Frames Definition and 610 Threads

Hello... learning to post and into the appropriate forums. Also, can you delete previous post and how? Quick question: Since time as we know it does not or can not 'stop'... Is there such a thing as an intertial frame at 'absolute rest'? Thank you for any and all responses. Bye G

I've got a problem understanding a line of proof in my lecture notes. Given that you have a charge of +Q and mass m orbiting a fixed particle of charge -Q' in the presence of a magnetic field B. The particle is moving slowly enough for relativistic effects to be ignored. Given that...

Two massive lead balls are sprayed with a thin veneer of positive charge. They are isolated and at rest in inertial frame K. The positive charge is such that the electrostatic force of repulsion exactly cancels the gravitational force of attraction. Viewed from frame K’, the Lorentz force on...

Here's a question that's bothered me for a while. Suppose you are a person (P) at point A. You travel between point A and B at some fraction of c (speed of light). And so relativity kicks in. Now, that's the standard relativity model and we talk about P with regard to A and B. Now, what...

Homework Statement Given Cartesian coordinates x, y, and polar coordinates r, phi, such that r=\sqrt{x^2+y^2}, \phi = atan(x/y) or x=r sin(\phi), y=r cos(\phi) (yes, phi is defined differently then you're used to) I need to find \frac{d\phi}{dr} in terms of \frac{dy}{dx} Homework...

Hey! So, as I understand, kinetic energy of a moving object is proportional to its velocity squared. So I'm wondering where these inconsistencies come from, and how they are resolved: So, say two objects of mass M are travelling, with reference to a stationary observer, one in the left...

How does the principle of "Reference Frames" work? What would be an appropriate answer for that statement? I can't think of anything fitting, also I'm not too educated in that subject. Any help is greatly appreciated. :)

When an object is thrown by someone standing on top of a moving train, which variations of "frames of reference" would apply? (i.e. inertial, non-inertial, etc.) How would this principle work? (The object would go the same relative distance as it would if thrown from a person standing on...

Hi! I have the following problem: Example: collision of 2 electrons For non-relativistic scattering it is easy to show that the speed of the CM frame with respect to the lab frame is equal to the speed of the electrons in the CM frame, expoloiting the fact that in the lab frame, one of the...

Homework Statement This is an example problem from the book. However, I have absolutely no clue how they solved it. I cannot follow their logic. If someone can just solve it and explain it for me lucidly step by step, I would really appreciate it. Here it is: "A bicycle travels with...

So, for example, 2 objects are moving towards each other. There is a frame where 2 object move with (for the sake of simplicity thy both move with the same velocity) the velocity V Then there is a frame where one of the object stand still, but the other moves towards it with the velocity 2V...

2 textbooks I have give postulate 2 of SR as: "The speed of light in vacuum is constant in all inertial reference frames". But "Classical Dynamics" by Jerry B. Marion has: "The velocity of light in free space is a universal constant independent of any relative motion of the source and...

SR "Reference Frames" in QM ? The SR concept of “Reference Frame” cannot be transferred to the micro-world of QM because, due to the HUP, space and time are blurry in that world. Comments? (Thanks in advance).

Afternoon, I'm studying Engineering Dynamics (4th Year Undergraduate) and I was wondering if anyone can point me to a resource with regards to rotating reference frames and vector notation? The notes I've been given aren't particularly helpful. Much appreciated.

Homework Statement A boat goes at 7.78 m/s [37 degrees west of south] in a current of 2.41 m/s [5 degrees north of west]. Find the velocity compared to the bottom. Homework Equations I think we use this: Vf2 = Vi2 + 2a x delta d The Attempt at a Solution I drew a diagram but...

Hello, I am stuck on the coriolis force. If an object is dropped how do I get the eastward deflection when looking from an inertial frame? I know how from the rotating frame but for some reason I am stuck, i.e. what terms to use. Also, if I throw a ball straight up from Earth what is the...

I have read before that when color television was developed the frame rate was changed from 30 frames per second to 29.97 frames per second to avoid some kind of problem with the circuitry, but I have never seen an explanation of just what this technical problem was. My somewhat educated guess...

