Frame Definition and 1000 Threads

Hi. I'm a sophomore level undergrad trying to understand General Relativity (and all of physics for that matter) with the currently insufficient tools I possess. I was reading Einstein's book, "Relativity", and when I came to the section that describes gravity as the apparent force that arises...

Homework Statement To rods, each with mass 0.3 kg and length 0.2 m, are welded together at one of their ends, so they form an L-shaped frame. A ball with mass 0.3 kg and with speed 5 m/s hits one of the rods at its end at an angle of 0 degrees (so ball speed vector is perpendicular to one...

A 3 pin frame ABCDE is supported at A and E. it supports vertical loads of 60 kN at B 80 kN at c and 100 kN at D as well as a horizontal UDL of 50kNm along DE. Calculate the reaction forces. I have REV = 124 kN and RAV = 116 kN. REH = 115.3kN and RAH = 215.3 kN. Are these correct Next...

***not homework for any class*** Title: "Preserving Magnetic Polarity in a Revolving Reference Frame" Problem: How can a revolving reference frame (assuming an uncharged observer with negligible mass) observe the same polarity for a magnet in the case where the rotational speed is great enough...

Hello, apologies if this has been asked before but I couldn't find it upon searching... My block to understanding general relativity has always been how the idea of gravity being the same as an accelerating frame leads to a a curved space-time? What about the fact of not knowing whether...

Hi i have a problem with some work. a muon type neutrino interacts with a stationary electron, producing a muon and electron type neutrino. I have calculated the CM energy but now need to calculate gamma, the lorentz boost. γ=(Eν/2me)^1/2 How do i show this? the info i have is that...

So I was studying some physics, and I keep encountering how many things depend on the frame of reference. For example, kinetic energy and momentum. My question is if there is an absolute frame of reference? Can we define one? I remember reading somewhere that the absolute reference...

Hi, I have a simple question in my mind, I could not find the answer anywhere so I came here. Here is my question, Assume a source of light and observer are five light seconds apart, and are travling parllel to each other at a constant speed of say 200 meters per second. Now if the source of...

Please teach me about this: Are there any change in energy and momentum of photon in different frame?Are there any analogies with Doppler effect? Thank you very much in advance.

Hi all, Trying to design a simple gate for the side of our house and in order to select the size of the square tube for the frame, I need to calculate the forces in the members of the frame. I have tried the method of sections and joints, however both do not seem to work. My next...

Hello :) An object is placed far away from all the bodies that can exert force on it. A frame of reference is constructed by taking the origin and axes fixed in this object. Will the frame be necessarily inertial? Hmm According to me, it should be an Inertial frame as No force acting on it...

Objects smaller than black holes, by mass can still drag space along with their rotation. I picture this like a plate of Spaghetti there the pasta is radiating out from the center of the plate. But let's say its rubbery spaghetti and can stratch. And its attached at one end to the outer egde of...

Hi there, I've got an assignment due today and as usual have left finishing it off until the last minute. I've completed most of it but I thought I'd try and get an opinion on something. Homework Statement Basically our teacher has asked us for a very simple steel frame (beam, column...

me and my friend were arguing (like always) about inertial frame ? to sum up i m just asking a straightforward question ? let say (for simplicity) there is just Earth and an other object in whole universe. a point whose distance from Earth is x. and dx/dt = 0. now is that point (which...

Hi: I’m a new member to this forum. I’m looking at the behavior of frame dragging around a rotating black hole. It seems to me that frame dragging should be zero about a rotating black hole’s axis of rotation, but should be at a maximum at the equator (i.e. 90 degrees from its axis of...

Homework Statement Located here:http://imgur.com/qP9fd.png" The Attempt at a Solution I don't know how to do this problem. First of all how do I approach it? Should I do a free-body diagram? Should it be done at position 1? How do I account for the different frame of reference...

Homework Statement A student is in a rotating chair with a pendulum hanging down in the middle of the rotation. . I need to calculate the difference in tension when the bob is hanging vertically and when the chair is rotating. The length of the bob and string is 65.3 cm. The radius of the...

