Frames Definition and 610 Threads

I have a fog in my brain as I am trying to wrap my head around a problem and I am not sure how to word it so I will do my best. If object A is moving near the speed of light but without acceleration then it could be said to be at rest. Measuring a beam of light that passes its position...

suppose we have a moving frame and a rest frame..we know time dilution and length contraction had occurred in moving frame wrt rest frame,this is to make sure that speed of light is same in any frame..but this is not the case..consider measurement of speed of light in moving frame wrt rest frame...

A point mass has a force on it in its rest frame (F). Now go to a frame moving in the +x direction (F'). EM book claims the forces can be related like this: f'_{x'}=f_{x}\\f'_{y'}=\frac{f_{y}}{\gamma}\\f'_{z'}=\frac{f_{z}}{\gamma} I would like to be able to see this with four vectors...

Need help understanding inertial frames of reference! I'm doing an A2 physics unit on special relativity (AQA) and am really confused about this, but I only want to get the idea so don't go to deep please :) I understand that a frame of reference is an area which is fixed relative to...

Ok I'm really trying to understand inertial and non-inertial reference frames, my understanding is as follows: A rest observer on the earth, the observer will be stationary relative to the earth.. Now as I understand it an inertial reference frame is one of which 2 coordinate systems are both...

My question is not homework. I feel ashamed of having this doubts but I'm really stuck on this. The problem is I have a reference frame xyz and here I define the COM \vec x{_{cm}} of the system. Now I move the COM reference frame x'y'z': \vec{x'}=\vec{x}-\vec x{_{cm}} In this reference frame I...

Hi, I have a couple of questions about velocities in inertial and rotating frames of reference, related by the following equation: \mathbf{v_i} \ \stackrel{\mathrm{def}}{=}\ \frac{d\mathbf{r}}{dt} = \left( \frac{d\mathbf{r}}{dt} \right)_{\mathrm{r}} + \boldsymbol\Omega \times...

i know these topics are discussed many times and i have read many of them but still have a doubt. Suppose a car is accelerating and there is an object and a man in the car. Object is ofcourse at rest with respect to man. The man does not know if the car is accelerating or not - he just sees...

Newton's second law of motion is given in Minkowski space by \bar{F}=m(c\gamma\dot{\gamma}, \gamma\dot{\gamma}\tilde{v}+\gamma^{2}\tilde{a}) where \dot{\gamma}=\frac{d\gamma}{dt}=\frac{\gamma^{3}}{c^{2}}\tilde{v}\cdot\tilde{a} and \tilde{v}(t) and \tilde{a}(t) the 3-velocity and...

Homework Statement The distance from Planet X to a nearby star is 12 Light-Years (a light year is the distance light travels in 1 year as measured in the rest frame of Planet X). (A) How fast must a spaceship travel from Planet X to the star in order to reach the star in 7 years...

Is Newton's third law valid in non-inertial frames? For example, in a rotating frame of reference, can Newton's third law still be applied? Or does the non-inertial character of the frame violate it?

°Homework Statement A pilot wishes to fly to city A, 800km north of the present location. The plane is capable of an air velocity of 300km/h. There is a wind blowing 120 km/h [S40°W] a) if she flies directly to city A, what will be her observed ground velocity? b) what should her orignal...

Hello All, The following may be a simple problem. But, your thoughts will be very much appreciated. Homework Statement Let's use a gun with mass m1 and a bullet m2. The bullet is fired in the positive direction with speed v2, and the gun recoils in the negative direction with speed v1...

Homework Statement A 20g ball of clay is shot to the right at 12m/s toward a 40g ball of clay at rest. The two balls of clay collide and stick together. Call this reference frame S. Homework Equations What is the velocity of a reference frame S' in which the total momentum is zero...

Hello, I am having difficulty understanding the concept of Newton's first law only applying in an inertial reference frame, or a frame that is at constant velocity, however, apparently the 1st law no longer applies if the reference frame is accelerating. Can anyone give me some sort of concrete...

Howdy folks Pardon any implicit or explicit stupidity in advance. I'm an EE major taking a class in Autodesk Inventor, and I'm probably going to do a motorcycle frame for a midterm project. While it will not be required, I'm curious to see if I can make something roadworthy. Does any...

Hi folks, I asked a form of this question in another forum and didn't get a satisfying answer. As I understand it, there is a time in the early universe (t < 10–12 s) when particles have not acquired mass. According to special relativity, massless particles travel at c. Also according to...

Homework Statement I a little lost on how to use the relativistic velocity addition formula to determine the increase in speed "v" over a short time interval in the Earths frame of reference, for a rocket having left Earth at rest and traveling through space accelerating at constant acc. of...

Hello. Is there a way, as for the energy frame, to get the particle frame 4-velocity of a fluid from its energy-momentum tensor?

Would it be fair to describe the Unruh effect by saying that from the perspective of an accelerated observer, some virtual particles in an inertial frame become real particles in the accelerated frame? Wald talks about how the appropriate transformations between inertial and accelerated...

The initial presentation of Newton’s Laws of Motion (NLM) to students often proceeds as follow: 1. The 3 laws are presented, 2. The caveat that the laws are only valid in Inertial Reference Frames (IRFs) is (sheepishly) mentioned, 3. An attempt is made to define an IRF, and 4. Some examples...

As I understand in SR light is always c in it's local reference frame regardless of a present gravitational field. Light would appear to be traveling slightly less than c in a gravitational field otherwise known as the Sharpio Delay in all non-local reference frames. Now, light must be traveling...

