Special Theory Of Relativity MCQ Quiz Questions And Answers
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One of Einstein's postulates in formulating the special theory of relativity was that the laws of physics are the same in reference frames that
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Accelerate.
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Move at constant velocity with respect to an inertial frame.
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Oscillate.
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Are stationary, but not in moving frames.
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Take this special theory of relativity mcq today if you wish to test your knowledge on this fantastic topic! The theory of special relativity is a proven theory in physics regarding the interaction of space, time, and matter. It explains the relationship that is shared by speed, mass, space, and time as well. Have fun while taking this amazing quiz, and don't forget to share it with all your friends once you are done taking it! All the best!
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- 2.
Suppose one twin takes a ride in a spaceship, traveling at a very high speed to a distant star and back again while the other twin remains on Earth. The twin that remained on Earth predicts that the astronaut twin is
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Younger.
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The same age.
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Older.
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Cannot be determined from the given information
Correct Answer
A. Younger.Explanation
According to the theory of relativity, time dilation occurs when an object is moving at a high speed relative to another object. In this scenario, the twin traveling in the spaceship experiences time dilation due to the high speed of the spaceship. As a result, time passes slower for the astronaut twin compared to the twin on Earth. Therefore, when the astronaut twin returns to Earth, they will be younger than the twin who remained on Earth.Rate this question:
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- 3.
The Michelson-Morley experiment was designed to measure
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The relativistic mass of the electron.
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The relativistic energy of the electron.
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The velocity of the Earth relative to the ether.
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The acceleration of gravity on the Earth's surface.
Correct Answer
A. The velocity of the Earth relative to the ether.Explanation
The Michelson-Morley experiment was designed to measure the velocity of the Earth relative to the ether. The experiment aimed to detect the existence of the ether, which was believed to be the medium through which light waves traveled. The experiment involved splitting a beam of light and measuring the time it took for the two beams to travel different paths. If the Earth was moving through the ether, it was expected that the speed of light would vary depending on the direction of the Earth's motion. However, the experiment yielded null results, indicating that the velocity of the Earth relative to the ether was undetectable.Rate this question:
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- 4.
Relative to a stationary observer, a moving object
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Appears shorter than normal.
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Appears longer than normal.
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Keeps its same length time.
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Can do any of the above. It depends on the relative velocity between the observer and the object.
Correct Answer
A. Appears shorter than normal.Explanation
When an object is in motion relative to a stationary observer, it appears shorter than normal. This phenomenon is known as length contraction and is a consequence of the theory of relativity. According to this theory, as an object approaches the speed of light, its length in the direction of motion appears to decrease from the perspective of an observer at rest. This effect is only noticeable at extremely high speeds and is not apparent in everyday situations.Rate this question:
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- 5.
Which of the following depends on the observer's frame of reference?
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The mass of the proton
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The length of a meter stick
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The half-life of a muon
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All of the given answers
Correct Answer
A. All of the given answersExplanation
The correct answer is "all of the given answers". The mass of the proton, the length of a meter stick, and the half-life of a muon all depend on the observer's frame of reference. This means that these quantities can appear different to different observers depending on their relative motion. The concept of frame of reference is a fundamental principle in physics that helps explain how different observers can perceive the same event differently.Rate this question:
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- 6.
The theory of special relativity
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Is based on a complex mathematical analysis.
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Has not been verified by experiment.
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Does not agree with Newtonian mechanics.
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Does not agree with electromagnetic theory.
Correct Answer
A. Does not agree with Newtonian mechanics.Explanation
The theory of special relativity does not agree with Newtonian mechanics. This is because special relativity introduces the concept of spacetime, where space and time are not separate entities but are interconnected. It also includes the principle of the constancy of the speed of light, which contradicts the idea of absolute time and space in Newtonian mechanics. Therefore, the theory of special relativity challenges and modifies the fundamental principles of Newtonian mechanics.Rate this question:
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- 7.
As the speed of a particle approaches the speed of light, the momentum of the particle
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Increases.
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Decreases.
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Remains the same.
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Approaches zero.
Correct Answer
A. Increases.Explanation
As the speed of a particle approaches the speed of light, its momentum increases. This is because momentum is directly proportional to velocity, and as the velocity of the particle increases towards the speed of light, its momentum also increases. This is a consequence of Einstein's theory of relativity, which shows that as an object's velocity approaches the speed of light, its mass increases and therefore its momentum increases as well.Rate this question:
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- 8.
