Tagged Questions

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

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0answers
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Does a mass gain inertia against movement in all directions as it approaches the speed of light?

If a mass moves along the x axis at near the speed of light, does it take as much energy to additionally accelerate the mass along the y axis as it does to accelerate it along the x axis by the same ...
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1answer
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Fictitious forces and $\omega$

I have been studying fictitious forces, such as the centrifugal force and Coriolis force. The equation for the centrifugal force is given by: $$F_{centrifugal}=-m\omega\times(\omega\times r)$$ My ...
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2answers
136 views

Handedness of Reference Frames?

I am developing a new derivation of the Lorentz transformation which I think and hope is more attractive to students than those I have seen in currently available texts. I am carefully defining and ...
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1answer
102 views

Don't Inertial forces obey Newton's third law? [duplicate]

I read in a book (Fundamentals of Mechanics by IE Irodov) that inertial forces do not obey newton's third law. I am unable to imagine and get this in my mind. It states: "Inertial forces are not ...
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2answers
81 views

Newtonian physics [duplicate]

According to the book I am referring while working with non inertial frame of reference we have to apply a pseudo force equal to mass x acceleration in the opposite direction of the acceleration of ...
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5answers
1k views

What problems with Electromagnetism led Einstein to the Special Theory of Relativity?

I have often heard it said that several problems in the theory of electromagnetism as described by Maxwell's equations led Einstein to his theory of Special Relativity. What exactly were these ...
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2answers
94 views

Inertial frames

I'm just starting my study of relativity, and I have a rough understanding of the connection between inertial frames, newton's laws, and galilean transformations, but I'd probably benefit more if ...
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3answers
60 views

How to differentiate between rotating frame and linearly accelerating frame?

Two friends, $A$ and $B$ are part of an experiment. $A$ is placed in a closed box and made to accelerate in free space at an acceleration $g$. $B$ is also placed in a closed box, but is made to rotate ...
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1answer
51 views

Physical laws in all inertial frames

Do there exist physical laws which do not take the same form in all inertial frames?
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2answers
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Invariance of Temperature in Classical Physics

How can we explain that Temperature is a classically frame-independent quantity to high school kids?
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2answers
131 views

Why is Newton's first law necessary?

Newton's second law says $F=ma$. Now if we put $F=0$ we get $a=0$ which is Newton's first law. So why do we need Newton's first law ? Before asking I did some searching and I got this: Newtons first ...
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1answer
93 views

Gravity vs inertia

As stated according to Newton laws of gravity, every object with mass attracts all other object with a force which produces acceleration. Basically there are several forces in the universe which ...
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2answers
202 views

Understanding the “$\pi$” of a rotating disk

Let us say you are in an inertial reference frame with a circular planar disk. If you take your meter measuring rods (or perhaps tape measure) you can find the diameter and circumference of the disk. ...
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1answer
40 views

Inertial navigation system: am I doing it wrong?

I'm trying to develop an inertial navigation system. I can access data from an accelerometer sensor (acceleration on three axes) and gyroscope sensor (angular velocity on three axes). First of all, ...
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1answer
47 views

Inertial frame: Sun earth and moon

From the perspective of sun, is the moon orbiting the earth considered a single inertial frame or are moon and earth separate inertial frames? Or am I missing something completely fundamental?
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3answers
109 views

Rotating reference frames

I'm trying to understand the equations that govern velocity in a rotating reference frame... \begin{equation} v_i = (\frac{dr}{dt})_r + \Omega \times r . \end{equation} I'd like to build a simple ...
2
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1answer
55 views

Relative Motion and orbiting planets [duplicate]

if all motion is relative to the frame of reference determined by an observer, why would the view that planet earth revolves around the Sun more correct than the view that the Sun revolved around ...
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2answers
100 views

Inertial Frames in Special Relativity

According to the postulates of special relativity, all inertial frames are equal in all respects. Then how does it follow from this, that the space is isotropic and homogenous for an inertial frame ...
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3answers
65 views

Why doesn't any object that doesn't have direct contact in a fast moving vehicle feel G-force or slam behind or ahead when braked or accelerated?

Why doesn't any object that doesn't have direct contact in a fast moving vehicle feel G-force or slam behind or ahead when braked or accelerated? For example when we are in a car (even with all ...
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3answers
484 views

Do we need inertial frames in Lagrangian mechanics?

Do Euler-Lagrange equations hold only for inertial systems? If yes, where is the point in the variational derivation from Hamilton's principle where we made that restriction? My question arose ...
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1answer
72 views

Heliocentric Worldview [duplicate]

Isn't the whole historic Discussion of Heliocentric vs. Geocentric Worldview just about a Calculation-Technique. I mean I could also choose my coordinate-center to be in the middle of Earth and setup ...
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1answer
106 views

Does action really have to be Lorentz-invariant in SR?

From Landau & Lifshitz The Classical Theory Of Fields it is said: To determine the action integral for a free material particle (a particle not under the influence of any external force), we ...
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2answers
124 views

What is use of inertial frames

In class of Newton's laws of motion, it was explained that Newton's second law is valid only in inertial frames. Teacher give us a example by considering a lift which is going downwards with ...
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0answers
82 views

Light cones and reference frames

I'd like to know what does it mean exactly to find a reference frame in which two events occur at the same time or in the same space coordinates. As I picture it if we have two events A and B in a (x, ...
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3answers
333 views

Does the Relativity Principle of Special Relativity imply homogeneity and isotropy of all the reference frames?

