Frame Definition and 1000 Threads

Okay, so this is my first post, and I'm probably going to embarrass myself, but here goes. I have a bunch of questions. So we have an atom, consisting of a proton and electrons, and these electrons spin either clock wise or anti clock wise but in fact appear to do both... until measured...Is...

Homework Statement A frame is made of two firm wires of length ##h## and a rod of length ##l## and mass ##m##. This frame can rotate around horizontal axis in uniform magnetic field ##B##. In a short amount of time ##τ## a current ##I## passes through the frame. What is the maximum angle that...

There is a lot of discussion on this but I still have doubts. Can someone help clarify and point me to correct thread? Object free falls due to gravity (acceleration) so the frame should be non inertial for outside observer. But object does not experience pseudo force in free fall so it may be...

I have a paradox that I don't know the answer to. Special relativity has no preferred frame, but it seems like adding an exponential expansion to space introduces such a frame. The Setup Suppose we're in a universe with a much faster expansion rate, where the space between any two objects...

I know a similar question has been asked but I'm still kind of stumped. Imagine the Earth on the left and a small mass to it's right separated by some distance h. You are in the frame of reference where the Earth and the small mass are moving to your right at some speed v. So, both the Earth...

Problem is here, http://s24.postimg.org/3y6wpyncl/frame.png I'm looking at this problem with the top and bottom beams being separate members and doing a FBD of both separately. However I'm unsure about the points where we have tension/compression. Like at point B, do I include a y component...

I have been reading these notes: http://isites.harvard.edu/fs/docs/icb.topic455971.files/l10.pdf in which they claim that if two spacetime events are coincident in one frame of reference then they are coincident in all inertial frames of reference, thus spacetime events are absolute i.e. they...

Hi all I want to ask a question about NFE(Newtonian Friedmann Equation).I know that NFE is not usefull to describe universe.But we can have a general idea about universe to use that formula. I know that the only spatial coordinate system is CMB referance frame and NFE is derived from...

Lets suppose we have infinitly small particle.And we want to measure the kinetic and potantial energy of particle.Can we use the particle itself a referance frame to calculate this energy ? To clarify my question let's suppose the point position shown by P point and its P(x,y,z) then we want to...

This is problem 11.15 of Jackson, Classical Electrodynamics In a certain reference frame a static, uniform, electric field Eo is parallel to the x axis, and a static, uniform, magnetic induction Bo = 2Eo lies in the xy plane, making an angle theta with the axis. Determine the relative velocity...

Hello, Please: • Assume a universe void of all matter • Visualize 2 parallel paths, 10 meters apart. Let’s call them x and x' • Vessel X is moving along x and vessel X' is moving along x' • Vessel X has a mass of 1 metric ton and vessel X’ has a mass of 2 metric tons • At t0 the...

Hi all, I'm curently meeting the following problem and can't figure it out by myself. Assume we have to vehicles in space, a target and a chaser spacecraft . The target spacecraft defines the RTN frame of reference. Given the position and velocity of the chaser in RTN-coordinates, how can I...

Homework Statement [/B] A conducting square frame of side a and a long straight wire carrying current I and located in the same plane as shown in the figure. The frame moves to the right with a constant velocity v. The emf induced in the frame will be proportional to Homework Equations [/B]...

Homework Statement Show that Newton's Second Law is NOT valid in a reference frame moving past the laboratory frame of problem 1 with a constant acceleration? Problem 1: In a laboratory frame of reference, an observer notes that Newton's Second Law is valid. Show that it is also valid for an...

Homework Statement Show that Newton's Second Law is NOT valid in a reference frame moving past the laboratory frame of problem 1 with a constant acceleration? Problem 1: In a laboratory frame of reference, an observer notes that Newton's Second Law is valid. Show that it is also valid for an...

I have one question which I need to verify as a thought. Suppose I have a particle collider for symmetric energies e^\pm, that give as a result the Y(4S) resonance which later decays in B mesons. Then the lab-frame is equivalent to the rest frame of the e^\pm system and the Y(4S) is at rest in...

