Question 1

Mort, who is standing on the ground, throws a ball at 20 m/s eastward as measured by him. What is the ball's velocity relative to Velma, who is in a train moving eastward past Mort at 70 m/s?
A) 70 m/s westward
B) 90 m/s westward
C) 50 m/s eastward
D) 50 m/s westward
E) 90 m/s eastward

Accepted Answer

The answer of Mort, who is standing on the ground,...

Question 2

Velma is in a train headed north past Mort at 30 m/s. Velma has a slingshot that can shoot pebbles at 40 m/s. Velma shoots a pebble toward the rear of the train. Mort observes the pebble's velocity to be
A) 10 m/s north.
B) 10 m/s south.
C) 70 m/s south.
D) 70 m/s north.
E) 40 m/s south.

Accepted Answer

The pebble's velocity relative to the train is 40 m/s south, and the train's velocity relative to Mort is 30 m/s north. Therefore, the pebble's velocity relative to Mort is 40 m/s south minus 30 m/s north, resulting in 10 m/s south.

Question 3

During his public school and university days, Einstein could best be described as
A) a nonconforming and daydreaming student.
B) an excellent and hardworking student.
C) a mediocre but hardworking student.
D) a child prodigy who attracted teachers' admiration.
E) a good but not outstanding student.

Accepted Answer

Einstein was known for his nonconformity and often daydreamed, which sometimes led to conflicts with the rigid educational systems he was part of.

Question 4

You are a passenger in a moving car, and you drop a coin from your right hand, holding your left hand directly below the point of release. If the car is moving at unchanging velocity, the coin will come down
A) in your left hand.
B) in front of your left hand.
C) behind your left hand.
D) to the side of your left hand.

Accepted Answer

The coin retains the horizontal velocity of the car when dropped, so it will fall straight down into your left hand.

Question 5

Mort, who is standing on the ground, throws a ball at 20 m/s westward as measured by him. What is the ball's velocity relative to Velma, who is in a train moving eastward past Mort at 70 m/s?
A) 50 m/s westward
B) 50 m/s eastward
C) 90 m/s westward
D) 70 m/s westward
E) 90 m/s eastward

Accepted Answer

The answer of Mort, who is standing on the ground,...

Question 6

If you were to travel at speeds close to the speed of light, you would notice that your
A) mass has increased.
B) body has shortened along the direction of motion.
C) pulse has slowed.
D) All of the above.
E) None of the above.

Accepted Answer

The answer of If you were to travel at speeds...

Question 7

Which of the following processes will increase the mass of the system?
A) A rock is made to move faster and faster.
B) Two magnets that are initially held together by their magnetic forces are separated.
C) Both of the above.
D) A cup of coffee is heated.
E) All of the above.

Accepted Answer

All of the processes listed will increase the mass of the system. When a rock is made to move faster and faster, its mass increases due to the relativistic increase in mass. When two magnets that are initially held together by their magnetic forces are separated, the mass of the system increases due to the energy stored in the magnetic field. When a cup of coffee is heated, the mass of the system increases due to the increase in thermal energy.

Question 8

You lift a 1 kg object [weight on Earth = 10 N] by 1 m. By about how much does the object's mass increase? A) 10^-¹⁶kg B) 10^-¹²kg C) 10^-¹⁴kg D) 0.01 kg E) Its mass doesn't change at all.

Accepted Answer

The mass increase can be calculated using the energy-mass equivalence principle (E=mc²). The energy gained by lifting the object is 10 J (since work done = force x distance = 10 N x 1 m). Using E=mc², the increase in mass m = E/c² = 10 J / (3 x 10⁸ m/s)² ≈ 10⁻¹⁶ kg.

Question 9

Which of the following is a form of matter and not a form of radiation?
A) X- rays
B) the electron beam that creates the picture on a TV tube
C) gamma rays
D) None of the above are forms of radiation.
E) All of the above are forms of radiation.

Accepted Answer

The electron beam is composed of electrons, which are particles of matter, whereas X-rays and gamma rays are forms of electromagnetic radiation.

Quiz 10: The Special Theory of Relativity

Mort, who is standing on the ground, throws a ball at 20 m/s eastward as measured by him. What is the ball's velocity relative to Velma, who is in a train moving eastward past Mort at 70 m/s?

Velma is in a train headed north past Mort at 30 m/s. Velma has a slingshot that can shoot pebbles at 40 m/s. Velma shoots a pebble toward the rear of the train. Mort observes the pebble's velocity to be

During his public school and university days, Einstein could best be described as

You are a passenger in a moving car, and you drop a coin from your right hand, holding your left hand directly below the point of release. If the car is moving at unchanging velocity, the coin will come down

Mort, who is standing on the ground, throws a ball at 20 m/s westward as measured by him. What is the ball's velocity relative to Velma, who is in a train moving eastward past Mort at 70 m/s?

If you were to travel at speeds close to the speed of light, you would notice that your

Which of the following processes will increase the mass of the system?

You lift a 1 kg object [weight on Earth = 10 N] by 1 m. By about how much does the object's mass increase?

Which of the following is a form of matter and not a form of radiation?