invariant,i.e.,has the same value,in all reference frames?

"Fat Man," the atomic bomb dropped on Nagasaki at the end of World War II released approximately 88 * 1012 J of explosive energy.How much mass was converted into energy in this bomb?

Two observers standing upright on their feet,move horizontally past each other and look at each other.The acceleration of both is zero and their relative speed is 0.500 c.Observer one looks at observer two and sees that she looks thinner than she is when she isn't moving.What does observer two see?

Two rockets approach each other;each rocket has a speed of 0.65 c in Earth's frame of reference.The speed of one rocket in the other's frame of reference is

The rest energy of an electron is 0.511 MeV,and its rest mass is 0.511 MeV/c2. If an electron has a speed of 99% that of light,what fraction of its total energy is in the form of kinetic energy?

A rocket ship travels to the Sun (1.51 * 1011 m)in exactly 13 hours.The distance appears to be shortened,from the rocket pilot's point of view,by how much?

Two observers move past each other and look at each other's clock.The acceleration of both is zero and their relative speed is 0.750 c.Observer one looks at observer two's clock and sees that it's running more slowly than hers.What does observer two see?

The Schwarzschild radius of muon is 2.79 * 10-55 m.What is the mass of a muon?

How fast would a 50-meter spaceship (as measured in the rest frame)have to travel to appear 35 meter to a stationary observer?

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Filters

What is the energy of a particle with speed of 0.8 cand momentum of 10^-20 Ns?

A spacecraft travels along a straight line from the Earth to the Moon a distance of 3.84 * 10⁸ m.Its speed measured on Earth is 0.70 c.How long does the trip take according to a clock on Earth?

If an electron (rest mass = 0.511 MeV/c²)has a speed of 99% of that of light,what is its total energy?

"Fat Man," the atomic bomb dropped on Nagasaki at the end of World War II released approximately 88 * 10¹² J of explosive energy.How much mass was converted into energy in this bomb?

The rest energy of an electron is 0.511 MeV,and its rest mass is 0.511 MeV/c². If an electron has a speed of 99% that of light,what fraction of its total energy is in the form of kinetic energy?

A rocket ship travels to the Sun (1.51 * 10¹¹ m)in exactly 13 hours.The distance appears to be shortened,from the rocket pilot's point of view,by how much?

The Schwarzschild radius of muon is 2.79 * 10^-55 m.What is the mass of a muon?