Homework Statement https://answers.yahoo.com/question/index?qid=20150607101609AAs8C9t Show that momentum is conserved in a reference frame moving at 10.0 m/s in the direction of the moving car. Homework Equations Mass M for 2000 kg car, Mass m for 1500 kg car. To the observer on the ground...

I know that kinetic energy depends referance frame is there any article about this issue thanks ?

I know that in physics we can change referance frame.The Newtonian Friedmann equation is ##H^2-{8πGp /3}={-k/a^2}## I know that this equation derived from CMB referance frame.Now can we change this referance frame ? (And If you can give me an article about this issue I will be very happy,I...

How is it possible to distinguish a change of coordinate from a change o reference frame? I had this problem while i was studying Rindler' s coordinates: is it only another way to describe a Minkowsky space-time region or does it rappresent a region of the space time as described by an...

Hello I have a question about the meaning of this term "translating frame". Let's consider x-y axis fixed in one place. Now we can construct a unit circle with origin at (0,0). Now I am going to construct another frame of reference with origin at (1,0) (in x-y system). I will let...

I have some question about referance frame 1-Is physics works without referance frame ? 2-Is Space-time itself can be a referance frame ? I mean "Earth speed, relative to arbitary point in space time, is 100.000 km/s" Is this sentence make sense to physics ? Or we need an object to make a...

Dear PF Forum, Sorry if I ask again, because I want a detailed information. Does the universe has a frame of reference? Two twins. A stays, B "travels". (Travel here is confusing, B will say I stay and A travels) and B "turns around" and come back. B ages more slowly then A. Q1: Why? A1...

We all know that in the lab frame observing a charge moving along x-axis, we see an electric field ##E = \frac{Q}{4\pi \epsilon_0 x^2\gamma^2}##, picking up an extra factor of ##\gamma^2## at the bottom. Assuming no external fields are present, what would the charge see in its own rest frame...

For the Godel metric (in Cartesian coordinates), I derived the Einstein tensor Gμν as well as its inverse Gμν in a coordinate basis. I tried converting the inverse into an orthonormal basis using a technique for this that was taught to me on another thread long ago. When I tried using said...

As per theory of special relativity the time in moving frame R' is supposed to run slowly compared to the stationary frame R. But isn't the stationary frame R moving wrt frame R' in the opposite direction. For an observer in stationary frame R', R would be moving with the same velocity wrt to it...

I was given a problem recently that I had to solve and I haven't been able to get a fully satisfactory conceptual grasp of a certain aspect of it. Consider the slowly rotating Kerr solution ##ds^2 = -\alpha^2 dt^2 + \alpha^{-2}dr^2 + r^2d\Omega^2 - \frac{4Ma}{r}\sin^2\theta dt d\phi + O(a^2)##...

If the speed of light is constant in any inertial frame then how do we measure a red shift or blue shift or why?

Hi Friends , I had a discussion with a funny person last night. He said the following argument : Suppose there are 21 objects including the one object under consideration. Each of the 21 objects move with a velocity. Since there are 21 objects, for the object we are considering has 21...

In friedmann equation we start to make a model kinetic energy-potantial energy=U kinetic energy depends observer and referance frame so what's the referance frame and observer in this calculation. Thanks

Dear PF Forum, Again the same question about preferred frame of reference. I have read several threads in Physics forum, but I think this question belong to cosmology. And I have searched in Google and in PF forum threads, so, I'll ask some confirmation here. 1. Does the universe have a...

When I was surfing on a group in Facebook, I found two concepts very difficult to understand by reading the discussions in comments. Those concepts are inertial and non inertial frame of reference. Please make me understand these two concepts in simple words. Please don't suggest links as I...

Homework Statement I am reviewing for my midterm and I just want to quickly understand a concept. It seems that velocity does not depend on the original reference frame. For example, let's say spider man is standing on the ground next to a 78.4 meter tall building, and it is known that if he...

