Questions tagged [reference-frames]
A reference frame is a particular coordinate system chosen to represent physical entities. The notion is most often used in special and general relativity to denote particular coordinates chosen on the spacetime manifold.
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Application of Reichenbach synchronisation
Suppose I adopt the Reichenbach synchronisation process so that light heading radially away from me- according to my clocks- travels with infinite speed, while light heading directly towards me ...
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How does the concept of "coordinates" makes sense when considering large scales of the universe?
I will describe two instances, that led me to ask the question of relevancy or meaningfulness of coordinates when we are not local in our observation of the universe, but rather we consider a large ...
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Proof and meaning of $\vec{v} = \vec{\omega}\times\vec{r}$
Elementary question but I'm slightly confused about the statement $$\vec{v} = \vec{\omega}\times\vec{r}.$$ I know that $\vec{\omega}$ is simply the time derivative of $\theta$, which, to make things ...
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Has someone ever obtained a relative trajectory being exactly the Coriolis formula without a background centripetal force (as gravity)?
In geophysics and many other cases, the Coriolis formula is clearly linked to a background centripetal force.
Read Anders Persson (UK MetOffice, EU ECMWF, Sweden SMHI, Uppsala) https://scholar.google....
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Do blueshifted and redshifted light sources have differing energies?
The thought experiment:
Two spaceships are passing each other some distance from a star. Both ships are at relativistic speed, one toward and one away from the star. Should the total energy observed ...
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What force(s) is rotation made of? [duplicate]
Can the rotation of an object be viewed as the result of two perpendicular forces ('push' and 'pull') that have combined? When I spin a wheel there is a 'push force' at a right angle to the wheel's ...
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Is the age of the universe significantly different as viewed from the Earth's frame of reference than as viewed from the CMB frame?
The standard value given for the age of the universe is 13.79 billion years. But of course, that age depends on the frame of reference; that figure is given from the perspective of the comoving FLRW ...
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Clock on a moving rocket
Let's say that there is a clock mounted outside a rocket that is moving at a constant velocity upwards as measured by an adjacent observer looking at the clock from a stationary platform. The clock's ...
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Doubt about Lagrangian transformation between reference frames (Susskind, Classical Mechanics, The Theoretical Minimum, pag.117)
I'm working through Susskind's Classical Mechanics book and I reached the point where he explains how to transform the action (and Lagrangian) when changing reference frames. However, I believe there ...
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Equivalence principle and principle of relativity
If equivalence principle was not true could we have almost inertial reference frames near the earth? Specially, is it was possible for a person in a train to know that if it is standing still or it is ...
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How is using the principal axis frame in the Lagrangian allowed?
The kinetic energy of a fixed, rotating rigid body is
$$
T =\frac{1}{2}\mathbf{\omega}\mathbf{I}\mathbf{\omega}=\frac{1}{2}I_{xx}\omega_x^2 +\frac{1}{2}I_{yy}\omega_y^2 + \frac{1}{2}I_{zz}\omega_z^2 + ...
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Will a Coin rotate always about its diameter/com when Tossed?
When a coin is tossed in the air by applying an impulse at some distance from the Centre of Mass (centre of ring), it will start rotating and move up vertically as well.
Can we say that the coin will ...
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Is modified mass of special relativity inertial or gravitational? [duplicate]
Is modified mass of special relativity
$$m= \frac{m_0}{\sqrt{1-(v/c)^2}}$$
inertial mass or gravitational mass?
I hope $m$ be both of them: we know accelerating massive particles to speed of light is ...
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On the meaning of the radial coordinate in the simplification of the Two-Body Problem. Inertial or non-inertial reference frame?
When presented with the two-body problems, we usually start from Newton's 2nd equations for the two bodies:
$$
\begin{split}
m_1 \mathbf{\ddot{r}}_1 &= f(r) \mathbf{\hat{r}}, \\
m_2 \mathbf{\ddot{...
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Rotation of wind in low and high pressure zones
Why do winds rotate counterclockwise around low-pressure systems and clockwise around high-pressure systems in the Northern Hemisphere?
If this rotation of wind is because of the Coriolis effect ...
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