Frames Definition and 610 Threads

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...

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 =...

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...

Homework Statement There is a planet of mass m_1 orbiting a star of mass m_2. One question is "What is the semimajor axis of the planet's orbit in the coordinate system centered at the star's center", and another is "What is the semimajor axis of the planet's orbit centered at the center of...

Hi, My question probably has a simple answer, but I've been scratching my head over it a little too long so I thought I would ask it here. I have three initial photons involved in a collision with 4-momenta k1, k2 and k3. I have two reference frames: frame 1: the centre of mass frame of...

1. The Question Verbatim "A pilot starting from Athens, New York, wishes to fly to Sparta, New York, which is 320 km from Athens in the direction 20.0 N of E (LETS CALL THIS VECTOR = A). The pilot heads directly for Sparta and flies at an airspeed of 160km/h. After flying 2.0 h, the pilot...

edit: this problem is about energy discrepancies when changing frames and is no homework. suppose I accelerate a car from 0 to 100. the energy difference is 1/2 m v^2 - 0 = 1/2 m 100^2 = 5000 m joules now I accelerate another car from 0 to 50. the energy difference is 1/2 m v^2 - 0 = 1250 m...

Homework Statement Two events happen at the same point x'(0) in frame S' at t(1)' and t(2)' a) Use equations x=gamma*(x'+vt') and t=gamma*(t'+vx'/c^2) to show in frame S the time interval between the events is greater than t(2)'-t(1)' by a factor of gamma Homework Equations The...

Homework Statement Consider a head-on, elastic collision between two bodies whose masses are m and M, with m << M. It is well known that if m has speed v0 and M is initially at rest, m will bounce straight back with its speed unchanged, while M will remain at rest (to an excellent...

This is the question: A physics lecture demonstration uses a small canon mounted on a cart that moves at constant velocity v across the floor. At what angle theta should the cannon point (measured from the horizontal floor of the cart) if the cannonball is to land back in the mouth of the...

In the link: that I found here 5 minutes ago ( thanks for the link ) there are two drawings: the first and the second. In the first the link explains that there is a magnetic field, because the - charges are moving. In the second the link explains that there is not a magnetic field...

Hey all, I made a post earlier today on gravitational time dilation. It got me thinking that in any accelerated frame of reference there must also be a time dilation, due to the equivalence principle. This can simply be a elevator accelerating through space or it can be caused by centripetal...

Do accelerated observers also see the same constant speed of light as inertial observers? How do we transform to an accelerated frame? For simplicity, I mean a constant acceleration, constant in direction and magnitude. By acceleration I mean the second derivative with respect to lab time...

In an anniversary celebration of Marilyn Bell's 1954 crossing of Lake Ontario a swimmer set out from the shores of New York and maintained a velocity of 4m/s [N]. As the swimmer approached the Ontario shore, she encountered a cross current of 2m/s [E 25deg S]. Find her velocity with respect to...

I enjoy a good space opera and have always wanted to write my own, but at the heart of most space operas, even the relatively “hard” sci-fi ones, lurks the FTL drive. Plots just don’t advance well without them. But if relativity is correct, then FTL is the same thing as time travel, which leads...

Hello everybody ! This is my question: Suppose you have a mass m0 inside an ellipse (at rest). Suposse someone see it from another frame, from this frame he will see the ellipse contracted. I know there's no black hole, but, how can explain our observer this result? I'm trying to see only...

R' is an observer from I'. A rod is in a state of rest relative to him. He measures its proper length L(0). An observer R from I measures its Lorentz contracted length L related by L=L(0)sqrt(1-vv/cc) (1). If we reverse the situation, R measuring the proper length of the rod R' measuring its...

Some Inertial Frames may be more Equivalent than Others Silly proposition - but take the peculiar results predicted by Einstein in Part IV of the 1905 paper with a little extra added. We place two clocks at locations A and B separated by a great distance L. We identify A clock with an S'...

If paintings were not put in rectangular frames but in triangular or hexagonal or circular frames what difference would this make to the end product? Would the artist be forced to think differently?When the Romans came to the United Kingdom in the first century AD they brought the idea of right...

Homework Statement A rubber stopper of mass 25g is suspended by string from a handrail of a subway car traveling directly eastward. As the subway train nears a station, it begins to slow down, causing the stopper and string to hang at an angle of 13 degrees from the vertical. What is the...

so here r ma doubts => it is sometimes heard tat inertial frame of referance is only an ideal concept and no such inertial frame exists.comment. =>the accelaration of a particle is zero as measured from an inertial frame of referance . can we conclude tat no force acts on it? => a...

Suppose event A causes event B. To one observer, event A comes before event B. Is it possible that in another frame of reference event B could come before event A? If so, how?