As the speed of a particle approaches the speed of light, the mass of the particle
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Increases.
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Decreases.
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Remains the same.
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Approaches zero.
Correct Answer
A. Increases.Explanation
As the speed of a particle approaches the speed of light, according to Einstein's theory of relativity, the mass of the particle increases. This is known as relativistic mass. As the particle's velocity gets closer to the speed of light, its mass increases exponentially, making it harder to accelerate further. This phenomenon is a fundamental concept in physics and has been experimentally verified.Rate this question:
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- 9.
The length of a spaceship is 10 m when it is at rest. If the spaceship travels by you with a speed of 0.70c, what length does it appear to you?
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5.5 m
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7.1 m
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12 m
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18 m
Correct Answer
A. 7.1 mExplanation
When an object is moving at a high speed relative to an observer, its length appears to be shorter. This phenomenon is known as length contraction. According to the theory of relativity, the length of the spaceship appears shorter to the observer due to its high speed. Therefore, when the spaceship travels by the observer with a speed of 0.70c, it appears to be shorter and its length is perceived as 7.1 m.Rate this question:
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- 10.
Relative to a stationary observer, a moving clock
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Always runs slower than normal.
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Always runs faster than normal.
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Keeps its normal time.
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Can do any of the above. It depends on the relative velocity between the observer and the clock.
Correct Answer
A. Always runs slower than normal.Explanation
According to the theory of relativity, time dilation occurs when an object is moving relative to an observer. This means that a clock moving relative to a stationary observer will appear to run slower than normal. This phenomenon is a result of the time and space being interconnected and affected by the relative motion between objects. Therefore, the correct answer is that a moving clock always runs slower than normal.Rate this question:
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- 11.
An object moves in a direction parallel to its length with a velocity that approaches the velocity of light. The length of this object, as measured by a stationary observer,
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Approaches infinity.
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Approaches zero.
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Increases slightly.
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Does not change.
Correct Answer
A. Approaches zero.Explanation
When an object moves at a velocity close to the speed of light, according to Einstein's theory of relativity, its length appears to contract in the direction of motion. This phenomenon is known as length contraction. As the object's velocity approaches the speed of light, the contraction becomes more significant, causing the length to approach zero. Therefore, the length of the object, as measured by a stationary observer, approaches zero.Rate this question:
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- 12.
A boat can travel 4.0 m/s in still water. With what speed, relative to the shore, does it move in a river that is flowing at 1.0 m/s if the boat is heading straight across the river?
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3.0 m/s
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4.1 m/s
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4.8 m/s
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5.0 m/s
Correct Answer
A. 4.1 m/sExplanation
When a boat is moving across a river, the speed of the boat relative to the shore is the vector sum of the boat's speed in still water and the speed of the river's current. In this case, the boat can travel at 4.0 m/s in still water, and the river is flowing at 1.0 m/s. Since the boat is heading straight across the river, the two velocities can be added together to find the resultant velocity. Using vector addition, the resultant velocity is found to be approximately 4.1 m/s. Therefore, the boat's speed relative to the shore is 4.1 m/s.Rate this question:
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- 13.
What is the speed of a proton if its mass is twice its rest mass?
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0.50c
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0.68c
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0.73c
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0.87c
Correct Answer
A. 0.87cExplanation
If the mass of a proton is twice its rest mass, it means that the proton is moving at a speed close to the speed of light. The speed of light is denoted as 'c' in physics. Among the given options, 0.87c is the closest value to the speed of light. Therefore, the speed of the proton would be approximately 0.87 times the speed of light.Rate this question:
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- 14.
How much energy would be released if 2.0 kg of material was lost during a reaction?
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1.8 * 10^17 J
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1.5 * 10^16 J
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6.0 * 10^8 J
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4.7 * 10^(-8) J
Correct Answer
A. 1.8 * 10^17 J -
- 15.
A spear is thrown by you at a very high speed. As it passes, you measure its length at one-half its normal length. From this measurement, you conclude that the moving spear's mass must be
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One-half its rest mass.
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Twice its rest mass.
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Four times its rest mass.
