Frames Definition and 631 Threads

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 This is a basic question to a kind of complex problem, any help will be deeply appreciatted. I have all the motion equations for the system described below, but i have a problem with the reference frames... So the problem is as follows: A small wind generator is protected...

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...

I have some questions about the TNB frame. The T unit vector is defined this way: \hat{T} = \frac{dr(t)/dt}{ds/dt} = \frac{dr(s(t))}{ds} So, it is parametrized by arc length. Why can't t be left as the parameter? Is this just for definition-of-curvature-sake? If so is there any reason...

I have a question concerning scalar invariance with respect to an accelerating and an inertial reference frame. Here is the problem. Suppose we have a rotating spherical object, which we denote as the rotator, attached to a near-massless wire. The other end of the wire slips loosely over a...

OK, I'm working on a question regarding IRFs, but I seem to be a little confused. Question: Observer A is on the ground and Observer B in on a train moving with uniform velocity v wrt the ground. Each observes that a particle of mass m, initially at rest wrt the train, is acted upon by a...

Hello, I've come up with a simple, imaginary situation that bugs me. Could someone help resolve my confusion? Let's say that a spaceship is traveling through space, and two people- observer 1 and observer 2- are watching it. Both observers can monitor the ship's speed and the amount of fuel in...

I'm not going lie I don't know too much about relativity, though I do understand it. I haven't even gone to college yet and from what I've read so far I'm assuming there's much more to know. Anyway, in most of Einsteins thought experiments he speaks about observations in terms of 1 frame of...

in the definition of inertial frame- a frame in which Newtons law of inertial holds- that a body will continue in its original motion unless impelled to change by a net force my problem is that, how do we know that a force is applied without acceleartion (ie only we conclude there is a force...

[SOLVED] Non-inertial Reference Frames Homework Statement State Newton's Second Law of motion in a non-inertial reference frame. Homework Equations In an inertial frame F=ma If S and S' are two reference frames, the same point is related by r=A(t)r'+b(t) where A is an orthogonal...

i recently posted a question (light and time) someone told me to look into loss of simultanety... according to what i read the speed of light can be judged by someone or things frame of reference.(if I am traveling at .999 the speed of light the light in front of me and coming from behind me...

I’m extracting here a side discussion on the application of Preferred Reference Frames from a thread on the twins paradox, so that thread does not seem to get “hijacked” by this discussion since the connection may seem thin to some. IMO the preferred frame interpretations as used in Astrophysics...

hey :) So, I'm trying to switch between from one frame of reference to another, for a rotation of a 3d object. First of all, the object is rotated, through 2 perpendicular axis. Now, I need to model that rotation in another set of predefined Euler rotations. In other words, imagine a...

Homework Statement A spacecraft with its astronaut has a total mass at rest of 10^5 kg. The astronaut is to travel to a star 10 light years away at a speed such that she only ages 1 year in her frame of reference a) the quantity 1-v/c where v is her speed with respect to Earth is? b)...

Do you think you could give me some helpful insight to a follow up question from the discussion of defining inertial frames: I'm still having trouble figuring out a good way of incorporating parity violation into my intuition. If it wasn't for experiment showing otherwise, I probably would...

i understand the reason and steps leading to the equation that relates acceleration in the inertial frame to acceleration in the rotating frame i.e. a(I) = a(R) + 2(omega)Xv(R) + (omega)X(omega) X r a(I) = acceleration in inertial frame a(R) = acceleration in rotating frame omega =...

Homework Statement A smooth level table is centered on a platform which rotates. - The uniform rotation is at: one revolution in 12 seconds - Two perpendicular lines are drawn through the centre of the table, intersecting a circle of 1.20m radius at points: A', C', B' & D'. - Two men, H'...

lest say you have a man on the moon and one on mars. For them to be in the same frame of ref the only parameters that needs to be common to both is that they must both be traveling at the same velocity and in the same direction yes?

[SOLVED] Help: Length Contraction and changing Frames Hi i have been learning about length contraction and i thought i understand how it works until i was given this question. A very fast train of proper length Lo rushes through a station which has a plaform of length L(<Lo). According to...

I have a very basic question about Special Relativity. I am very limited on my knowledge of physics and math and even more so on SR so please keep that in mind when answering. I have read the basic example many times of two spaceships traveling towards each other with a constant velocity. The...

