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

learn more… | top users | synonyms

0
votes
1answer
56 views

Proving the conservation of 4-momentum for a particle collision $A+B\to C+D$

Let me say that particle A hits particle B and two particles come out - C and D; In system S I can write: $$p_A^μ+p_B^μ=p_C^μ+p_D^μ;\tag{1}$$ here $p_N^μ$ is the 4-momentum. Using the Lorentz ...
0
votes
3answers
75 views

How does an electromagnetic field oscillate if time does not pass for the speed of light?

As far as I'm aware, traveling at $c$ will prevent time passing due to time dilation. Electromagnetic waves rely upon oscillations to propagate. Since oscillations rely upon the passing of time, how ...
-1
votes
1answer
34 views

Relativity and Transformations [closed]

Show that if we transform first in the $x$-direction and then in the minus $x$ direction with the same speed $v$, we end up with the original space-time coordinates. Note: For this problem you ...
2
votes
1answer
88 views

About the relativistic wagon simultaneity problem

I'm getting utterly confused with this problem. The situation is basically to know what events to take in one frame in order to see them synchronized in another. I sketched the situation as this: ...
2
votes
2answers
73 views

Deriving the equations for a moving inertial reference frame [closed]

I assume $c=1$ in the following derivation: In order to derive the equations for a moving inertial reference frame, I immediately wrote down the following: $$ x'=Ax+Bt, \tag{1}$$ $$t'= Dx+Et. ...
0
votes
2answers
161 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 ...
1
vote
3answers
107 views

Does the Earth revolve around the Sun?

I am aware of this Phys.SE question: Why do we say that the earth moves around the sun? but I don't think this is a duplicate. In a binary star system, where the masses of the 2 stars are not so ...
2
votes
4answers
377 views

What is the universal speed limit relative to? [duplicate]

If all speeds are relative, then what "governing" force is that speed limit relative to? Is there some sort of fixed or absolute grid with locations everything is compared to? Does this also mean ...
14
votes
2answers
3k views

Deriving the Lagrangian for a free particle

I'm a newbie in physics. Sorry, if the following questions are dumb. I began reading "Mechanics" by Landau and Lifshitz recently and hit a few roadblocks right away. Proving that a free particle ...
0
votes
1answer
25 views

Who is moving and with who's relation?

What if we are in a cube of 3×3 m  which is further enclosed in a sphere of radius 50 m? And the sphere start to rotate on its own axis would we experience force? If not then what happens if there is ...
1
vote
1answer
72 views

Elastic Collisions and Relative Velocities

In a 1D elastic collision, it is well-known that the relative velocities of the two objects (before and after the collision) are reversed. What is the extension of this result to 2D or higher? Is ...
1
vote
1answer
59 views

Inertial and Non-inertial frames of reference

I'm really beginner in physics and I recently started to study the concept of frames of reference, inertial and non-inertial ones. In the end, I thought I had understood it: frames of reference ...
0
votes
1answer
58 views

Confusion about Weinberg's discussion of equivalence principle. Help understanding formula

I am reading Steven Weinberg's book Gravitation and Cosmology. On pages 67-68, he begins his discussion of the Principle of Equivalence of Gravitation and Indertia by saying the following: The ...
1
vote
5answers
271 views

Is the polar coordinate system non-inertial or inertial?

Consider a car driving around in a circle lying in the plane and suppose we were interested in determining its acceleration as measured by an observer stationary on the "ground" or whatever. ...
8
votes
7answers
354 views

What does the statement “the laws of physics are invariant” mean?

In the first paragraph of Wikipedia's article on special relativity, it states one of the assumptions of special relativity is the laws of physics are invariant (i.e., identical) in all inertial ...
0
votes
0answers
36 views

Forward and Behind Frames of Reference

It's my understanding that light travels at the same speed in all inertial frames of reference. Suppose there's a small train car 5 feet long (at our rest point of view) traveling at a constant speed ...
4
votes
1answer
78 views

Uniqueness of the equivalence class of inertial frames

Let us define an inertial frame as a frame of reference where the laws of physics take their usual form, as opposed to non intertial frames where one has to introduce pseudo-forces. We can further ...
0
votes
4answers
88 views

Absolute (as opposed to relative) concept of inertial frame

In mechanics there is a relative concept of "inertial frame": frame A is inertial with respect to frame B if A moves uniformly with respect B. That concept is easy to understand. There also seems to ...
11
votes
5answers
1k views

If the solar system is a non-inertial frame, why can Newton's Laws predict motion?

Since there is no object in the universe that doesn't move, and the solar system likely accelerates through space, how did Newton's Laws work so well? Didn't he assume that the sun is the ...
3
votes
0answers
46 views

Does relativistic glider violate principle of equivalence?