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None of the given answers
Correct Answer
A. Twice its rest mass.Explanation
When an object is moving at a high speed, according to the theory of special relativity, its length contracts in the direction of motion. This phenomenon is known as length contraction. In this scenario, when the spear is passing by, its length is measured to be one-half its normal length. This implies that the spear is contracted due to its high speed. According to the theory of special relativity, the mass of an object also increases as its speed approaches the speed of light. Therefore, since the length is halved, the mass of the moving spear must be twice its rest mass.Rate this question:
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- 16.
How fast would a rocket ship have to move to contract to half of its proper length (as observed by a stationary object)?
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0.50c
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0.65c
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0.78c
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0.87c
Correct Answer
A. 0.87cExplanation
The correct answer is 0.87c. According to the theory of relativity, as an object approaches the speed of light, its length contracts in the direction of motion. This contraction is known as length contraction. In this question, the rocket ship would have to move at a speed of 0.87 times the speed of light (c) in order to contract to half of its proper length as observed by a stationary object.Rate this question:
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- 17.
The closest star to our solar system is Alpha Centauri, which is 4.30 light years away. A spaceship with a constant speed of 0.800c relative to the Earth travels toward the star. What distance does the space ship travel according to a passenger on the ship?
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2.58 ly
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3.52 ly
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4.12 ly
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4.30 ly
Correct Answer
A. 2.58 lyExplanation
The correct answer is 2.58 ly. According to the theory of relativity, time dilation occurs when an object moves at speeds close to the speed of light. As the spaceship is traveling at a constant speed of 0.800c relative to Earth, time will appear to pass more slowly for the passenger on the ship compared to an observer on Earth. Therefore, the distance traveled by the spaceship, as perceived by the passenger, will be shorter than the actual distance of 4.30 light years. Using the time dilation formula, the distance traveled by the spaceship according to the passenger can be calculated as 4.30 light years multiplied by the Lorentz factor (1/sqrt(1-(v^2/c^2))), where v is the velocity of the spaceship and c is the speed of light. This calculation results in a distance of 2.58 light years.Rate this question:
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- 18.
Michelson and Morley concluded from the results of their experiment that
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The experiment was a failure since there was no detectable shift in the interference pattern.
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The experiment was successful in not detecting a shift in the interference pattern.
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The experiment was a failure since they detected a shift in the interference pattern.
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The experiment was successful in detecting a shift in the interference pattern.
Correct Answer
A. The experiment was a failure since there was no detectable shift in the interference pattern.Explanation
Michelson and Morley concluded that the experiment was a failure since there was no detectable shift in the interference pattern. This means that their experiment did not provide evidence of the existence of the luminiferous ether, which was the medium proposed to carry light waves. The absence of a shift in the interference pattern suggested that the speed of light was constant in all directions, contradicting the prevailing theory at the time. This result had significant implications for the understanding of the nature of light and the development of the theory of relativity.Rate this question:
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- 19.
A boat can travel 4.0 m/s in still water. With what speed, relative to the shore, does it move in a river that is flowing at 1.0 m/s if the boat is heading upstream?
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3.0 m/s
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4.1 m/s
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4.8 m/s
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5.0 m/s
Correct Answer
A. 3.0 m/sExplanation
When a boat is moving upstream, it is moving against the current of the river. This means that the effective speed of the boat is the difference between its speed in still water and the speed of the river current. In this case, the boat can travel at 4.0 m/s in still water, and the river is flowing at 1.0 m/s. Therefore, the speed of the boat relative to the shore when heading upstream is 4.0 m/s - 1.0 m/s = 3.0 m/s.Rate this question:
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- 20.
One 20-year-old twin brother takes a space trip with a speed of 0.80c for 30 years according to a clock on the spaceship. Upon returning to the Earth, what is his own age and the age of the Earth-based twin brother?
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20; 30
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30; 50
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50; 70
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70; 90
Correct Answer
A. 50; 70Explanation
The correct answer is 50; 70. According to the theory of relativity, time dilation occurs when an object is moving at a high velocity relative to another object. In this case, the twin brother who takes the space trip experiences time dilation due to his high velocity. The spaceship's clock shows that 30 years have passed, but from the perspective of the Earth-based twin brother, 50 years have passed. Therefore, the space-traveling twin brother's own age is 50, while the Earth-based twin brother's age is 70.Rate this question:
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- 21.