Is there really such a thing as an inertial frame? How would we know for sure if we were in one? Looking at space, things are moving and accelerating all over the place, it would seem impossible to tell whether a frame is really inertial or not. Imagine you are in space and everything around...

Here is an interesting question (units are Gaussian): An infinitely long strgiht wire of negligible corss-sectional area is at rest and has a uniform lineare charge density q_0 in the inertial fram K'. The frame K' (and the wire) move with a velocity v parallel to the direction of the wire...

Simple question. I would like to know if there is a definitive answer , consensus in the field, on the question of the measurement of light in an accelerating system. Whether one way measurements from the front to the back and vice versa would result in (c +v) = (c-v) = c as usual...

What if i was traveling in a car with an e- with me. W.r.t to a positive charge at rest , it would seem accelerating to me i.e. it would have a magnetic field but acc. to a person on the ground it would just have an electric field. If there were a car moving relative to me , the person would...

In Newtonian physics gravity is a force and in relativity it's curved spacetime if I understand it correctly. So my question is, does the gravitational field of an object look different to different observers? What I mean is, does one reference frame see the strength of the field to be greater...

So, here is the situation: One starts with 2 protons, they collide and one ends up with 3 protons and an antiproton. How much energy will you need to do this? Upon inspection, it seems you will just need 2mc^{2} in kinetic energy to create 2 new proton-massed particles. This is wrong I...

I am reading The Elegant Universe...and I have bumped to possibly the first part of the book that I can not understand. When an electron and a positron pop out of existence, they soon annihilate each other with a "bang"...emitting a photon. If fundamental substance of universe are...

Here's a statement that I'm supposed to solve: (\Deltax')2 = (\Deltax)2 - c2(\Deltat)2 And the accompanying text: "Show that (the equation above) is the same for all reference frames in special relativity" I consider myself somewhat decent with your basic special relativity calculations...

Homework Statement I am aving a bit of trouble understanding how to show something is a 4 vector. For example K = (v/c, 1/lamdba, 0, 0 ) Show it is a 4-vector. I am not quite sure how to start this. Similarly I have the amplitude of a wave in frame S described as A=cos[2PI(vt-x/lambda)] and...

Im trying to understand frames of reference, I am very new to relativity so sorry if I am being silly! Suppose you have a 2 spacecraft one traveling relative to the sun, and the other traveling relative to the first spacecraft in a perpendicualar direction. i know the velocitys of...

Homework Statement Show that the primed frame corresponds to a 'rocket' frame moving at speed v in the x direction relative to the unprimed frame. Variables: x, x', t, t', y, y', z, z' Homework Equations ct' = γct - βγx x' = γx - βγct y' = y z' = z The Attempt at a Solution...

something which seems so fundamental that i can't find anywhere that derives it is the following: E' = gamma * (E - p.v) where E is the energy in one frame, p the momentum, v the relative velocity of the other frame, and E' the energy in the other frame. i.e. energy transforms like...

Does the CMB allow special "almost" rest frames to be defined? In this sense, use a rocket to put yourself in a frame of reference such that in this frame observations of the CMB would average to zero (average over photon momentum) over your celestial sphere. In such a rest frame is the total...

[b]1. Suppose the space time co-ordinates of two events in inertial frame S are as follows: Event 1: x1=x0, t1=x0/c y1=z1=0 Event 2: x2=2x0, t2= x0/2c y2=z2=0 Show that there exists an inertial frame s' in which these events occur at the same time (i.e t1'=t2') and find the value of time...

A professor told me that in our spacetime we are able to distinguish between different inertial frames because the cosmic microwave background looks different. If this is true then what spacetime do we live in? What would it look like mathematically. Would the det(g) not be negative?

Homework Statement We have two frames of reference: K (x,y,t) and K' (x',y',t') such that initially x=x'=y=y'=t=t'=0. Now let K' move with a velocity \vec{v} = v [\tfrac{1}{\sqrt{2}},\tfrac{1}{\sqrt{2}}] Write Lorentz transformations in such a case. Homework Equations The Attempt at...