Hi, I'm stuck with a question concerning electric fields : Can an electrostatic potential drop exist in (what I would call) a 0 dimensional system ? Let's imagine we are in a region of space where there is nothing but a uniform magnetic field. So the problem is anisotropic but does not...

Major difference of Inertial and non-inertial frame of reference ?? What is the major difference or differences of Inertial and non-Inertial frame of reference?? Is it only: Inertial - Constant velocity, obeys the law of inertia Non-inertial - Acceleration, disobeys the law of inertia

Hi all, I massively appreciate any help in advance. I have an exam coming up and am completely stumped on a question regarding reinforced concrete design. The teacher has told us the question is going to be similar to the example he has given us but hasn't gone through it with us. It is a...

Earth is clearly not an inertial frame, its in orbit and not following a single direction of movement. Why then do we treat it as one? Are there any slight differences in the laws of motion in a true inertial frame in contrast with those on earth?

Homework Statement Consider a bead sliding without friction on a circular hoop of wire rotating at constant \Omega, where \phi is the angle between the bottom of the hoop and the bead. Find the equation of motion of the bead. \hat{\Omega}=\hat{z} Homework Equations...

I really don't quite understand the result of time dilation. Let's say that we have two identical twins A and B. Twin A is at rest and twin B is on a high speed rocket ship. Let's say that 10 years has passed in frame A. According to relativity, the twin in frame B is supposed to measure less...

Well, in principle, this problem seems very easy but I don't know the exact explanation.Here we go. We have a truck and a pack in its back.The bed of the truck is frictionless and the pack is stopped by a small piece of wood of something like that. The size of the pack is whatever(for...

i am facing problem in attempting the peoblem attached below if i work in the non inertial frame (the rotating) shouldn't the acceleration of m_a after the catch is removed be simply =\omega2ra thanks in advance

Homework Statement A key concept about the center-of-mass frame is that A. the total momentum in the center of mass frame is always zero. B. both the initial and final momentum vectors form pairs of equal magnitude and opposite direction C. this frame always moves at the same velocity...

Hello, everyone I am studying Srednicki's "Quantum Field Theory", section 4 "The spin-statistics Theorem". Does anyone know how to show that "The time ordering of two spacetime points x and x' is frame independent if their separation is timelike."(P32), explicitly? And "Two spacetime points...

I'm trying to show that the Frenet frame structural equation for a curve in R_3 can be written in the following form for a vector W(s): T'(s) = W(s) x T(s) N'(s) = W(s) x N(s) B'(s) = W(s) x B(s) The problem I'm having here is that I define first that T(s) should be the unit tangent at...

Hi I am new to the design game as it where and I have scoured books and the internet looking for calcs, examples, help with a design I am putting together which involves raising and lowering a heavy object using a lead screw. I know its not strictly CNC stuff but I believe someone may be able...

Blandford & Thorne, Applications of Classical Physics: Taylor & Wheeler, Spacetime Physics: These definitions seem to be based on the notion of a "physical" or "practical" infinitesimal: a quantity too small to be detected. But how can we measure the accuracy of an imaginary detector...

Okay, weird question. Sorry if this is really stupid but it's been bugging at me for days now. First, let me lay out my current assumptions/understanding of what's going on. The current theory seems to be (to an amateur like myself) that there is no fixed space-time. That to talk about...

what is inertial frame of reference. lets say motion is in 2d universe (x,t) consider three points f,a and b the distance of a and from f be x and y respectively. for what equation (s) of motion f would be inertial frame of reference for a ? what does it mean that Newton's law hold...

I see a lot of places, "The speed of light is the same in all inertial reference frames." But is it the same in non-inertial reference frames too? For example, your reference frame/observer is accelerating according to someone else holding a flash light, at the moment they meet, the other...