Could someone tell me what exactly is an open reading frame.(ORF) What i know about it is that it starts its sequence with ATG, codes for amino acids and ends with a terminator codon, what does that mean? is it like an mRNA(can't be as it has ##T##) or part of the DNA which will form the...

Homework Statement A wheel of a bicycle weighs 1 kg, all of which is at the rim. The diameter of the wheel is 0.7 m. If the bicycle is ridden at the speed of 3.5 m s–1, then in the frame of reference of the rider: i) Calculate the angular speed ω of the wheel. ii) Calculate the momentum of...

Newton, Poincare, Lorentz and Einstein (around 1921) believed that there is a preferred frame of reference. Einstein changed his mind when he saw that he is going against mainstream. Michaelson Morley experiment and subsequent experiments are regarded by most people as proof that there is no...

Homework Statement Our teacher said we can NEVER do an F=ma problem from an accelerating, or noninertial frame. (He said there are ways to do it, but we can not do it in his class), and I'm confused becuase often times he makes the "system" or makes a "free-body diagram" around an accelerating...

Suppose two people separated by some distance, were simultaneously born in an inertial frame that is moving at some velocity with respect to a stationary frame. For an observer in the stationary frame the two events are not simultaneous. The stationary observer will see one person is born...

I know how to go from ground frame to centre of mass frame by subtracting velocity of centre of mass from the bodies.But I am not sure about how to go from centre of mass to ground frame.I think we should add velocity of centre o f mass.Right?

For any particle P that undergoes a collision in the zero-momentum frame, with the coefficient of restitution being e, I have heard it said that v_{P,f}^* = - e \cdot v_{P,i}^* where vP,f* is the final velocity of particle P in the zero-momentum frame and vP,i* is the initial velocity of...

Hi, I am new here, but there is a question that really bugs me :-(. In Lorentz force why was the velocity defined as relative to the observer and not relative to thesystem generating the magnetic field. By defining it relativ eto the system relativity is not needed to explain how an observer...

I had a though last night that kept me awake trying to figure out what I was trying to understand. I have been out of school many years now so I have forgotten much.. Here is my question. Lets imagine there is a 30 meter diameter hole (complete with a vacuum) in my front yard that goes through...

Homework Statement An inclined plane, fixed to the inside of an elevator, makes a ## 32 ^\circ ## degree angle with the floor. A mass m slides on the plane without friction. What is its acceleration relative to the plane if the elevator accelerates upward at 0.50 g? Homework Equations...

Hi, This is not really a homework problem, but a project I'm working on. So, I am trying to build a Simulink model for my quadcopter. I derived the equations of motion using the Newtown-Euler method in the body frame to get transnational and angular acceleration. For the transnational part, I...

By 'proper frame' of observer O, I mean any reference frame (coordinate system) in which (Condition A:) The worldline of O is always at the spatial origin for every time coordinate. Clearly such a frame is not unique because spatial rotations do not invalidate (A). What I am interested in is...

If an electron-positron is decaying into Higgs and then from Higgs into fermions. What is CM frame in this case? Let us say that electron has momentum $$p_{e^-}=p_1$$ The positron has a momentum $$p_{e^+}=p_2$$ The fermion has momentum $$ p_{f} = q_1$$ and the other one has momentum...

At about 05.30, Dr. Lewin makes a small calculation to find the centripetal acceleration one experiences due to Earth's spin (at the equator). He then says that because of how small the magnitude of this acceleration is, we could consider the Earth's surface to be an inertial reference frame...

Homework Statement I am currently embarking on a project which requires me to design a system where I can transmit voice over a distance, by inputting an analog voice signal on one end and then recovering the voice which I input on the transmitting end at the receiving end. The general design...

I'm studying special relativity for the second time and there's something I think I didn't get since I studied classical mechanics: the idea of a frame of reference. I think the underlying idea is that of a point of view, so that we want to study some phenomenon, but we have to observe it so...

In analysis of frames, we say that "The members of the frames are axially inextensible". In context of frames with vertical legs, what I understand is that the length of the chord joining the member ends in the displaced condition would be same in the axial direction. However, what does it imply...