During a reaction, an element loses 4.8 * 10^(-28) kg of mass. How much energy (in Joules) is released?
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4.3 * 10^(-11) J
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1.4 * 10^(-19) J
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1.6 * 10^(-36) J
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5.3 * 10^(-45) J
Correct Answer
A. 4.3 * 10^(-11) JExplanation
When an element loses mass during a reaction, it is undergoing a process known as nuclear decay. This process releases energy in the form of radiation. The amount of energy released can be calculated using Einstein's famous equation, E=mc^2, where E is the energy, m is the mass lost, and c is the speed of light. In this case, the mass lost is 4.8 * 10^(-28) kg. Plugging this value into the equation, we can calculate the energy released to be 4.3 * 10^(-11) J.Rate this question:
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- 22.
A fast spaceship is traveling with a speed of 0.80c. How fast would light travel from the headlights of the ship relative to a stationary observer?
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0.20c
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0.80c
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1.0c
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1.8c
Correct Answer
A. 1.0cExplanation
When an object is traveling at a significant fraction of the speed of light, the velocity of light emitted from the object remains constant relative to all observers. This means that regardless of the speed of the spaceship, the light from its headlights would still travel at the speed of light, which is 1.0c.Rate this question:
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- 23.
A boat can travel 4.0 m/s in still water. With what speed, relative to the shore, does it move in a river that is flowing at 1.0 m/s if the boat is heading downstream?
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3.0 m/s
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4.1 m/s
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4.8 m/s
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5.0 m/s
Correct Answer
A. 5.0 m/sExplanation
When a boat is moving downstream in a river, the speed of the boat relative to the shore is the sum of the speed of the boat in still water and the speed of the river current. In this case, the boat can travel 4.0 m/s in still water and the river is flowing at 1.0 m/s. Therefore, the speed of the boat relative to the shore will be 4.0 m/s + 1.0 m/s = 5.0 m/s.Rate this question:
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- 24.
A meter stick is moving toward you with a speed of 0.80c. What is its length?
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Zero
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0.40 m
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0.60 m
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1.0 m
Correct Answer
A. 0.60 mExplanation
According to special relativity, as an object approaches the speed of light, its length in the direction of motion appears to contract from the perspective of an observer at rest. This phenomenon is known as length contraction. In this scenario, the meter stick is moving towards the observer with a speed of 0.80c, which is 80% of the speed of light. Therefore, its length will appear to be contracted by a factor of 0.60 (1 - 0.80), resulting in a length of 0.60 m.Rate this question:
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- 25.
The closest star to our solar system is Alpha Centauri, which is 4.30 light years away. A spaceship with a constant speed of 0.800c relative to the Earth travels toward the star. How much time would elapse on a clock on board the spaceship?
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3.23 y
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4.40 y
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5.15 y
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5.38 y
Correct Answer
A. 3.23 yExplanation
The time dilation formula from special relativity can be used to solve this problem. The formula states that time dilation occurs when an object is moving at a significant fraction of the speed of light. The formula is given by t' = t / sqrt(1 - v^2/c^2), where t' is the time experienced by the moving object, t is the time experienced by a stationary observer, v is the velocity of the moving object, and c is the speed of light. In this case, the velocity of the spaceship is given as 0.800c. Plugging this value into the formula, we get t' = t / sqrt(1 - (0.800c)^2/c^2). Simplifying this equation gives t' = t / sqrt(1 - 0.64) = t / sqrt(0.36) = t / 0.6. Since the distance to Alpha Centauri is 4.30 light years, the time experienced by the spaceship is 4.30 light years / 0.6 = 7.17 years. However, this time is experienced by a stationary observer, so the time experienced by the clock on board the spaceship is 7.17 years / 2 = 3.23 years. Therefore, the answer is 3.23 y.Rate this question:
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- 26.
An electron is traveling at 0.85c. What is its mass? (The rest mass is 9.11 * 10^(-31) kg.)
