Questions tagged [inertial-frames]

A specific reference frame that describes its coordinates in a manner that does not depend on time and is isotropic.

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Why physics should be the same in all inertial frame?

One of the postulates of special relativity is that physics should be the same in all inertial frame. Suppose we have two observers $A$ and $B$ suppose that $A$ is accelerated. Now suppose that we ...
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Why is force invariant under a Galilean transformation? [duplicate]

I've had a look around online, but I haven't been able to find something which answers this in a way I understand. Essentially, I'm trying to figure out why force is invariant under a Galilean ...
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Inertial Forces while analysing forces on a Piston in a Slider - Crank Mechanism? [on hold]

I get that we are analysing the Piston in a Non - Inertial Frame of Reference, but the point of my question is that according to D'Alemberts Principle, whenever an Inertial Force comes in the line of ...
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Can Newton's laws be reformulated with reference to “relative” frames

I was reading: https://arxiv.org/abs/1205.2326 page 2 which gives thorough discussion of the three laws. In particular there is a refutation of the (paraphrased) 2nd law implies the first because ...
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Einstein's train, considering the thunder

From Einstein's "easy" explanation https://www.bartleby.com/173/9.html (Yes, I have reviewed 8 other answers to similar questions. Please bear with me.) M is on the platform, T (aka M') is on the ...
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Which frame to consider for time dilation? [duplicate]

Clearly for constant motion we cannot define absolute rest or motion. So ,when dealing with time dilation problems for example twin paradox , how do we define which frame is in motion? If we ...
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Basic Special Relativity Question [closed]

I am trying to understand the implications of c being relative to the frame of reference. Is the following analysis correct? N is on a slow train moving 3 m/s and M on the platform next to N both ...
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Sum of gravitational force $W$ and contact force $N$ on a book at rest on table is not 0

There is a book on the table fixed rigidly to the earth. The book is at rest with respect to the earth. The acceleration of this book with respect to the earth is 0. The forces on this book are a) ...
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Using Lorentz transformations with variable velocity

A particle is moving in a system of reference $S$. In its proper system of reference, say $S'$, the particle is still and it is described by the event $(c\tau,0,0,0)$. In the inertial frame $S$, the ...
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Are laws of Physics same in frames having zero relative acceleration?

If two frames have the same acceleration, then they'll be moving with a uniform speed with respect to each other. Are laws of Physics the same in these two frames?
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Grasping (Inertial) Frames of Reference [duplicate]

I am new to studying Special Relativity and have some trouble truly understanding what the phrase (Frame of Reference) tries to imply. So I understand that an inertial frame of reference, for example,...
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Is kinetic energy relative? [duplicate]

Assume there is a rocket with 10 kg of fuel in a large empty space without any external forces such as gravity. Rocket burns 1 kg of fuel and gets a $v_1$ velocity gain. Now it is moving in $v_1$ ...
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How can we tell if the Earth is spinning without any external references? [duplicate]

The rotation of the Earth about its axis makes it bulge at the equator and contract at the poles due to the centrifugal forces. How do we know, without any external references, that the Earth is ...
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Lorentz Transformation Perpendicular Photons

I'm trying to derive the Lorentz Transformation on my own but I'm stuck. This is probably something stupid, but I cannot figure out why I am not getting this right. enter image description here Here'...
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The Proof of $\cos\phi=\gamma$ Equation in Special Relativity [closed]

In the Introductory Special Relativity book, by W. G. V. Rosser, page 182, Section 7.3, the author is defining the 4-vector methods using complex numbers. In his derivation, he writes the following ...
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With respect to what does a Gyroscope maintain its orientation?

Assume ideal conditions, no friction, no energy loss in any form. Just an ideal gyro, in ideal conditions, spun into rotation and left alone. And placed somewhere on earth. From what I've read so ...
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Which Frame of Reference is Correct?

I am reading a lot about the theory of special relativity, but I have a very basic question about this theory I still don't understand. Consider a particle in two inertial reference frames $\Sigma$ ...
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A best definition of proper acceleration

In this link of Wikipedia https://en.wikipedia.org/wiki/Hyperbolic_motion_(relativity) there is a definition of proper acceleration: The proper acceleration to a particle is defined as the ...
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Motion between two particles in a relative manner

Suppose a particle A is travelling in east direction with velocity of x m/s and another particle B is travelling with velocity y m/s in the west direction. Why does the the particle B appears to move ...
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1answer
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Force on a moving charge in 2 frames

The following simple problem seems to lead to a contradiction when analyzed in different frames. Consider an infinitely long stationary wire with positive line charge density $\lambda_0$ and ...
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Relative speed when getting close to the speed of light

I was thinking about the relative speed of an observation reference frame and an object which has been accelerated to a speed close to the speed of light. I'm by no mean an expert and the last physics ...
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1answer
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Relative motion between two particles

I already know the relation of relative velocity as : Vab=Va-Vb So is there any derivation for this relation or is just how it is defined? Relating to this i am finding some hard time to imagine why ...
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Components of speed of light

I'd like to start off by saying this may be totally wrong; thus I would like some help clarifying this. Suppose you are in a vacuum, and a beam of light is travelling at, say, a N$45°$E bearing. The ...
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Free-float frames and inertial frames [duplicate]

In the book Spacetime Physics by Taylor and Wheeler, a free-float reference frame is defined as a reference frame where every free particle initially at rest with respect to that frame remains at ...
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How can I show that the speed of light in vacuum is the same in all reference frames?

I have regularly heard that the Michelson-Morley experiment demonstrates that the speed of light is constant in all reference frames. By doing some research I have found that it actually demonstrated ...
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Different forces from different inertial frames?