The relativistic glider proposed can slow down the fall of an object in gravitational field. Will this violate the principle of equivalence which says that one cannot distinguish between free falling ...
0
votes
1answer
32 views

Time difference between two moving inertial frames of reference [closed]

This is a question I am trying to solve: Let S and S' be two inertial frames of reference and S' is moving relative to S at a velocity of 0.6c. When x = x' = 0, t = t' = 0. At t = 2 x 10-7 s, an ...
1
vote
0answers
37 views

Galilean and Lorentz Covariance in Julian Schwinger's book Electrodynamics

In the book Electrodynamics (pp. 8-11) Julian Schwinger "derives" (in this special case) the complete Maxwell equations from the Coulomb potential using only the Galilean transformation $$ ...
1
vote
3answers
148 views

Why does the Michleson-Morley experiment only contradict the aether?

This question is related to Validity of Maxwell's equations with no aether or relativity? (so please read this first). In this question, the answers seem to suggest that getting rid of the aether ...
0
votes
3answers
256 views

3 inertial frames compared in STR

Suppose an event is observed in 3 inertial frames K, K' and K''. The coordinates in K are $(x,t)$ in K' are $(x',t')$ in K'' are $(x'',t'')$. The K' and K'' coordinates are then Lorentz-transformed to ...
1
vote
4answers
84 views

Which one is inertial frame?

I'd like to ask a question which made me confused. I think that, e.g., a man falling to earth could think himself as stationary and the Earth as accelerating towards him. But I, as an observer, I ...
4
votes
3answers
368 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 ...
2
votes
3answers
257 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 ...
1
vote
1answer
108 views

If reality is relative, then what about Newton's bucket argument?

There is nothing outside the universe. - Lee Smolin So, there can't be any absolute frame. Everything must be measured relative to an entity that exists in the universe. Thus, space ...
13
votes
5answers
2k views

Newton's Bucket

Newton's Bucket This thought experiment is originally due to Sir Isaac Newton. We have a sphere of water floating freely in an opaque box in intergalactic space, held together by surface tension and ...
19
votes
7answers
4k views

Why does rotation simulate gravity if motion is relative?

In Einstein's theory of relativity, if motion is truly relative, then why would somebody in a rotating space station experience (artificial) gravity? I mean, I get why they experience gravity IF the ...
1
vote
1answer
34 views

Specific scenario involving rotation and inertial frames of reference?

We recently went over some rotational motion in my freshman physics class, I had a question for the professor on your frame of reference, and how that would effect the rotation of the object. Say you ...
0
votes
0answers
68 views

Relative acceleration: frame of references

There is a question I've been struggling with, and I ask for your help to understand it fully. Q: An inclined plane, fixed to the inside of an elevvator, makes a 32 degrees angle with the floor. A ...
0
votes
2answers
110 views

Who plays the role of centrifugal force in an inertial frame of reference?

It is noteworthy to quote a sentence from my book, It is a misconception among the beginners that centrifugal force acts on a particle in order to make the particle go on a circle. Centrifugal ...
4
votes
6answers
2k views

Measuring speed of the moving train, if I'm inside it

So I am inside a coach in a train that is fully sealed (with no windows and a locked door). I have a torch, photo & time sensor and a scale with me. So, I place the sensor at one of the walls and ...
1
vote
0answers
52 views

Two referential frames. An ant is moving on a uniformly rotating disk and appears not to be moving relative to the disk [closed]

They want us to find the Coriolis and centripetal acceleration. My problem is drawing the referential. Because, there are 2 referential frames. The inertial one would be the disk right, with 3 axes, ...
0
votes
3answers
212 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 ...
8
votes
5answers
2k views

Is acceleration relative?

A while back in my Dynamics & Relativity lectures my lecturer mentioned that an object need not be accelerating relative to anything - he said it makes sense for an object to just be accelerating. ...
0
votes
0answers
45 views

In the formula for the change of frame of reference, which term(s) is/are the centrifugal/centripetal acceleration?

This is the formula for the change of frame of reference for the acceleration: I have a book where it is written that: The first term is the absolute acceleration. The second term is the relative ...
2
votes
1answer
527 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 ...
2
votes
0answers
81 views

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 ...
7
votes
4answers
2k views

Second law of Newton for variable mass systems

Frequently I see the expression $$F = \frac{dp}{dt} = \frac{d}{dt}(mv) = \frac{dm}{dt}v + ma,$$ which can be applied to variable mass systems. But I'm wondering if this derivation is correct, ...
14
votes
5answers
2k 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 ...
1
vote
1answer
99 views

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 ...
26
votes
14answers
7k views

Why do we say that the earth moves around the sun?

In history we are taught that the Catholic Church was wrong, because the Sun does not move around the Earth, instead the Earth moves around the Sun. But then in physics we learn that movement is ...
3
votes
2answers
151 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 ...
0
votes
1answer
181 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 ...
5
votes
4answers
632 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?
0
votes
2answers
88 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 ...
16
votes
15answers
3k views

What are the mechanics by which Time Dilation and Length Contraction occur?

What are the mechanics of time dilation and length contraction? Going beyond the mathematical equations involving light and the "speed limit of the universe", what is observed is merely a phenomenon ...
1
vote
2answers
182 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 ...