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1.4 * 10^(-29) kg
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7.2 * 10^(-30) kg
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1.7 * 10^(-30) kg
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2.4 * 10^(-30) kg
Correct Answer
A. 1.7 * 10^(-30) kgExplanation
When an object is moving at high speeds, its mass increases due to relativistic effects. This phenomenon is described by the theory of special relativity. The equation for calculating the relativistic mass is given by m = γ * m0, where m is the relativistic mass, m0 is the rest mass, and γ is the Lorentz factor. In this question, the Lorentz factor can be calculated using the equation γ = 1 / sqrt(1 - v^2/c^2), where v is the velocity of the electron and c is the speed of light. Plugging in the values, we find γ = 1.732. Multiplying this by the rest mass, we get the relativistic mass of the electron as 1.7 * 10^(-30) kg.Rate this question:
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- 27.
What happens to the total relativistic energy of a speedy proton when its relativistic mass doubles?
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It doubles.
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It more than doubles.
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It less than doubles.
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It must increase, but it is impossible to say by how much.
Correct Answer
A. It doubles.Explanation
When the relativistic mass of a speedy proton doubles, its total relativistic energy also doubles. This is because the total relativistic energy of an object is directly proportional to its relativistic mass. Therefore, if the mass doubles, the energy will also double.Rate this question:
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- 28.
During a reaction, 1.7 * 10^(-4) J of energy is released. What change of mass would cause this?
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5.1 * 10^(-4) kg
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1.5 * 10^(-13) kg
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4.8 * 10^(-18) kg
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1.9 * 10^(-21) kg
Correct Answer
A. 1.9 * 10^(-21) kgExplanation
The relationship between energy and mass is given by Einstein's famous equation E = mc^2, where E is the energy released, m is the change in mass, and c is the speed of light. Rearranging the equation, we have m = E / c^2. Plugging in the given values, we get m = (1.7 * 10^(-4) J) / (3 * 10^8 m/s)^2 = 1.9 * 10^(-21) kg. Therefore, a change in mass of 1.9 * 10^(-21) kg would cause the given amount of energy to be released.Rate this question:
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- 29.
You are in a rocket traveling away from the Sun at 0.95c. You measure the speed of light from the Sun to be
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0.05c.
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0.95c.
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1.0c.
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Cannot be determined without knowing the frequency of the light
Correct Answer
A. 1.0c.Explanation
The speed of light is always constant in a vacuum, regardless of the motion of the source or observer. This is a fundamental principle of special relativity. Therefore, even though the rocket is moving away from the Sun at 0.95c, the speed of light from the Sun will still be measured as 1.0c.Rate this question:
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- 30.
A spaceship takes a nonstop journey to a planet and returns in 10 hours according to a clock on the spaceship. If the speed of the spaceship is 0.80c, how much time has elapsed on the Earth?
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3.2 h
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7.0 h
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15 h
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17 h
Correct Answer
A. 17 hExplanation
The spaceship is traveling at a speed of 0.80c, which means it is traveling at 80% of the speed of light. According to the theory of relativity, time dilation occurs when an object is moving at high speeds relative to another object. This means that time moves slower for the spaceship compared to Earth. Since the spaceship takes 10 hours according to its own clock, more time has actually passed on Earth. To calculate the elapsed time on Earth, we can use the formula for time dilation: t' = t / √(1 - v^2/c^2), where t' is the time on Earth, t is the time on the spaceship, v is the velocity of the spaceship, and c is the speed of light. Plugging in the values, we get t' = 10 / √(1 - (0.80c)^2/c^2) = 10 / √(1 - 0.64) = 10 / √(0.36) = 10 / 0.6 = 16.67 hours. Rounded to the nearest hour, the elapsed time on Earth is 17 hours.Rate this question:
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- 31.
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 of TNT = 4.3 * 10^12 J) Incidentally, modern H-bombs have energy yields 1000 times as much!
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1 g
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10 g
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100 g
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1 kg
Correct Answer
A. 1 gExplanation
When the atomic bomb was dropped on Nagasaki, it released energy equivalent to that of 20,000 tons of TNT explosive. Given that 1000 tons of TNT is equal to 4.3 * 10^12 J, we can calculate the energy released by the atomic bomb. By dividing the energy released by the conversion factor, we can determine the mass that was converted to energy. In this case, the mass converted to energy is 1 gram.Rate this question:
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- 32.
You are riding in a spaceship that has no windows, radios, or other means for you to observe or measure what is outside. You wish to determine if the ship is stopped or moving at constant velocity. What should you do?
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You can determine if the ship is moving by determining the apparent velocity of light.
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You can determine if the ship is moving by checking your precision time piece. If it's running slow, the ship is moving.
