/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 2 A rocket is moving to the right ... [FREE SOLUTION] | 91Ó°ÊÓ

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A rocket is moving to the right at half the speed of light relative to the earth. A lightbulb in the center of a room inside the rocket suddenly turns on. Call the light hitting the front end of the room event \(A\) and the light hitting the back of the room event \(B\). (See Figure 27.23.) Which event occurs first, \(A\) or \(B\), or are they simultaneous, as viewed by (a) an astronaut riding in the rocket and (b) a person at rest on earth?

Short Answer

Expert verified
(a) Simultaneous for the astronaut; (b) A occurs before B for the Earth observer.

Step by step solution

01

Understanding the Situation

We have a rocket moving at half the speed of light relative to Earth. Inside the rocket, a lightbulb is turned on at the center of a room. We need to determine when the light hits the front and back ends of the room, which are events A and B.
02

Analyzing from Astronaut's Perspective

For the astronaut inside the rocket, both ends of the room are equidistant from the lightbulb. Thus, they will perceive the light to reach both ends simultaneously. Therefore, from the astronaut's frame of reference, events A and B are simultaneous.
03

Analyzing from Earth Observer's Perspective

Since the rocket is moving to the right at half the speed of light, the front of the room is moving towards the point where the light originated, and the back moves away from it. The light reaches the front of the room first because it is moving towards the light source, resulting in event A occurring before event B in the Earth observer's frame of reference.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Rocket Physics
Rocket physics involves understanding how a rocket moves and behaves in different frames of reference, especially when it involves high speeds, such as a fraction of the speed of light. In this scenario, the rocket is moving at half the speed of light relative to the Earth. This is a significant speed which introduces effects predicted by Einstein's theory of special relativity. The room inside the rocket is crucial to our understanding of simultaneity because the events that occur inside it (the light reaching the front and back) happen while the rocket is in motion. The movement at such high speeds affects how events are perceived by observers inside and outside the rocket. Understanding the behavior of the rocket at these speeds helps illustrate key principles of special relativity, such as how time and space are interlinked. It also shows how speeds approaching that of light can lead to non-intuitive results, making these studies not only fascinating but essential for modern physics.
Simultaneity
Simultaneity is a concept in special relativity that challenges our everyday understanding of time. It describes how two events are perceived as occurring at the same time in one frame of reference but not necessarily in another. In the scenario with the rocket, for the astronaut traveling with the rocket, the light from the bulb reaches both the front and the back of the room simultaneously because both points are equidistant from the bulb. This is the astronaut's frame of reference. However, for the observer on Earth, who sees the rocket moving to the right, simultaneity is lost. The front of the room moves towards the light, making event A (light hitting the front) happen first, followed by event B (light hitting the back). This brings out the essence of special relativity: simultaneity is relative. What is simultaneous in one frame may not be in another, depending on their relative motion. This principle was one of Einstein's major revelations that has profound implications for our understanding of time and space.
Relative Motion
Relative motion is a key aspect of understanding phenomena in special relativity. It refers to how the observed motion of an object depends on the observer's frame of reference. In the context of this exercise, the relative motion between the rocket and the Earth is crucial. For the astronaut inside the rocket, the rocket itself is at rest, and hence, both ends of the room are equidistant and stationary relative to them. Therefore, they see light reaching both ends simultaneously. For an observer on Earth, however, the rocket is moving. As the room inside the rocket travels, the front of the room sweeps into the light first. This discrepancy arises because the observer's frame of reference on Earth is different. This exercise serves to illustrate how motion is relative and dependent on who's observing it. It shows that there are no absolute frames of reference; instead, all motion is observed in relation to different observers, a fundamental part of the theory of special relativity.

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Most popular questions from this chapter

How fast must a rocket travel relative to the earth so that time in the rocket "slows down" to half its rate as measured by earth-based observers? Do present-day jet planes approach such speeds?

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