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Question 1

-2votes

1answer

119views

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 ...

imbAF

2,048

asked14 hours ago

Question 2

4votes

6answers

320views

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 ...

Santhosh Kumaran

43

askedNov 22 at 11:27

Question 3

-3votes

1answer

95views

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....

Simon Fresnay

13

askedNov 22 at 10:31

Question 4

6votes

2answers

1kviews

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 ...

Lem n

63

askedNov 19 at 20:14

Question 5

-1votes

3answers

162views

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 ...

Mintaka

121

askedNov 19 at 7:50

Question 6

3votes

1answer

166views

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 ...

tparker

52.3k

askedNov 16 at 21:01

Question 7

0votes

1answer

132views

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 ...

Owlywolf

507

askedNov 12 at 15:47

Question 8

1vote

1answer

89views

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 ...

ИванКарамазов

111

askedNov 5 at 20:23

Question 9

0votes

1answer

112views

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 ...

moshtaba

1,685

askedNov 5 at 2:38

Question 10

2votes

2answers

88views

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 + ...

jeffreygorwinkle

187

askedNov 4 at 17:23

Question 11

7votes

5answers

2kviews

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 ...

Adeeth

73

askedNov 3 at 13:52

Question 12

0votes

0answers

66views

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 ...

moshtaba

1,685

askedNov 1 at 10:15

Question 13

4votes

4answers

491views

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{...

cosimoNigro

321

askedOct 29 at 16:48

Question 14

0votes

2answers

73views

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 ...

Owlywolf

507

askedOct 27 at 13:51

Question 15

0votes

1answer

59views

Principal axis of circular disc with removed circular portion [closed]

From a circular disc, a circular portion of radius R/2 has been removed....it is asked if the axis YY' is principal axis or not...so my first intuition was since the axis is not symmetric this should ...

Riya

1

askedOct 24 at 8:13

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Stack Exchange Network

Questions tagged [reference-frames]

How does the concept of "coordinates" makes sense when considering large scales of the universe?

Proof and meaning of $\vec{v} = \vec{\omega}\times\vec{r}$

Has someone ever obtained a relative trajectory being exactly the Coriolis formula without a background centripetal force (as gravity)?

Do blueshifted and redshifted light sources have differing energies?

What force(s) is rotation made of? [duplicate]

Is the age of the universe significantly different as viewed from the Earth's frame of reference than as viewed from the CMB frame?

Clock on a moving rocket

Doubt about Lagrangian transformation between reference frames (Susskind, Classical Mechanics, The Theoretical Minimum, pag.117)

Equivalence principle and principle of relativity

How is using the principal axis frame in the Lagrangian allowed?

Will a Coin rotate always about its diameter/com when Tossed?

Is modified mass of special relativity inertial or gravitational? [duplicate]

On the meaning of the radial coordinate in the simplification of the Two-Body Problem. Inertial or non-inertial reference frame?

Rotation of wind in low and high pressure zones

Principal axis of circular disc with removed circular portion [closed]

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