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You can determine if the ship is moving either by determining the apparent velocity of light or by checking your precision time piece. If it's running slow, the ship is moving.
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You should give up because you have taken on an impossible task.
Correct Answer
A. You should give up because you have taken on an impossible task.Explanation
Since the spaceship has no windows, radios, or other means to observe or measure the outside, there is no way to determine if the ship is stopped or moving at a constant velocity. Without any external reference points or measurements, it is impossible to determine the motion of the spaceship.Rate this question:
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- 33.
If the velocity of your spaceship goes from 0.3 c to 0.6 c, then your mass will increase by
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19%.
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38%.
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100%.
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200%.
Correct Answer
A. 19%.Explanation
When an object moves at speeds close to the speed of light (c), its mass increases according to the theory of relativity. This increase in mass is given by the equation: mass = mass0 / sqrt(1 - (v^2/c^2)), where mass0 is the rest mass of the object, v is the velocity of the object, and c is the speed of light. In this case, the initial velocity is 0.3c and the final velocity is 0.6c. Plugging these values into the equation, we find that the mass increases by approximately 19%.Rate this question:
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- 34.
The kinetic energy of a proton is 80% of its total energy. What is the speed of the proton?
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0.02c
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0.87c
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0.98c
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1.0c
Correct Answer
A. 0.98cExplanation
The speed of the proton is 0.98c because kinetic energy is directly proportional to the square of the speed. Since the kinetic energy is given as 80% of the total energy, we can infer that the speed of the proton is 0.98 times the speed of light (c).Rate this question:
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- 35.
An electron is accelerated through 100 kV. By what factor has its mass increased with respect to its rest mass?
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1.20
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1.55
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4.25
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8.00
Correct Answer
A. 1.20Explanation
When an electron is accelerated through a voltage of 100 kV, its mass increases due to relativistic effects. This increase in mass is described by the equation m = m0 / √(1 - (v^2 / c^2)), where m0 is the rest mass of the electron, v is its velocity, and c is the speed of light. Since the electron is accelerated to a high velocity, close to the speed of light, the denominator of the equation becomes very close to 1, resulting in a small increase in mass. Therefore, the factor by which the mass has increased is approximately 1.20.Rate this question:
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- 36.
If you were to measure your pulse rate while in a spaceship moving away from the Sun at a speed close to the speed of light, you would find that it was
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Much faster than normal.
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Much slower than normal.
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The same as it was here on Earth.
Correct Answer
A. The same as it was here on Earth.Explanation
The pulse rate is determined by the heart's ability to pump blood and the body's need for oxygen. The speed at which the spaceship is moving away from the Sun does not directly affect these factors. Therefore, the pulse rate would remain the same as it was on Earth.Rate this question:
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- 37.
Consider two spaceships, each traveling at 0.50c in a straight line. Ship A is moving directly away from the Sun and ship B is approaching the Sun. The science officers on each ship measure the velocity of light coming from the Sun. What do they measure for this velocity?
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Ship A measures it as less than c, and ship B measures it as greater than c.
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Ship B measures it as less than c, and ship A measures it as greater than c.
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On both ships it is measured to be less than c.
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On both ships it is measured to be exactly c.
Correct Answer
A. On both ships it is measured to be exactly c.Explanation
When two objects are moving relative to each other, the speed of light remains constant for all observers, regardless of their motion. This is one of the fundamental principles of special relativity. Therefore, both ships A and B will measure the velocity of light coming from the Sun to be exactly c, the speed of light in a vacuum.Rate this question:
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- 38.
A set of twins, Andrea and Courtney, are initially 10 years old. While Courtney remains on Earth, Andrea rides on a space ship which travels away from Earth at a speed of 0.6c for five years (as measured by Courtney), then turns around and comes back at 0.6c. When Andrea returns, Courtney is 20 years old. How old is Andrea upon her return?
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10 years
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12 years
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18 years
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20 years
Correct Answer
A. 18 yearsExplanation
Andrea experiences time dilation due to her high velocity during her space travel. According to the theory of relativity, time slows down for objects moving at high speeds relative to an observer. As a result, while Andrea is traveling at 0.6c, time passes slower for her compared to Courtney on Earth. Therefore, when Andrea returns after five years (as measured by Courtney), more time has passed for Courtney on Earth. Since Courtney is 20 years old when Andrea returns, Andrea would be younger than her. Considering the time dilation effect, Andrea would be 18 years old upon her return.Rate this question:
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- 39.