Homework Statement A 2000-kg car moving with a speed of 20 m/s collides with and sticks to a 1500-kg car at rest. Show that because momentum is conserved in the rest frame, momentum is also conserved in a reference frame moving with a speed of 10 m/s in the direction of the moving car...

Hi, everyone:) In my mechanics book a derivation is given for acceleration in rotating reference frames. However, there is one step I don't understand. First of all, it is derived that v=v'+\omega\times r' or \left( \frac{dr}{dt}\right) _{fixed}=\left( \frac{dr'}{dt}\right) _{rot}+\omega\times...

I keep hearing how motion only exists relative to something else. But what if there is some object in space, and it is the only object in the universe. It has some kind of propulsion system, and it activates it, goes to a certain speed, then stops accelerating. Is that object really moving, or...

the pin-jointed frame is 60/30 degrees triangle with suport points at the vertical wall being 0.45m apart and the lower frame member being horizantal. if the hanging load is 6kg . culculate the foeces in two frame members and also the reactions at the wall supports.

Greetings and happy new year to all members in here. This is my first post in the physics forum. Does anyone know what sort of materials are commonly used to make the steelframes of car? I am guessing it's some form of steel, but which? And why the choice? For illustration, the link...

I have a question about Newton's Second Law and Inertial Frames of Refrence. It is canon that Newton's Second Law is only applicable in an inertial frame of refrence. Newton's Second Law is the net force acting on a body is equal to the time rate of change of the body's linear momentum...

It is sometimes heard that inertial frame of reference does not actually exists and is only an ideal concept. What do you guys think? Say, for example, An object is placed far away from all objects that can exert force on it. A reference frame is taken by taking the origin and axes fix in...

Homework Statement Two 10-inch diameter pipes (pipe 1 and pipe2) are supported every 10ft by a small frame like the one shown. Knowing that the combined weight per unit length of each pipe and its contents is 22 lb/ft and assuming frictionless surfaces, determine the components of the reactions...

Hi all. I was trying to imagine gravitation as a causal effect of time dilation and have relatively little schooling so... With frames of reference obviously a high degree of time dilation is attained with a relative velocity close to c. however I understand a large stellar object such as a...

Homework Statement I am a bit confused about what are inertial reference frames and what is not. The text states: "We define an inertial reference frame as a reference frame in which Newton's laws are valid... Accelerating reference frames are not inertial reference frames...

Hi, I am a bit confused about a certain aspect of Special Relativity and I am hoping someone can clear this up for me. Let's say we have an event and two observers. Observer A stands a few meters from the event, Observer B is hundreds of thousands of miles from it. Relative to the event and...

i've just had this thing running through my head that I'm trying to resolve: 1. two parallel wires that conduct a current (same charge carriers) will attract one another, that is the magnetic force each wire emits due to the flowing current will induce an attractive force in the other (charge...

Homework Statement Ted and Mary are playing a game of catch in frame S', which is moving at 0.600c with respect to frame S, while Jim, at rest in frame S, watches the action. Ted throws the ball to Mary at 0.800c (according to Ted) and their separation (measured in S') is 1.8*1012m. According...

This might be a dumb question to ask, but does anyone ever worry about reference frames in QM? I'm just starting my first course and don't know much yet, but it seems like if we can consider operators to be vector fields (reference to my previous post) then we might have to worry about groups of...

I picture two reference frames for two different objects moving relative to each other as two coordinate spaces S and S'. My question is, say both spaces start of on top of each other (ie both objects are initially stationary) and then the objects start moving relative to each other, would the...

Hi guys, I initially posted this here ... https://www.physicsforums.com/showthread.php?p=1871724#post1871724 ... but I see by the forum rules I should have posted it independently. First of all, am I correct in understanding that a) it is impossible for an observer to observe...

Hello gurus, I have a mental experiment that I'm wrangling with. Assume for a moment that two craft (Ship A and Ship B) are approaching each other at a significant fraction of c. Let us also assume that I, the observer, am in a stationary craft a large distance away rotating with the plane...