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Mobile App Chapter 18: Problem 10
Relative motion between two objects is apparent a. even at everyday speeds, such as \(10 \mathrm{km} / \mathrm{h}\). b. only at very large speeds, such as \(0.8 \mathrm{c}\) c. only near very large masses. d. only when both objects are in the same reference frame.
Short Answer
Expert verified
a. even at everyday speeds, such as 10 km/h.
Step by step solution
01
Understanding Relative Motion
Relative motion refers to the calculation of the movement of an object with respect to another object. This concept is essential in both everyday life and significant physics applications, allowing us to measure how fast or slow an object is moving compared to another.
02
Review the Options
Examine each answer choice to determine when relative motion becomes apparent: a. at everyday speeds, such as 10 km/h. b. at very large speeds, such as 0.8c. c. near very large masses. d. when both objects are in the same reference frame.
03
Analyzing Option A
Option a states that relative motion is apparent at everyday speeds such as 10 km/h. Relative motion is indeed noticeable at such speeds, as we can see the difference in speed when, for example, walking past a stationary car.
04
Analyzing Option B
Option b mentions very large speeds such as 0.8c (where c is the speed of light). Relativistic effects become noticeable at such high speeds, but relative motion is not limited to these extreme cases alone. Therefore, this option is too specific.
05
Analyzing Option C
Option c states that relative motion is apparent only near very large masses. This option is referring to gravitational effects, which is a different concept from general relative motion.
06
Analyzing Option D
Option d states that relative motion is only apparent when both objects are in the same reference frame. This is incorrect because relative motion can be observed between objects in different reference frames as well.
07
Selecting the Correct Answer
Based on the analysis, the correct answer is option a. Relative motion is apparent even at everyday speeds, such as 10 km/h.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
everyday speeds
Relative motion is a concept that we encounter daily. Even at low speeds, like when walking past a parked car, we can perceive the difference in movement. Understanding motion at everyday speeds, such as 10 km/h, is crucial because it allows us to relate to and interpret our surroundings.
For example, if you are on a moving bus and observe a tree outside, you perceive the tree as moving backward while you move forward. This is relative motion in action. Hence, motion doesn't need to be extremely fast or near massive objects to be noticeable. It's something we experience continuously in our day-to-day lives.
For example, if you are on a moving bus and observe a tree outside, you perceive the tree as moving backward while you move forward. This is relative motion in action. Hence, motion doesn't need to be extremely fast or near massive objects to be noticeable. It's something we experience continuously in our day-to-day lives.
reference frame
A reference frame is essentially a perspective from which you observe and measure phenomena. It's a coordinate system or a point of view of where measurements like position, velocity, and time are taken.
Imagine standing on a platform and watching a train go by. Your reference frame is the platform, and from this frame, the train is in motion. Now, if you were inside the train and watching another person walking, your reference frame would be the train itself. The person moving inside the train may appear to move differently or not at all compared to an observer on the platform.
Imagine standing on a platform and watching a train go by. Your reference frame is the platform, and from this frame, the train is in motion. Now, if you were inside the train and watching another person walking, your reference frame would be the train itself. The person moving inside the train may appear to move differently or not at all compared to an observer on the platform.
- Important Point: Relative motion can be observed when objects are in different reference frames.
- Observation changes based on whether the reference frame is stationary or moving.
relativistic effects
Relativistic effects become significant when dealing with extremely high speeds, close to the speed of light (denoted as c). When objects move at such large percentages of the speed of light, classical physics like Newtonian mechanics no longer applies, and we begin to use Einstein's theory of relativity.
For example:
For example:
- Time Dilation: Moving clocks run slower compared to stationary ones when traveling at high speeds.
- Length Contraction: Objects shorten in the direction of motion as their speed approaches the speed of light.
gravitational effects
Gravitational effects come into play when large masses are involved. According to Einstein's General Theory of Relativity, massive objects such as planets, stars, and black holes affect the fabric of space-time, bending it and causing what we perceive as gravity.
For instance, Earth's gravity affects everything on it, dragging objects to its surface. However, near extremely massive bodies like black holes, gravitational effects become far more intense and noticeable.
Gravitational effects explain:
For instance, Earth's gravity affects everything on it, dragging objects to its surface. However, near extremely massive bodies like black holes, gravitational effects become far more intense and noticeable.
Gravitational effects explain:
- Why the Moon orbits the Earth.
- How light bends around massive objects, an effect known as gravitational lensing.
- Why time moves slower closer to strong gravitational fields, known as gravitational time dilation.