An object moves in a direction parallel to its length with a velocity that approaches the velocity of light. The width of this object, as measured by a stationary observer,
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Approaches infinity.
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Approaches zero.
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Increases slightly.
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Does not change.
Correct Answer
A. Does not change.Explanation
When an object moves in a direction parallel to its length with a velocity approaching the velocity of light, according to the theory of relativity, its length contracts in the direction of motion. However, the width of the object, which is perpendicular to the direction of motion, remains unchanged. Therefore, as measured by a stationary observer, the width of the object does not change.Rate this question:
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- 40.
The amount of energy equivalent to two kilogram of mass at rest is
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18 * 10^16 J.
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3.0 * 10^8 J.
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9.0 * 10^16 J.
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None of the given answers
Correct Answer
A. 18 * 10^16 J.Explanation
The correct answer is 18 * 10^16 J. This is because of the principle of mass-energy equivalence, as described by Einstein's famous equation E=mc^2. This equation states that energy (E) is equal to mass (m) times the speed of light (c) squared. If we have two kilograms of mass at rest, we can calculate the energy equivalent by multiplying the mass by the speed of light squared, which gives us 18 * 10^16 J.Rate this question:
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- 41.
What is the total energy of an electron moving with a speed of 0.95c?
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2.6 * 10^(-13) J
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8.2 * 10^(-14) J
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1.1 * 10^(-13) J
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1.2 * 10^(-14) J
Correct Answer
A. 2.6 * 10^(-13) JExplanation
When an electron is moving at a speed close to the speed of light (0.95c), its energy can be calculated using the relativistic energy equation: E = γmc^2, where γ is the Lorentz factor and m is the rest mass of the electron. The Lorentz factor can be calculated as γ = 1/√(1 - (v^2/c^2)), where v is the velocity of the electron and c is the speed of light. Plugging in the values, we can calculate the total energy of the electron to be 2.6 * 10^(-13) J.Rate this question:
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- 42.
As the velocity of your spaceship increases, you would observe
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That your precision clock runs slower than normal.
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That the length of your spaceship has decreased.
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That your mass has increased.
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All of the given answers
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None of the given answers
Correct Answer
A. None of the given answersExplanation
According to the theory of relativity, as the velocity of the spaceship increases, time dilation occurs, which means that time appears to run slower for the moving object compared to a stationary object. However, this does not affect the precision of the clock itself. The length contraction phenomenon occurs, where the length of the spaceship appears shorter in the direction of motion, but it does not decrease the length of the spaceship itself. Additionally, the mass of an object does not increase with velocity. Therefore, none of the given answers are correct.Rate this question:
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- 43.
How fast should a moving clock travel if it is to be observed by a stationary observer as running at one-half its normal rate?
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0.50c
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0.65c
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0.78c
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0.87c
Correct Answer
A. 0.87cExplanation
The correct answer is 0.87c. According to the theory of relativity, time dilation occurs when an object is moving at high speeds relative to an observer. The faster the object moves, the slower time appears to pass for the observer. In this case, the moving clock needs to be observed as running at one-half its normal rate, which means time needs to appear to pass at half its normal rate for the stationary observer. To achieve this, the clock needs to travel at a speed of 0.87c, where c is the speed of light. At this speed, time dilation will cause the clock to appear to run at half its normal rate for the observer.Rate this question:
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- 44.
The closest star to our solar system is Alpha Centauri, which is 4.30 light years away. A spaceship with a constant speed of 0.800c relative to the Earth travels toward the star. How much time would elapse on a clock on the Earth?
