Frame Definition and 1000 Threads

Hello, I wish to know what is the relationship between a frame of reference and time. Specifically,without a frame of reference, what would be a hypothetical state of time. Professor Witten predicts that an ultimate physical theory will dissolve space-time as we know it. I would like to discuss...

So if i take a picture (for example) 30 fps camera. So my question is that: is the time in the picture 1 s \ 30 fps or is it just 0? (May be very stupid question)

If I am sitting, not moving, my velocity can be zero along with my acceleration but in truth the Earth is moving along with the solar system and so on but i want to know theoretically if a massless object in space can have zero velocity and zero acceleration, in essence what i am askimg is can...

What kind of frame of reference do I have to choose when I'm studiyng lens and mirrors? As far as I know you consider positive the direction where the rays are real and negative the one where the rays are virtual, is that always true? Why can't we study a problem of optics choosing a frame of...

I don`t understand how synchronization of clocks can be made in an accelerating frame. let`s put a source of light at the center of an accelerating rocket. From it, many pairs of pulses are emitted one at a time in two opposite directions. Because the source is located at an equidistant from two...

Homework Statement We are given this frame and asked to find the forces at C, D, E and F. Distance from D to E is 16 feet. Distance from C to D is 8 feet; distance from E to F is also 8 feet. Distance from A to D is 6 feet; distance from D to G also 6 feet.[/B]Homework EquationsThe Attempt...

... in order that one's clocks will lose: (a) 1 second per day as observed from S? (b) 1 minute per day as observed from S? I was referencing this:( http://hyperphysics.phy-astr.gsu.edu/hbase/relativ/tdil.html#c2 ) hyperphysics page but I still can't seem to understand what I need to do to...

Whenever we define torque from a frame of reference, is it necessary for the frame to be inertial? Please explain because I am unclear on this.

Homework Statement I have a doubt about the way to calculate the centrifugal acceleration for a point P that rotates with angular velocity ##w_1## wtr a inertial frame on a platform that rotates with angular velocity ##w## (##w_1>w)##. I want to find the centrifugal acceleration in the...

1. The problem: If the Sun blows up at some instant and four minutes later we on Earth sit down to eat lunch, these two events are separated by a spacelike interval. The explosion of the sun cannot have influenced us at the time we sat down because it takes 8 minutes for light to reach us from...

Homework Statement A platform rotates with ##\omega=10## rad/s around ##z##-axes. A ball is connected, with a yarn to ##z##. Its distance to the axes is 15 cm and it rotates with ##\omega=10## rad/s. There isn't friction between platform and ball. Suddenly, the angular velocity of the...

Hello, My understanding is that a a frame of reference is a theoretical framework that is used to describe the motion of an object allowing for measurements of position, distance and time. A frame of reference always implicitly includes a coordinate system (cartesian, spherical, cylindrical...

Homework Statement When the piston CD is lowered, ACB and CBE are horizontal, and they ask for the force in piston CD. Homework EquationsThe Attempt at a Solution So first we look at the entire frame ACDBE, and we sum moments at A: -(14)(2500) + 24E(suby) = 0; E(suby) = 1458 Then A(suby) is...

Hi all, I've been self-studying a first year uni introductory mechanics course, and I'm confused with the derivations involved in calculating the final state of an elastic collision in one dimension, given the initial state. So basically we have masses of m_1, m_2 with initial velocities v_1i...

Homework Statement Suppose that in a fixed-target proton-proton collision, the two protons are scattered with equal energies at equal angles θ/2 to the beam. Show that in the CM frame, this implies they are scattered at right angles to the direction of the beam. Calculate the energy and...

Is the inertial frame of reference the same thing as space time?

I'm in college working towards a degree in Mechanical Engineering, so far I've only made it through physics 1 and calculus 2, but I've been building race cars and pulling trucks and tractors since i could hold a wrench. I work for a guy that builds super modified four wheel drive pulling truck...