Homework Statement A particle has a constant acceleration in a laboratory from 0 to 0.5c in 2 seconds. What time elapses for the particle (i.e. what is the proper time for the particle)? Hint You will have to integrate the proper time of the particle over the two seconds as measured in the...

Which of the following statements are true? 1. The index of refraction is the ratio of the vacuum speed of light to the speed inside the medium. 2. The index of refraction is independent of the wavelength of the light. 3. If a light beam is incident perpendicular to the surface of another...

Can someone help clarify this equation from classical dynamics? It doesn't seem to make sense. Here's my textbook's explanation. A particle has position vector \vec{r} in a non-rotating, inertial reference frame (the 'un-prime' frame). Suppose we want to observe the motion of this object in...

Homework Statement here: http://img144.imageshack.us/img144/7518/26700576ok1.gif Homework Equations The Attempt at a Solution well, I tried to solve the motion equation from the inside table. I think there should be a d'elambertian force to the left, and friction force to the...

I seem to be having some trouble processing non-inertial frame homework problems. I hear that sometimes attempting to explain the problem helps with the understanding so here goes. I don't think I have any difficulty visualizing the problems. Creating free body diagrams (FBD) from the...

there are a few things i don't get when it comes to light moving at c from all frames of reference... i mean it makes sense to me in some cases: like if an observer on the Earth sees a missle going one way at half the speed of light, and a spaceship going the other way at the speed of light, the...

A car travels due east with a speed of 35.0 km/h. Raindrops are falling at a constant speed vertically with respect to the Earth. The traces of the rain on the side windows of the car make an angle of 65.0° with the vertical. Find the velocity of the rain with respect to the following reference...

It occurred to me that, as far as calculating the position or movement of objects a reference frame can be rotational, see the http://en.wikipedia.org/wiki/Rotating_reference_frame" . So instead of seeing the Earth as orbiting the sun you could say that the Earth is stationary and the rest of...

in html, i have coded a site with 8 frames i'd say approx, i have a menu with links, when i click on the link i want a page to open in a particular frame, so how do i target it, please give me code, ty btw _self, _blank etc don't work, i think i need to some how name the frames, to open up...

So the homework question is this. In a donut shaped space station that is rotating, what is the force on an astronaut inside the space station (he is on the outside) in both an inertial frame, and the frame of the space station. Intuitively in the frame of the space station the two forces...

I am wondering about the generality of reference frames, and how abstract they can be. Is it possible for a vector in one reference frame to not exist in another frame? Or is there always a relation between two reference frames? Also, are two reference frames like two different sets of...

Hi, everyone: In an effort to show that at any point p in a Riemannian mfld. M there is an orthonormal basis --relatively straightforward--a new question came up: Why aren't the coordinate vector fields always orthonormal?. I know these are orthonormal when M is locally...

Hello all - New to the forums so let me start by saying hi to everyone. ;) Something has always bugged me about considering entanglement effects as "instantaneous." As we all know from SR, moving observers do not agree on simultaneity between two space-separated events. If we...

Hi, everyone: I am trying to show this: Given C(t) a unit-speed curve, using the usual Frenet-Serre frames T,N,B. Define the normal lines to C(t) to be the lines extending N, i.e, line segments containing N. Then: If all normal lines meet at a common point, C(t) must be part of a...

http://img524.imageshack.us/img524/1233/fic06p099kb5.png Ok Here is a frame I have a FINAL comming up and was just wondering IF i had to DISMEMBER frame AG what would be the reactions... like I know there will be Ax and Ay due to a PIN JOINT and Gx and Gy BUT ! -- Since there...

1. http://img225.imageshack.us/img225/8960/fic06p099wf1.png [/URL] Can someone help me dismembering the frame! im confused how to make them on for example ABC http://img257.imageshack.us/img257/5813/68420741vn8.jpg IS that right? i made AG without x and y cause i gues we know...

My problem is related to the Brookhaven experiment of the J/psi discovery and the Y discovery at Fermilab (in both cases, protons over a Berillium fixed target). In both cases they had a resonance decaying into two leptons, and the detecting system consisted of two arms, covering a relatively...