What is Frame of reference: Definition and 203 Discussions

In physics, a frame of reference (or reference frame) consists of an abstract coordinate system and the set of physical reference points that uniquely fix (locate and orient) the coordinate system and standardize measurements within that frame.
For n dimensions, n + 1 reference points are sufficient to fully define a reference frame. Using rectangular (Cartesian) coordinates, a reference frame may be defined with a reference point at the origin and a reference point at one unit distance along each of the n coordinate axes.
In Einsteinian relativity, reference frames are used to specify the relationship between a moving observer and the phenomenon or phenomena under observation. In this context, the phrase often becomes "observational frame of reference" (or "observational reference frame"), which implies that the observer is at rest in the frame, although not necessarily located at its origin. A relativistic reference frame includes (or implies) the coordinate time, which does not equate across different frames moving relatively to each other. The situation thus differs from Galilean relativity, where all possible coordinate times are essentially equivalent.

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  1. A

    Why does Newtonian mechanics include relative motion between inertial frames?

    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...
  2. D

    De Broglie wavelength and it's dependence of the frame of reference

    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...
  3. W

    Ball dropping and frame of reference

    Consider I am in the train with a ball traveling at normal speed of a train. I drop the ball, it follows a straight path of descent and falls in front of my feet. For an observer on the platform, the ball follows a parabolic path and falls in front of my feet. (Please go to this...
  4. S

    Exploring the Twin Paradox: Searching for the Oldest Frame of Reference

    I was just working on my knowledge of the twin paradox, and had a question that I couldn't find an answer to anywhere: If I understand it correctly the paradox is resolved because the two frames are not symmetrical, one is non-inertial, so that frame has it's clock run slower. So if you carry...
  5. D

    Why is the speed of light independent of a frame of reference?

    I understand the Michelson–Morley experiment and its result; but what I don't know yet is the REASON. Example: A torch in free space is moving at a velocity [v] w.r.t me. Considering the material nature of light, shouldn't the speed of photons emitted from the torch be [v+c] w.r.t ME? According...
  6. Z

    If velocity is subjective to an observers frame of reference?

    If velocity is subjective to an observers frame of reference, then isn't energy (kinetic) also subjective? How can we define energy as objective if it changes depending on your frame of reference?
  7. P

    Frame of reference of any observer

    Let's consider flat 4D Minkowski spacetime. Is it possible to define (local) coordinate system for any observer (its natural reference frame) so that these coordinates posses interpretation of time and spatial position measured by this observer? It can be done in two dimensional Minkowski...
  8. K

    Question on frame of reference

    Why an accelerated frame of reference is non-inertial?
  9. A

    Energy discrepencies depending on frame of reference

    The other day, I was arguing that a car traveling 70mph rear-ending a car traveling 55mph is the same as a car traveling 15mph rear-ending a stationary car. My argument was that, from the frame of reference of the car that was traveling 55mph, the energy of the other car is k(152), where k =...
  10. P

    Light speed in a non Inertial frame of reference

    Does the principle of invariant light speed still hold in a non Inertial frame of reference? Thank you!
  11. F

    Newton 2nd law + frame of reference

    hello forum, i am struggling with the conceptual understanding of this problem: Given two blocks, one on top of the other. There is friction between the two blocks. The upper block is pulled with a force F. Thanks to friction, as long as F is smaller or equal to the static friction...
  12. S

    Earth is a inertial frame of reference

    hi all of u WHAT IS INERTIA? and Earth is a inertial frame of reference or non inertial frame of reference? tell me briefly.
  13. R

    Inertial Frame of Reference & Equilibrium

    Is it safe to say that any object in an inertial reference frame is at a state of equilibrium? If so.. is it safe to say the opposite: that any object in a state of equilibrium is in an inertial reference frame?
  14. G

    What is the Centrifugal Force in Relation to Inertial Frames?

    I am confuse of what is inertial frame of reference. Can someone explain that to me? I need a clear explanation starting from the beginning to the end, and if possible, give me some set of example.
  15. S

    How to derive the ficticious force due to a moving frame of reference?

    Hi guys, I was reading the derivation of ficticious force due to moving frame of reference however i don't understand how they did it.There wasn't detail explanation for slow learners like me so i was wondering does anyone know where i can read up on this or give me some clue where i can start...
  16. R

    Newton's laws and non inertial frame of reference

    Hi all Why do we actually say that Newton's laws do not hold for non inertial frames. can you folks give me an example of how Newton's laws collapse in an non inertial frame(if they do at all)
  17. T

    Collisions and changing frame of reference?

    collisions and "changing frame of reference?" Homework Statement A 6.0Kg trolley moving at 6.0 m/s right overtakes and collies with a 2kg trolley moving 2m/s right in the same direction on the same track. The collision is cushioned by a perfectly elastic bumper attached to one of the trolleys...
  18. T

    How do you tell you are not in inertial frame of reference

    While explaining about inertial and non-inertial frame of reference, people give this example-- http://www.phys.unsw.edu.au/einsteinlight/jw/module1_Inertial.htm if you don't wish to follow the link, here is a simple explanation---> there are two person and a rotating disk. Person A is in...
  19. A

    Spinning Frame of Reference: Inertial or Non-Inertial?

