What is Reference frames: Definition and 227 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.
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...
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...
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...
Homework Statement
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...
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...
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...
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...
My textbook basically defines an inertial reference frame as follows: If you have an object O that has no forces acting on it, and there is a reference frame R where the acceleration of O with respect to R is zero, then R is a inertial reference frame.
This to me seems circular. How does one...
Hi - I've just started having lectures on special relativity at uni. We were talking about inertial reference frames and how these can be characterised by the facts that:
1) They move relative to one another with constant velocity, and
2) Newton's laws operate in inertial reference frames...
under which conditions we could say that the same experiment is performed in different inertial reference frames. I have formulated for myself the following answer:
We say that observers from two inertial reference frames perform the same experiment if the physical quantities they measure are...
Hi,
Please help me, I can't make head or tail of the concept of an inertial reference frame. What is an inertial reference frame? In what fundamental way does it differ from a noninertial reference frame if all motion is relative? Thanks for your help.
Molu
Is the comparison of the kinetic energy of a satellite in orbit around the Earth to that of a truck traveling down a road realistic? Are they in the same reference frame?
This is a highly theoretical question... so beware!
The Work Energy(WE) equation in Mechanics says that the net total work done on an object due to various conservative and non-conservative forces equals the change in kinetic energy of the body. This above theorem is usually derived simply from...
After a dispute on the nature of kinetic energy on a previous topic,
a new question has arised.
If kinetic energy is different for each reference frame,
then what happens with mass, considering the mass-energy
equation?
why is it that when two events occur simultaneosuly at separated points on the x-axis of reference fram S, the observer moving in the positive X direction sees the event withe largest x coordinate first
shouldnt it be the smallest?
gre problem: special relativity, two events in two reference frames
34. In an inertial reference frame S, two events occur on the x-axis separated in time by \Delta t and in space by \Delta x. in another inertial reference frame S', moving in the x-directon relative to S, the two events could...
1) Which object provides an inertial frame of reference?
a. the tip of the moving second hand of a clock
b. a rock thrown vertically upward
c. a pendulum swinging with no air resistance
d. a skydiver falling at terminal velocity
At first I thought c might be correct, but now I am...
hi folks!
I have a question which had been haunting me for quite some time...
can an observer sitting in a accelerating reference frame deduce that he is accelerating without establishing any contact with the outside world( i am alluding to outside the frame ambience)?
Is it possible to define one's identity (i.e. answer the question "Who are you?") without resorting to some sort of reference frame (e.g. "I am the son of so and so"), and if so, how?
And for that matter, is there anything at all out there, which can be defined without a raference frame? I...
I can make a local inertial reference frame in a gravitational field by creating a frame that is small but close to the source of curvature of space-time.
Alternatively I can make a local inertial reference frame by creating a frame that is large but a long distance from the source of curvature...
Suppose 2 inertial frames with relative relativistic velocities.
To discuss phenomena in other frame, we need to use Lorentz Transform for length and time. I got question: do we have to also use LT to talk about permittivity and permeability of other IRF? This seems strange. Permittivity has...
1. Let clock A and clock B be of identical construction, and let them both not be subjected to any force. Let them be at rest with respect to each other. Thus, the relative velocity v is equal to zero.
Therefore, using Newtonian mechanics or SR, the clocks tick at the same rate. For the...