Homework Statement A particle of mass m ha speed 0.546c relative to inertial frame S. The particle collides with an identical particle at rest in the inertial frame S. Relative to S and in terms of c, what is the speed of S' in which the total momentum of these particles is 0. Homework...

I'm currently doing a student project at uni and I'm trying to design magnetorquers for cubesats.Before I make the prototype I need a simulation of what will happen.The problem is that for my calculations,I need to change the frame of reference of the geomagnetic field.So basically I need to go...

When rotation exists, so does the radial acceleration. It can be defined as ar=-ω2xr So there is a kind of acceleration with rotation all the time. Thus, we have to use non-inertial reference frame all the time. Could a rotational movement be analysed in an inertial ref. frame?

Homework Statement What is the Lorentz-transformation that one would use to go from the lab frame to the Breit Frame? [/B]

my book says " the total momentum is zero in the centre of mass reference frame.This should not surprise you" but ITS NOT INTUITIVE FOR ME. I am considering a completely elastic collision. 1. I know the v_cm is const because there are no ext forces on the system of the two masses undergoing 1D...

we use perfect fluid which is characterized by a energy density and isotropic pressure for general forms of matter. When guessing the values of energy momentum tensor indices we can use the physical insight that they are the flux of four momentum in a constant surface of spacetime. The...

So, a friend asked me this question in school and I've come up with an answer, I'm just not sure that it is right. Say you have a charged particle moving perpendicular to a magnetic field. There will be a force acting on it given by F=qvB. Now suppose your'e moving along at the same velocity as...

The reason we can choose a frame of reference arbitrarily is that a physical system is not dependent on an absolute position, orientation or time. According to Noether's Theorem, the invariance of a system under a change of position is equivalent to the momentum conservation law. In the same...

Hello, in general relativity we introduce local inertial frames to be such frames where the laws of special relativity holds. Let ξα the coordinates in the local inertial frame, so we get ds²=ηαβdξαdξβ. If we switch the frame of reference to coordinates xμ : ξα=ξα(x0,x1,x2,x3) and with...

Homework Statement Recently, I have been wondering whether forces are independent of reference frames(inertial and non inertial). From Newton's law we know that the second law is valid only for inertial frames. But what about the non inertial frames. Let ∑F be the net force on an object in an...

Hi, new here, with bits & pieces of basic college physics rattling around in my brain from years ago, so explain things at that level, please. I am building a cold frame in order to try growing food through the winter in NJ, USA. It will get below freezing here at night but not every day. I...

Homework Statement A particle with mass M at rest decays into two particles with masses ma=0.15M and mb=0.65M . i) Discuss the relative directions and magnitudes of the momenta of these two particles in the centre of mass reference frame. Homework EquationsThe Attempt at a Solution What's the...

Is it meaningful to measure the speed of an object in a rotating frame, and if so how do you do it in the following case? Consider a rim of circumference 100 rotating at 0.8c, both measurements with respect to the inertial lab frame. An object is at a point on the rim with a standard clock...

In an inertial frame of reference let numerous standard rockets that load synchronized standard clocks place on all the space lattice. Simultaneously the rockets start to move with same intrinsic acceleration to the same direction. In other words there exists a common instantaneous inertial...

Homework Statement Hi all. What concerns me here is that it's worth 10 marks, but the solution I've tried only takes 2 steps. Am I missing some relation between the frame support and the pulley altering the components of the tension, or is the solution really just a basic trig conversion...

Hello, I have the following problem: A system in the lab frame is described by a time dependent rotating potential ##V(\vec{r},t)##. So ##H_{lab}=\frac{\boldsymbol{p}^{2}}{2m} + V(\vec{r},t)##. My book says that the Hamiltonian in the rotating frame is given by...

This is the question: http://i.imgur.com/Ex2Yx4l.png I have calculated all the angles in the frame, and have drawn line of forces so that the reaction force at x, reaction force at y, and the 10KN meet up. From then I am stuck, and don't know how to find the angle theta...