    Homework Statement Is a spinning frame of reference an inertial frame of reference? Homework Equations net torque, net force = ma, equilibrium --> net force = 0, net torque = 0 I've learned that an inertial frame of reference is a frame of reference which is not accelerating. The...
  20. A

    What is an inertial frame of reference?

    Homework Statement What is an inertial frame of reference? Homework Equations -A particle at rest or moving at a constant velocity in an inertial frame of reference implies that the sum of the forces acting on the particle is zero -The tendency of a body to keep moving once it is set in...
  21. DocZaius

    According to Alice's frame of reference

    According to Alice's frame of reference, there is a 1kg object moving through space at 1 m/s along the x coordinate. When x = 0 meters, Alice applies 1 Newton of force to the object in the positive x direction. However, Bob simultaneously applies 1 Newton of force in the opposite direction...
  22. J

    Euler and lagrange frame of reference

    can anybody please clearly explain me the difference between these two frames of reference with few examples. my exames are closing up. please help me.
  23. putongren

    Newton said that all frame of reference are equally valid

    I'm not sure if either Einstein or Newton said that all frame of reference are equally valid. That from my point of view, the laws of physics is the same from your point of view. All frame reference can be put on an equal footing. I was wondering, can one consider the geocentric view that the...
  24. S

    Does the Cosmic Background Radiation Provide an Absolute Frame of Reference?

    According to Einstein, there is no absolute frame of reference; no such thing as 'absolute rest'. But does not the Cosmic Background Radiation provide an absolute frame of reference? An object for which this radiation is totally isotropic is at absolute rest; I gather we move relative to it at...
  25. W

    What would the universe look like from the perspective of a photon observer?

    According to Einstein's relativity theories, each observer is afforded a frame of reference which can be considered central and stationary. What would the universe look like to the frame of reference associated with a photon observer. Would all things be moving past the photon at the velocity...
  26. B

    Does kinetic energy vary by frame of reference?

    Kinetic energy is 1/2mv^2, and velocity varies depending on velocity of the observer, so does kinetic energy also vary depending on the velocity of the observer? for example, someone sitting in a bus who slides a 2 kg brick down the center isle of the bus at 5 m/s could say the has a kinetic...
  27. V

    Time gap between explosions in moving frame of reference

    Came across the following interesting problem : Two explosions take place at the same place in a rest frame with a time separation of 10 s in that frame. A) Find the time between explosions, as measured in a frame moving with a speed 0.9 c with respect to the rest frame according to...
  28. A

    What is an inertial frame of reference ?

    what is an inertial frame of reference ? Simple ?
  29. M

    What Forces Influence the Moon in the Sun's Inertial Frame of Reference?

    What forces affect on the Moon in the Inertial frame of reference which is the Sun? +gravity form the Sun +gravity from the Earth +centrifugal force from the rotationary movement of the Moon round the Earth is this list correct?
  30. M

    Frame of Reference- arrow traveling through a tube

    I was just wondering about the following problem. Suppose that you have an arrow placed in a tube. If the arrow travels at a relativistic speed, does there exist a frame of reference such that the arrow is completely in the tube with extra tube at its ends? Does there exist a frame of...
  31. R

    Why Does an Object Far Away Seem Slow?

    Why does an object far away looks like it's going very slow when it's going really fast? And then the object seems really fast when it's near me. I just started driving and I always try to find an answer but really can't. Thanks :)
  32. S

    Newton's Second Law in NON-inertial frame of reference

    Homework Statement The steel ball is suspended from the accelerating frame by the two cords A and B. The angles (they are on the inside) are both 60 degrees. Determine the acceleration of the frame which will cause the tension in A to be twice that in B. The acceleration is going to the...
  33. K

    Proper frame of reference and the formation of black holes

    Since in our proper frame of reference the fall of material into a black hole would appear to take for an eternity, would it not follow then that all black holes would appear as these instead? Would in fact all black holes appear this way? What if you have a small black hole and then have...
  34. U

    Is Speed Real and Who Has the Correct Frame of Reference in the Universe?

