All Questions
Tagged with galilean-relativity relative-motion
25 questions
2
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If an observer was trapped in a closed box with no way to interact with the external surroundings how will he know if he is moving or at rest [duplicate]
I am a high-school student. Recently we learned the concepts of relative motion and velocity. The idea that anything in motion can subsequently be at rest depending on the frame of reference ...
- 21
1
vote
1
answer
77
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Principle of Relativity and the invariance of Newton's law in IRFs
Newton's law are form invariant under the coordinate substitutions:
$$
\tilde{x^{i}}=x^{i}+a^{i}
$$
This means that Newtons' equation of motion,
$$
F^{i}=m \frac{d^{2} x^{i}}{d t^{2}}
$$
(where $i=1,2,...
- 11
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2
answers
79
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In galilean relativity, is an observer assumed to be at rest only to simplify calculations, or is there a physical reason for this assumption?
I am a beginner in Physics and my teacher taught us "Relative Motion" yesterday. He said that the "Observer is assumed at rest." Is the observer assumed to be at rest only to ...
0
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2
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91
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Question about relative motion from "A Brief History of Time" [closed]
I read this example in Stephen Hawking's A Brief History of Time:
If one sets aside for a moment the rotation of the Earth and its orbit round the Sun, one could say that the Earth was at rest and ...
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2
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5
answers
132
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If motion relative to a frame of reference is purely relative, how do we account for the work done to move relative to the frame of reference?
I get the idea that everything is in motion, and there's no absolute reference frame for everything.
But when we consider local events, like a train passing through a town, I have trouble accepting ...
0
votes
2
answers
319
views
Why is relative motion at constant velocity the same as being at rest?
If I am a passenger who plays catching-the-ball game inside a vehicle that moves with a constant velocity in a straight road, why can I catch the ball repeatedly that as if the vehicle is at rest? How ...
user282164
0
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1
answer
76
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Is there a Group that covers (classical) relative velocities?
I'm not very well versed in Abstract algebra and group theory, so this question might not make sense to begin with, but I got an idea when reading up on how to rigorously calculate relative velocities....
- 163
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3
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What does it mean that two frames are " in a state of constant, rectilinear motion with respect to one another"?
This expression ( applied to reference frames) " being in a state of constant, rectilinear motion with respect to one another "is frequently used as self explanatory . Though I might appear as stupid, ...
user229097
1
vote
3
answers
256
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Defining what it means for a reference frame to move with a velocity $\mathbf{u}$ with respect to another
In describing a Galilean transformation, for example, one might say that if a reference frame $S'$ is moving at a velocity $\mathbf{u}$ with respect to $S$, then an object traveling at a velocity $\...
user113773
1
vote
1
answer
201
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How does Kinetic Energy transform from one frame of reference to another?
Let's say I observe a charge q floating in the middle of space. I set up another charge Q a distance d away from charge q was causes a force F to act on charge q. As charge q moves away from charge ...
- 163
3
votes
1
answer
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Can we really not tell if we are moving?
It has been a while since I've thought about physics, however, I remember something about how if you are on a train with no windows that is going perfectly straight and is perfectly smooth, there is ...
- 133
2
votes
0
answers
348
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Observer Watching a Ball Thrown Up on A Train [closed]
Let's suppose I'm on a train, moving with constant speed V1. At a time T1 I throw a ball up in the air, the ball do not accelerate but has constant velocity V2, and, in this hypotetical scenario, no ...
6
votes
1
answer
838
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Shouldn't the escape velocity of earth (with respect to earth) be less than $\sqrt{\frac{2GM}{R}}=11.2\,\mathrm{km/s}$
We know that the escape velocity of earth is,
$$\sqrt{\frac{2GM}{R}}=11.2\,\mathrm{km/s}$$
Where $G=6.67×10^-11$
$M=\text{mass of earth}$
$R=\text{radius of earth}$
So if throw a object ...
- 732
1
vote
1
answer
69
views
What relative motion tells me about a motorbike shooting out from a bus?
I imagined this situation:
Suppose I'm on a motorbike inside a long bus that has a constant velocity v on a street.
I start accelerating (in the direction opposite to the motion of the bus) till ...
0
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2
answers
2k
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The Meaning of Newton's Second Law of Motion Being Invariant Under Certain Transformations
What do we mean when we say that Newton's Second Law of Motion is invariant under Galilean transformations?
Does it mean that the value of a force measured in one reference frame is the same when ...
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5
answers
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Is it possible to stay up while riding a bike on a moving sidewalk without actually moving?
If I ride a bicycle on a moving sidewalk so that I am not in effect moving at all relative to the ground, will I fall over?
- 329
3
votes
1
answer
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Calculating relative velocity in three dimensional space
Given two points $\mathcal{A}$ and $\mathcal{B}$ in $\mathbb{R^3}$ whose position and velocity vectors are, respectively:
$$\mathbf{r_A}=\begin{pmatrix}r_{A_{x}}\\r_{A_{y}}\\r_{A_{z}}\end{pmatrix}$$
$$...
- 133
-1
votes
1
answer
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While jumping in a high speed train why we fall on same place? [duplicate]
while we jump inside a high speed train why do we fall on the exact place?
as train is in high speed and we are jumping so we should fall backside. but this doesn't happen why?
1
vote
1
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Can the use of a magnetic compass be inconsistent with Galileo's Relativity Hypothesis?
I just read Galileo's Relativity Hypothesis from this website:
http://physics.ucr.edu/~wudka/Physics7/Notes_www/node47.html
It states that -
"any two observers moving at constant speed and direction ...
- 203
0
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2
answers
129
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Does it take less time to drop a ball than fire one horizontally (with $90^{\circ}$) [closed]
So I was arguing about this with my friend. If we take two balls and drop one from a certain height H and then fire another one with horizontally with some initial speed from the same height H, which ...
- 505
3
votes
4
answers
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Stone dropped from a moving train
This may look like a stupid question, but it is really getting to me. Imagine a train moving with an acceleration $a$, and a person drops a stone from the window. To an observer on the ground, the ...
- 2,778
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3
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Is it possible to tell whether the space ship is moving or not?
Consider a space ship which is not under any force. Being inside the space ship, I will make a robotic fly from the platform to crawl inside using my remote. For simplicity assume that space ship will ...
- 5,839
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answers
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Inertial Frames of Reference - Inertial vs. Accelerated Frames
According to Robert Resnick's book "Introduction to Special Relativity", a line states the following as the definition of an inertial frame of reference: "We define an inertial system as a frame of ...
- 383
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1
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722
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Galilean relativity in projectile motion
Consider a reference frame $S^'$ moving in the initial direction of motion of a projectile launched at time, $t=0$. In the frame $S$ the projectile motion is:
$$x=u(cos\theta)t$$
$$y=u(sin\theta)t-\...
- 567
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votes
2
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Why absoluteness of time implies galilean transformations?
In Landau course, vol.1 Mechanics, one finds the statement:
...the absoluteness of time necessarily implies that the ordinary law of composition of velocities is applicable to all phenomena.
I ...
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