In Rindler's book: Relativity, Special, General and Cosmological, is stated on page 40 that the Relativity Principle (RP), when applied to just one Inertial Frame (IF), guarantees the homogeneity and ...
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2answers
113 views

Is the assumption that the two reference frames be inertial required in the derivation of transformation equations?

In the derivation of Galilean transformations the only assumption is that the two frames are moving with some uniform relative velocity $u$. Suppose with respect to some inertial frame $O$ the two ...
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3answers
158 views

Do bullet/gun physics change if the gun is traveling very fast?

If I'm running at say $400\: \mathrm{m/s}$ and a bullet travels at $400\: \mathrm{m/s}$ and I fire the gun, will I see the bullet leave the barrel? I either see it stay in the barrel floating ...
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1answer
170 views

What is the significance of Einsteins postulate on speed of light?

Einstein postulated that the speed of light in free space is the same for all observers, regardless of their motion relative to the light source, where we may think of an observer as an imaginary ...
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1answer
49 views

Relative speed of objects

This question has been bugging me for a while now. I am not sure this is the correct forum to ask, please close if it is not the right forum. Lets say a bus is traveling at $60\: \mathrm{km/h}$ and ...
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4answers
433 views

Why does Newton's third law exist even in non-inertial reference frames?

While reviewing Newton's laws of motion I came across the statement which says Newton's laws exist only in inertial reference frames except the third one. Why is it like that?
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1answer
422 views

Moment of inertia of rotating particles in center of mass frame?

I am trying to simulate a collision between two molecules. I know the energy for every position/orientation, from which I can calculate the forces. The treatment is classical and the molecules are ...
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2answers
119 views

Drift Speed and Current in Two Different Inertial Frames

We have a long, cylindrical wire carrying a constant current I in an inertial frame. At a distance of R from the center of the wire, the magnitude of magnetic field is $μI/2πR$. What is the magnitude ...
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1answer
114 views

How are fictitious forces related to my feeling?

This question arises when I am studying fictitious forces in an undergrad introduction to physics course. Suppose I am standing in an elevator with an acceleration $a$ directed upward. From the ...
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1answer
219 views

How does Newton's first law asserts the existence of inertial frames? [duplicate]

Recently I've seem here one answer telling that Newton's first law really assures the existence of inertial reference frames. But how is that? I really can't see it. As I know, Newton's first law ...
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4answers
1k views

pendulum is a inertial frame of reference or non inertial frame of reference? [closed]

Example of pendulum is inertial frame of reference or non inertial frame of reference? because if pendulum starts moving its continuously moves without changing there period of time but is changes its ...
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1answer
58 views

Fourier rate equation valid in which frame of reference?

I wonder about the following; the Fourier rate equation of heat conduction states: $$\vec q = -k\nabla T$$ But I'm wondering if this is valid in every frame of reference, because the heat flux $\vec ...
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1answer
163 views

Lorentz Transformation

I have specific questions about Lorentz transformations specifically about length contraction. Why does length contraction only occur in the direction of travel, (not in all directions) when ...
2
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1answer
174 views

From the Poincare group to Minkowski space

In special relativity one assume that spacetime can be locally described by 4 coordinates, so it makes sense to model it as a 4-dimensional manifold. I had the impression that it is assumed that ...
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4answers
164 views

When we talk about speeds in relativity theory, where are they measured?

I recently asked a question here about if the direction we travel matters in relativity theory: Does it matter in which direction I travel in relativity theory? After I got answers and making more ...
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10answers
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What is the Earth truly rotating about/revolving around?

Earth rotates on its axis and revolves around the sun, the sun revolves around the galaxy, the galaxy is also moving. So Earth's net rotation as observed from a fixed inertial frame consists of all ...
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votes
8answers
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Proof that the Earth rotates?

What is the proof, without leaving the Earth, and involving only basic physics, that the earth rotates around its axis? By basic physics I mean the physics that the early physicists must've used to ...
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2answers
292 views

Newton's First Law of Motion; Empirical Aspects

Newton's first law states that in an inertial frame, a body at rest continues to be at rest, and a body in constant rectilinear motion continues its motion, unless an external force is applied upon ...
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0answers
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The definition of Lorentz transformation

I know that the Lorentz transformation, when two frames $\mathcal{S}$ and $\mathcal{S}'$ are in standard configuration (the axes are all parallel to their counterparts in the other inertial frame) is ...
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1answer
123 views

A physical sense of an Inertial frame

Definition clarification needed, please: I am hoping to get physical sense of an "inertial frame". Do inertial reference frames all have zero curvature for their spacetime? So is an inertial frame ...
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3answers
180 views

How to create frame of reference?

Is this possible to create a inertial frame of reference in the earth? How it is possible?
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2answers
133 views

How big is an inertial frame?

How big is an inertial frame? Consider a huge rod which is rotating about a fixed point in a plane, its length is 1 light year. Thus light from its end closer to the fixed point to the end farther ...
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0answers
123 views

Determining Ether Drag - Aberration of Starlight

In order to determine the relative motion between the Earth and the ether (the medium through which light supposedly propagated. It has zero density and complete transparency), scientists used the ...
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0answers
63 views

does a rotating moving body in “flat” space curve its path because of frame dragging?

I am not a physicist. let's say we have a space with an object in it, where all other gravitational bodies are so far away that their affect on the shape of the space is negligible. let's say the ...
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7answers
2k views

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 ...
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2answers
253 views

Inertial Frames of Reference - Description of an Inertial Frame of Reference

An inertial frame of reference is described as being a frame of reference in which the first law of Newton (the law of inertia) holds. This means that all events as described with respect to this ...