    Our planet is moving through our solar system and our solar system is moving through our galaxy and our galaxy is moving within the local group and are local group is moving through our universe, so how fast are we moving right now, and if i then jump into my spaceship and accelerate am i...
  35. K

    Inertial frame of reference help

    In an inertial frame of reference, a series of experiments is conducted. In each experiment, two or three forces are applied to an object. The magnitudes of these forces are given. No other forces are acting on the object. In which cases may the object possibly remain at rest? The forces...
  36. W

    Why Twins Feel Different Speeds on Opposite Carousels

    Frame of reference... Ok here's a question inspired by relativity and frames of reference. In a funfair, there are two carousels (merry-go-rounds), each 4 meters in diameter and their centers 5 meters apart. They revolve with the same angular velocity, but in opposite directions. We have two...
  37. A

    Frame of Reference vs. Coordinate System

    What is the difference between a frame of refernce and a coordinate system. For example, I know that a rotating frame of reference is non-intertial, but is this also a non-intertial coordinate system? Thanks.
  38. S

    Solving the Paradox of the Frame of Reference

    Here is a question one of my physics teachers mentiones a long time ago. Say you have a 10 ft. car and a 10 ft. barn, so the car will just barely fit. Now say the car saw traveling at an appreciable fraction of the speed of light, and you are traveling next to the car, on the line perendicular...
  39. D

    L's Contradiction Method: Proving EM Laws Independently of Frame of Reference

    Whats the simplest proof that the Electromagnetic laws are independent of frame of reference? .What I know is contradiction method which einstein also used to conclude the postulate of SR. BJ
  40. P

    Velocity and frame of reference question

    Hey I am just lookin for some guidance here of what equations to use for this problem. My teacher gave us likea hint, but the hints are from the book used in the previous course and since i am a transfer stuident, i do not have this book. Anyway the question goes as followed... You are...
  41. andrevdh

    Centrifugal force in rotating frame of reference

    Can someone enlighten me why it is mentioned in the thread https://www.physicsforums.com/showthread.php?p=769852" that when the water is viewed from a rotating frame of reference it experiences an outward centrifugal force. This does not make sense to me.
  42. P

    Frame of reference, Forces, and Angles

    This is more of a concept problem that I'm trying to grasp. Verbatim from the book: "A box is moving with a horizontal velocity, v, relative to an inertial frame of reference so that a medallion of mass, m, inside of the box hangs from the roof of the box with an angle, theta, relative to...
  43. P

    Generalized Lorentz Transformation for an Accelerated Frame of Reference

    This paper by Robert A. Nelson derives an exact, explicit coordinate transformation between an inertial frame of reference and a frame of reference having an arbitrary time-dependent, nongravitational acceleration and an arbitrary time-dependent angular velocity...
  44. K

    What frame of reference is used to measure particle momentum in QM?

    Doing some kinematical calculations we say that particle possesses momentum p. It is definite, so we choose momentum representation to describe the state of particle. However I am curious in what frame of reference we measure particle momentum. We can not assign frame of reference to any...
  45. M

    Kinematics: Defining an Absolute Frame of Reference

    Under "Dynamics", an Inertial frame of Reference can be defined absolutely as one that does not use "pseudo" or inertial forces. Under "Kinematics" how do we define absolutely (any) "Frame of Referaece"?
  46. D

    Time Dilation & Frame of Reference: Who's Time Slows Down?

    Hi all, I know that this isn't a "flaw" in SR. So, I'm not here claiming to have found an amazing flaw in SR. lol. I actually read about this flaw I think, and thus, probably read the solution, however, it was some time ago. So, can anyone enlighten me here please? :) It's related to time...
  47. D

    What Is the Frame of Reference for Measuring Velocity?

    Hi all, I'm pretty young, and thus don't understand any of the relativity theory, well; it's more of a case of "I don't understand WHY..", if you know what I mean :o\ Basically, going to the rule that no mass can equal/breach the speed of light, well, I'm confused here. Not about the most...
  48. E

    Frame of Ref: dx Observed as dt?

    given a frame of reference s In General Relativity in which you meassure an interval of space dx, could we have another frame S`so the observer in that S`see that dx observed in S as a time interval dt?
  49. loseyourname

    Conundrum Regarding the Lack of an Absolute Frame of Reference

    This just popped into my head earlier tonight, for whatever reason. Imagine a photon, a lone photon, that was the only thing in existence. According to relativity theory, am I correct to say that without any other object by which it may be said to be in motion relative to, we cannot say that the...
  50. W

    Frame of reference and Newton's third law

    I can not find the answer for this In a rotating frame of reference, Newton's first and second laws remain valid if we assume that a fictitious force equal to mv^2/r is acting. What effect does this assumption have on the validity of Newton's 3rd law?
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