As a result of observations made over many, many years, physicists have inferred that: "No experimental test provides any way to distinguish an inertial frame from another." This negative form of the statement is important, as it is a prediction which can be tested experimentally and thus...

The interval between two events ds^2 = -(cdt)^2 + x^2 + y^2 + z^2 is invariant in inertial frames. I was wondering, if this same interval still applies and is invariant in non-inertial frames?

Homework Statement Do objects same kinetic energy in all inertial reference frames? For objects interacting, is energy conserved in all inertial reference frames? Homework Equations None The Attempt at a Solution I think the answers are No for the first one, and Yes for the...

In a 1925 paper, Erwin Schrödinger mentions that "our inertial systems are free of rotation precisely with respect to our stellar system", instead of being "anchored...in much more distant stellar masses". Is this really the case? If so, this suggests that the total gravitational potential...

I am re-posting this question here in a new thread as Humber mistakenly posted it in a two year old thread.

When 2 objects A,B are moving wrt to each other (lets say @0.86c)then from frame A if local time is 10 years then time at B is 5 years. What does this mean?is it any event happening now in A(10 years) is simultaneous with the events happened in B when its clock ticked 5 years?

Is it possible for a particle to exist according to one reference frame and simultaneously not exist according to another? If energy is relative, can a collision between two particles have enough energy to produce new particles according to its own reference frame but not have said amount of...

Homework Statement Using the transform of the electromagnetic tensor F between frames, F'=RFR^{T} verify that: i) the perpendicular component of the magnetic field in the frame, S', moving with velocity v with respect to the frame S, can be found from the transform of B_{\bot} in S...

i came over the terms 'inertial' and 'non-inertial' frames during the study of rotational motion...pls clarify the difference...! plus can anyone give me a link from where i can practice numericals of angular momentum, moment of inertia, torque..

I've been lurking on PF for awhile now, but I reckon I'd benefit by actually trying to participate in the discussion and by asking my own questions once in awhile so, Hi all! In my second year I took a module on Classical Mechanics, and one of the things we covered was the Coriolis Theorem...

What makes the three mechanical objects Truss members, beams, and frames having different characteristics related to force systems. Example truss members only exhibit tension and compressional forces, that's different from others.

I can't manage to understand the quasi-schizofrenic way we should believe that our universe started at a certain time point called Big-bang while at the same we must never admit that in order to say that it follows that an absolute time (and an absolute frame) must be distinguished, (the CMB...

Does the temperature a body depend on its frame of reference? Does the internal kinetic energy depend on frame of reference? In short does it depend on velocity of body at relativistic velocities? the body doesn't know it is moving at that velocity,so i think temperature must not depend on...

New Video on "One trillion frames per second camera" Here is the video: Mods, please delete if there is already a thread for this. I think this is a great achievement by the researchers. It's an interesting topic, so maybe people can use it to ask questions on how/why it works, and...

Post any thoughts or ideas here.

If you have a particle, and you know its rest mass is about 100 Mev/c^2 and in the lab frame you measure it to travel at (8/9)^1/2 c then what is its energy in the rest frame?? Would it be just 100MeV? or 300 MeV due to the relativistic constant? i don't really know how you would reason out the...

The speed of light, the term "light year", and reference frames. Hi everyone. This is my first post, and I post out of desperation. A friend of mine and I were casually discussing Time Dilation, interstellar travel, etc. when we came to a point we fundamentally disagreed upon. Neither of us...

Hello I know that it's possible to reformulate Newtonian mechanics in such a manner that absolute velocities of objects can be defined. By absolute I mean defined without any reference to a specific frame of reference (just as in the article Notes on Mathematical Physics for Mathematicians)...

I wanted to understand something about Inertial frames especially as they are talked about in SR. It appears that the laws of physics should hold the same in them. Now I understand that inertial frames only involve things moving relative to each other and moving in constant speed so you can...

Homework Statement Essentially, a particle is moving downward from the top of a tower at 0.98c, and the tower is moving up at 0.98c. I am to find the apparent height of the tower from the perspective of the particle Homework Equations Δx=γ(Δx′+vΔt′) Δt=γ(Δt′+vΔx′/c2)...

The first law of motion says that it takes force to accelerate something. The second law of motion says that F=ma. So now my teacher says that the first law is for inertial reference frames, while the second is for non-inertial reference frames. This really annoys me because I don't...

If one wants to calculate the elapsed time from the perspective of an object A moving at velocity, v, for time, t, relative to a stationary object B, all you have to do is calculate: \int_{t_o}^{t_f}\frac{t}{\gamma} Of course, \gamma has no dependence on t because v is constant, so we get...

We all know the definition of a rope between two identical accelerating spaceships and how that rope will break assuming they both accelerate with the identical same velocity (as defined from a observer on Earth for example). And it makes sense, thinking of stress. But how do I define a Lorentz...

a frame of reference is moving with a constant velocity with respect to a inertial frame of reference,then moving frame will be inertial itself?

Hello there I have 2 questions: 1. Can one change the coordinate system of torque vectors through a homogeneous transformation matrix with both rotation and displacement? 2. What's the procedure to add two torque vectors about different axes? Thanks in advance, João

An inertial frame is one which is not accelerating. i.e if I'm sitting in an accelerating bus or plane I'm not an inertial observer however if I am in a bus or train traveling at a constant velocity i.e zero acceleration then I am an inertial observer. One thing Id like to ask here is that...

Homework Statement Challenge: a rather eccentric group of astronomy students wanted to celebrate the impact of the Shoemaker-Levy comet on Jupiter by holding a party of sufficiently long duration that their celebrations were simultaneous with the impact of the comet in all inertial reference...