Homework Statement http://img571.imageshack.us/img571/2026/framekq.jpg I need some help with finding the forces associated with this structure. I drew it badly from how a friend described it. A point load would be placed on it so, a weight W would be at the centre + the weight of the...

I have read many arguments concerning the issue of the famed “Twin Clock Paradox”. Very many arguments go through considerably complex explanations so as to defend Special Relativity or dispute it. But the explanation is actually much simpler. In every proposed twins paradox, there is a Frame...

I know that in Newtonian mechanics an inertial frame of reference moves relative to absolute space. But why does Newtonian mechanics include the contention that two inertial reference frames move relative to each other? It seems that if you have an absolute reference frame then there is no...

You are on an airplane traveling due east at 100 m/s with respect to the air. The air is moving with a speed 35 m/s with respect to the ground at an angle of 30° west of due north. What is the speed of the plane with respect to the ground? __________ So here's what I am doing: Drew the...

Hi In my textbook they were doing a derivation of the acceleration of a projectile flying on Earth. Although they used the center of the Earth as the frame of reference, they ended up with the linear combination of 3 quantities for the acceleration of the projectile, one of which they said...

Hi everyone... i have to design the frame of a moon buggy, which is a manually powered vehichle for 2... it is somewhat similar to the frame of FSAE cars... but the problem is... i don't know from where to start... i have ideas... but to design a proper frame... i need some study material...

Homework Statement I am trying to find the total energy of a twobody system (two planets orbiting each other) in the center of mass frame. And I was so wondering how to think about this problem.. I know that the kinetic energy in the center of mass is just the sum of the kinetic energies...

The Earth rotating on its equitorial axis spinning on its poles. The Sun has its orbit on the ecliptic 23 degrees away from the spin if the Earth. Is the time frame different at the Earth on the Ecliptic plane rather than the Equitorial?

For a long time, I have wondered if space has a preferred reference frame. As one looks at the cosmic microwave background radiation, ask your self what would it look like if I accelerated myself in one direction. You would expect a bluer shift in one direction and redder shift in the other...

Hello, I have a question about a spinning symmetric top: When the equations of motion are solved, they are solved in two frames--the space frame and the body frame. I understand the space frame, but in the body frame you are looking at the top from a frame that is rotating with it, right? So...

Hi All, Suppose a photon is approaching the origin of set of three cartesian axes, along the negative part of the z axis. If we put a slit, geometrically defined as: 1a) half plane z = 0 and x >= epsilon 2a) half plane z = 0 and x <= -1 * epsilon Note that the slit width is 2 *...

Homework Statement A simple pendulum that consists of a mass m and a massless cord of length L is hanged on the ceiling of an elevator, which is intially at rest. The pendulum is performing a simple harmonic motion. The energy of the mass (Kinetic energy + potential energy with respect to...

http://img14.imageshack.us/img14/1399/blahblahr.jpg Uploaded with ImageShack.us Homework Statement These stairs are rotating as a whole while a dog is climbing on them with a velocity v relative to them, as shown. The angle that these stairs make is 60 degrees, and the radius is R. 1...

Hello, I've always wondered about the "relativity" of the De Broglie wavelength. The wavelength depends on the momentum of the specific thing we are observing, thus on different frames of reference(F.O.R from now on :P) we might get different answers. I have been looking through the web to...

I. Overview Another SA asked me to elaborate on a remark I made to the effect that frequency shift phenomena always (even in Minkowski vacuum) involve at least the following ingredients: two (proper time parameterized) timelike curves C, C' an event A on C ("emission event") an...

I'm having some trouble reconciling the following facts: 1) that kinetic energy depends on v _squared_, 2) at the same time energy is conserved in all reference frames, and 3) reference frames transform linearly in v in classical mechanics (galileo transform). I've basically been able to boil...

Has anyone used the Simple-PCI program to couple with the Meteor-II Digitcal PCI card for imaging from a commercial microscope like the Nikon Eclipse? Our version of the Simple-PCI does not recognise the frame grabber at all. Any help is appreciated. Ising