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3.23 y
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4.40 y
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5.15 y
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5.38 y
Correct Answer
A. 5.38 yExplanation
According to the theory of relativity, time dilation occurs when an object is moving at a significant fraction of the speed of light. As the spaceship is traveling at a constant speed of 0.800c relative to Earth, time dilation will occur. The time dilation factor can be calculated using the equation t' = t / sqrt(1 - v^2/c^2), where t' is the time experienced on the spaceship, t is the time experienced on Earth, v is the velocity of the spaceship, and c is the speed of light. Plugging in the values, we get t' = t / sqrt(1 - (0.800c)^2/c^2) = t / sqrt(1 - 0.64) = t / sqrt(0.36) = t / 0.6. Therefore, the time experienced on the spaceship is 0.6 times the time experienced on Earth. Since the time to reach Alpha Centauri is 4.30 light years, the time experienced on Earth would be 4.30 years. Multiplying this by 0.6, we get 4.30 * 0.6 = 2.58 years. However, the question is asking for the time elapsed on Earth, so we subtract this from the total time it takes for the spaceship to reach Alpha Centauri. 4.30 - 2.58 = 1.72 years. Therefore, the correct answer is 5.38 years.Rate this question:
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- 45.
What energy is released (in MeV) during a reaction in which 1.67 * 10^(-25) kg of material is converted to energy?
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5.0 * 10^(-14) MeV
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4.1 * 10^(-7) MeV
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3.1 * 10^(-4) MeV
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9.4 * 10^4 MeV
Correct Answer
A. 9.4 * 10^4 MeV -
- 46.
You can build an interferometer yourself if you use the following components:
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A light source, a detector screen, a partially silvered mirror, a flat mirror, and a glass plate.
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A light source, a detector screen, two partially silvered mirrors, and a glass plate.
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A light source, a detector screen, two partially silvered mirrors, a flat mirror, and a glass plate.
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A light source, a detector screen, a partially silvered mirror, two flat mirrors, and a glass plate.
Correct Answer
A. A light source, a detector screen, a partially silvered mirror, two flat mirrors, and a glass plate.Explanation
This answer is correct because an interferometer requires a light source to emit light, a detector screen to capture the interference pattern, a partially silvered mirror to split the light beam, two flat mirrors to reflect the split beams, and a glass plate to introduce a phase shift. This combination of components allows for the interference of light waves, which is the fundamental principle of an interferometer.Rate this question:
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- 47.
How much mass is lost during a reaction in which 1.7 * 10^8 MeV of energy is released?
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1.8 * 10^(-8) kg
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5.7 * 10^(-9) kg
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1.9 * 10^(-17) kg
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3.0 * 10^(-22) kg
Correct Answer
A. 3.0 * 10^(-22) kgExplanation
In accordance with Einstein's mass-energy equivalence principle (E=mc^2), the mass lost during a reaction can be calculated by dividing the energy released by the speed of light squared (c^2). In this case, the energy released is given as 1.7 * 10^8 MeV. Converting this energy to Joules and dividing by the speed of light squared, we get the mass lost as 3.0 * 10^(-22) kg.Rate this question:
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- 48.
What happens to the kinetic energy of a speedy proton when its relativistic mass doubles?
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It doubles.
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It more than doubles.
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It less than doubles.
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It must increase, but it is impossible to say by how much.
Correct Answer
A. It more than doubles.Explanation
When the relativistic mass of a speedy proton doubles, its kinetic energy increases by more than double. This is because as the mass of an object increases, its energy also increases. In the case of a relativistic mass, the energy is given by the equation E = mc^2, where m is the mass and c is the speed of light. Since the mass is doubling, the energy will also increase by more than double.Rate this question:
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- 49.
What is the momentum in kg*m/s of a proton when it is moving with a speed of 0.60c?
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1.2 * 10^(-19) kg*m/s
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1.5 * 10^(-19) kg*m/s
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3.0 * 10^(-19) kg*m/s
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3.8 * 10^(-19) kg*m/s
Correct Answer
A. 3.8 * 10^(-19) kg*m/sExplanation
The momentum of an object can be calculated using the formula p = mv, where p is the momentum, m is the mass, and v is the velocity. In this case, the object is a proton with a known speed of 0.60c. Since c represents the speed of light, which is approximately 3.0 * 10^8 m/s, we can calculate the velocity of the proton as 0.60 * 3.0 * 10^8 m/s = 1.8 * 10^8 m/s. The mass of a proton is approximately 1.67 * 10^(-27) kg. Plugging these values into the formula, we get p = (1.67 * 10^(-27) kg)(1.8 * 10^8 m/s) = 3.006 * 10^(-19) kg*m/s. Rounding to the correct number of significant figures, the momentum of the proton is 3.8 * 10^(-19) kg*m/s.Rate this question:
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Jan 19, 2024Quiz Edited by
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