Question 1

The basic difference between the special and general theories of relativity is that

Accepted Answer

The special theory of relativity deals with observers in inertial frames (nonaccelerated), while the general theory of relativity extends the principle to include accelerated frames and incorporates gravity.

Question 2

Velma passes Mort at a high speed. Each holds a meter stick, oriented parallel to the direction of relative motion. Mort observes that

Accepted Answer

According to the theory of relativity, objects in motion relative to an observer appear contracted in the direction of motion. Mort will see Velma's meter stick as shorter than 1 m, while his own meter stick remains 1 m long in his frame of reference.

Question 3

In which of the following processes does the system's total mass change?

Accepted Answer

In both processes, the total mass changes. In the first process, the automobile's mass increases as it speeds up due to the relativistic increase in mass. In the second process, the rubber ball's mass decreases as it is squeezed due to the loss of air.

Question 4

What feature of Einstein's theory of relativity is demonstrated by the phenomenon of matter- antimatter annihilation?

Accepted Answer

Matter-antimatter annihilation demonstrates the conversion of mass into energy, as described by Einstein's equation E = mc², where mass (m) is converted into energy (E).

Question 5

What was Einstein's main reason for proposing the principle of the constancy of lightspeed?

Accepted Answer

Einstein proposed the constancy of the speed of light because he believed that Maxwell's equations, which describe electromagnetism, should hold true in all inertial frames, consistent with the principle of relativity.

Question 6

The meaning of the phrase "space is relative" is that

Accepted Answer

The answer of The meaning of the phrase "space is...

Question 7

Mort stands on Earth. Velma moves away from him in a rocket, at 299,000 km/s (1000 km/s slower than lightspeed). Mort sends a laser beam toward Velma. As the tip of the beam passes her rocket, Velma observes that

Accepted Answer

According to the theory of relativity, the speed of light is constant for all observers, regardless of their relative motion. Therefore, Velma will observe the laser beam moving past her at the speed of light, 300,000 km/s.

Question 8

Velma zooms past Mort at half of lightspeed. Velma observes Mort's clock to run

Accepted Answer

According to the theory of relativity, time dilation occurs when an observer is moving relative to another observer. Velma, moving at half the speed of light, will observe Mort's clock to run slow compared to her own.

Question 9

Is it possible, according to Einstein's relativity, for a child to be biologically older than his or her parents?

Accepted Answer

According to Einstein's theory of relativity, time dilation can occur when traveling at speeds close to the speed of light. If the parents go on a long and fast trip and return to Earth, they would age less than the child who stayed on Earth, making the child biologically older.

Question 10

Velma passes Mort at a high speed. Each holds a meter stick, oriented parallel to the direction of relative motion. Velma observes that

Accepted Answer

According to the theory of relativity, an observer measures their own meter stick as 1 m long, while the meter stick of an object moving relative to them appears contracted (shorter) due to length contraction.

Question 11

Velma, inside a train moving at 20 m/s, throws a rock in the forward direction at 5 m/s. According to her the rock moves at 5 m/s. According to Mort, standing on Earth outside the train, the rock moves at [approximately] 25 m/s. Who is correct?

Accepted Answer

Both Velma and Mort are correct relative to their own reference frames. Velma measures the speed of the rock relative to the train, while Mort measures it relative to the Earth.

Question 12

One way of stating the principle of relativity is:

Accepted Answer

The answer of One way of stating the principle of...

Question 13

In the "special theory of relativity," what does the word "special" refer to?

Accepted Answer

The "special" in the special theory of relativity refers to its restriction to inertial frames of reference, meaning it applies to observers who are not experiencing acceleration.

Question 14

You are inside a jet plane moving at a constant velocity. You toss a rock straight up in the air, and then you keep your hand at the point of release. The rock will come down

Accepted Answer

The rock will come down in your hand because both you and the rock are moving at the same constant velocity as the plane, so the rock maintains its horizontal motion relative to you.

Question 15

In one experiment showing that faster- moving objects have larger masses,

Accepted Answer

The bending of high-speed microscopic particles in electromagnetic fields is used to measure their mass, as the deflection depends on the mass and velocity of the particles.

Question 16

You are in a spaceship moving past Earth at nearly lightspeed and you observe Mort, who is on Earth. You measure his mass, pulse rate, and size. How are they different from the values measured by Mort himself?

Accepted Answer

Due to relativistic effects, Mort's mass appears increased, his pulse rate appears slowed down, and his size appears contracted in the direction of motion from your perspective.

Question 17

Einstein's Relativity seems to say that, if Mort and Velma are twins and Velma goes on a trip and then returns, Velma will then be younger than Mort and Mort will be younger than Velma. What is wrong with this reasoning?

Accepted Answer

The prediction about Velma's observation is not correct because Velma experiences acceleration, which breaks the symmetry of the situation. In the twin paradox, the traveling twin (Velma) undergoes acceleration when turning around to return, which affects her frame of reference and results in her being younger than Mort upon return.

Question 18

Velma passes Mort at a high speed. Velma and Mort each have identical light- clocks. Mort and Velma both observe both clocks to "tick" simultaneously at 12 noon on both clocks. Velma observes that Mort's next tick occurs

Accepted Answer

According to the theory of relativity, Velma, moving at high speed relative to Mort, will observe time dilation. This means Mort's clock ticks slower from Velma's perspective, so Mort's next tick occurs after her own clock ticks.

Question 19

When one kilogram of uranium undergoes nuclear fission,

Accepted Answer

The answer of When one kilogram of uranium undergoes nuclear...

Question 20

If you drop a coin inside a car that is slowing down, the coin will land

Accepted Answer

The answer of If you drop a coin inside a...

Quiz 10: The Special Theory of Relativity