I'm 11 and I'm trying understand what Special Relativity is about. How many different inertial frames of reference do we have and what are they?? I know what it means.

Homework Statement Homework Equations Xcm = (x1m1+x2m2) / (m1+m2) The Attempt at a Solution ok so I'm having trouble understanding what's happening in the question... when the penguin moves, is the sled also moving? If it's friction less ice then if the penguins moves L, the sled will...

If light travels in a straight line , why can't we use it as absolute frame of reference? This thought experiment is done in the absence of external forces and gravity. One person standing inside a box ,sends a photon parallel to the bottom of the box from one end to another end , whether...

I was thinking about entanglement today and found myself struggling to envision entanglement and relativity working together. If I send entangled electrons out in opposite directions, their states are not determined until one of them is observed. I know that. What if one of them passes...

Homework Statement It is not a homework question.I am trying to understand the concept in the attached diagram but I stuck.Hope someone can help Homework EquationsThe Attempt at a Solution Please see the lower part of the note,stating that Δt' = Δt/γ.However,imagine you are in the moving frame...

Homework Statement The height of motion picture film's frame is 35 cm.If 24 frame go by 1 sec calculate the total number of frames required to show ia 2h long motion picture. Homework Equations simple Equation which I don't need to write here I guess The Attempt at a Solution The Height of...

Hi, I have a reference device that outputs euler angles, which are angles that relate the sensor body frame to the north east down frame. These angles are called pitch roll and yaw. The sensor is an accelerometer. I know how to get the rotation matrix that will put accelerations from the...

Hello PF. There are two lightning flashes , and two stationary observers. Observer 1 who is equidistant from the flashes, sees them as simultaneous Observer 2 stands one step to the side of observer 1, and is not equidistant. He sees the flashes as separate, the light having unequal distances...

Hello all, was it ever a point of discussion in cosmology, quantum-theory, mechanics, etc. that there is a fundamental difference in describing a physical process in a 2n-grade (4th, 6th, 8th-grade) frame of reference in comparison to a 2n-1-grade (3rd, 5th, 7th-grade) frame ? Thanks in...

I'm just beginning physics and teaching myself classical physics from an intro physics textbook and in the 2nd chapter it described reference frames. This got me thinking. My reference frame is the earth, as that is what I use to describe position, displacement, ect. But what is the reference...

Hi, This might sound very basic and but i am just starting to learn physics. I an lecture by prof. walter lewin, he descibes the hunter and monkey scenario. The monkey jumps from the tree as soon as the hunter aims and shoot his gun. the bullet hits the monkey anyway. In calculating the time it...

Hello, I've been thinking about inertial and non inertial reference frames. A common example is non rotating reference frame vs a rotating reference frame. As illustration, I have attached two images below. The left is the inertial frame and the right is the non inertial frame. Both...

How does one derive the general form of the Riemann tensor components when it is defined with respect to the Levi-Civita connection? I assumed it was just a "plug-in and play" situation, however I end up with extra terms that don't agree with the form I've looked up in a book. In a general...

Homework Statement An electron moves to the right with a speed of 0.90c in the laboratory frame. A proton moves to the left with a speed of 0.77c relative to the electron. Using the Lorentz coordinate transformations, find the speed of the proton in the laboratory frame Homework Equations $$...

Homework Statement A quadratic frame which has an edge of ##a=10 cm##, was put inside a magnetic field ##B=0.01T##. The frame's opposite vertices were being pulled with a uniform speed ##v=1mm/s## until the frame became flat. Find the charge that passed through the frame. The plane of the frame...

So, I've been working through "Exploring Black Holes: Introduction to General Relativity" by Taylor and Wheeler, and I'm somewhat puzzled by a term in the "Rain Frame." The "Rain Frame" is meant to be a frame of reference of an object initially released from rest at infinity as it free-falls...