I've been having trouble understanding this equation here derived in the picture given below. If I change reference frames to one which is moving at a velocity u with respect to the first frame, then ...
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Interaction between various forces, by which one is to calculate an angle? [closed]

I am new to Newtonian mechanics, and was wondering about the following question. I basically have the ingredients for the answer, but I cannot seem to find the way to put this together into one ...
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Has this group something to do with the cone of light?

Consider the group $V=(-1,1)$ with addition $+_{rel}:V\times V\to V$ defined as: $$v+_{rel}w=\frac{v+w}{1+vw}$$ This group is analogous to the relativistic velocities where the speed of light equals ...
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To Be Forever Young [duplicate]

It is clear from the Lorentz Parameters, applied to Einstein's Equations, that as velocity, v approaches speed-of-light, c, the denominator (1 - [v/c]) tends to zero; when v=c, time, t=0: time stops?! ...
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Why is the Earth not an inertial frame of reference?

From many sources I have found the explanation that the Earth is not an inertial frame of reference because it rotates around its axis. However, nobody mentions the rotation about the Sun. What I ...
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Still confuse about tensor

In special relativity, a four-vector $\mathbf{x}$ in an inertial frame is related to $\mathbf{\overline{x}}$ through a Lorentz transformation $\mathbf{\Lambda}$: \begin{align} \overline{\mathbf{x}}...
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Is Landau&Lifshitz's argument for the classical Lagrangian's symmetries too strict?

I realize that this paragraph has raised more questions on stackexchange, but I wanted to ask this question nevertheless since I want to discuss it in terms of a counter-example. I’ve already ...
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A concise definition of a frame of reference in Newtonian mechanics?

I've read Wikipedia's entry on frame of reference and also followed all of the references cited in the text (Salençon, Brillouin, Norton, etc) but I'm struggling to find any concise definition in all ...
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Sound wave and Principle of relativity

Principle of Relativity: "An experimenter doing an experiment in an inertial frame of reference can never measure the velocity of its own frame of reference. OR a law of physics is never expressed ...
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Validity of Newton's second law in a non-inertial reference frame

Suppose two observers are mutually interact through gravitational force (assuming they are alone at space). If the reference frame is fixed in one of the observers could the observer in the reference ...
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Motivation for the abandonment of inertial frames in general relativity [closed]

Inertial frames are at the core of special relativity. The laws of physics are supposed to be the same among them and free particles follow rectilinear paths in spacetime or simply stay at rest. Just ...
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Why the velocity $v$ is taken as value and not as definition in special relativity equations?

Why the velocity $v$ is taken as a value and the definition of velocity not applied on a relativistic equations? The equations of time dilation and length contractions as we know are $$L = {L_0}{\...
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Colliding elastically in lab and CM frame

Two spherical bodies of mass $m_1$ and $m_2$ are placed in gravity free space as shown. Initially, the body with mass $m_2$ is at rest and the body with mass $m_1$ approaches the other body with a ...
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Example of anisotropy frame of reference

I have studied that an inertial frame of reference is the one that is homogeneous, isotropic and time-independent. For instance, a reference frame on a rotating wheel is not an inertial frame of ...
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Exact difference between '''Fermi normal coordinates''' and ''Riemann normal coordinates'''? [duplicate]

I want to know the exact difference between '''Fermi normal coordinates''' and ''Riemann normal coordinates'''? Here is a same question, but it's hard for me to understand. Difference between Fermi ...
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Why can't we take space as universal frame of reference?

Suppose we have a ball filled half with water in space with nothing else around (nothing else in the whole space except the ball) and suddenly it accelerates for time t. obviously, there would be ...
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What do you mean by Newtonian space? [closed]

What do you mean by Newtonian space? When you see this question, most of you might be thinking that I am trying to crack a joke or something..but no. This was a genuine doubt which one of my friends ...
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Is it possible writing conservation of relativistic energy in this naive way?

Conservation of charge or rest mass can be written in this way and it is Lorentz invariant $$ \nabla \cdot (\rho \mathbf{u}) + \frac{\partial \rho}{\partial t} = 0 $$ So we could be tempted to naively ...
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The interference paradox

This is a thought experiment I created myself. Imagine two radio sources fixed at the ends of a rocket and they produce signal of same frequency such that they arrive at the center simultaneously and ...
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On local inertial frame and acceleration in general relativity

[Q1] In the general relativity, a local inertial frame is mentioned. The local inertial frame is a notion, which is related to (or represents) the equivalent principle. Here, I understand that, in ...
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Difficulty in understanding why a car slips towards outside as seen from inertial frame

While turning on a road, why does a car slip towards outside, if we are observing the car from inertial frame of reference, i.e center?
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In Special Relativity, is it allowed to ask 'How much time has elapsed in a second inertial frame at a particular moment in the first inertial frame'?

Or is it a meaningless question? For example, A and his friend B are the same age initially. B travels relative to A at a very high speed. A keeps observing B from his frame. At one moment, A ...
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To prove: the integration measure is Lorentz invariant (Schwartz's problem 2.6b)

I am stuck on Schwartz's ("Quantum Field Theory and the Standard Model") problem 2.6b, and would be grateful for clarification. (I'm aware that this question has been asked and answered elsewhere (...
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What's incorrect about this reasoning regarding special relativity?

Say two spaceships start at the same point and from the vantage point of your inertial reference frame $S$, Spaceship A travels at $.75c$ and Spaceship B travels at $.25c$, travelling in the same ...
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Special Relativity - Reference Frames $S$ and $S'$

Consider the standard arrangement in special relativity. Let S' move in the +ve x-axis with a velocity V with respect to S Question: S then moves with a velocity -V with respect to S'. Is this an ...