All Questions
Tagged with classical-mechanics reference-frames
203
questions
1
vote
1
answer
79
views
Non-inertial frames in quantum mechanics
In classical physics, non-inertial frames necessitate adjustments to Newton's laws due to acceleration and rotation, yet in general relativity, Einstein successfully incorporates such frames. Why does ...
- 15
1
vote
1
answer
68
views
The square of the center of mass [closed]
In the book Classical Mechanics by Goldstein, there is an exercise related to the square of the position of the center of mass of a free particle. I must prove that
$$M^2R^2 = M\sum_i m_ir_i^2 - \...
0
votes
2
answers
90
views
Does relative motion allow for speeds $>c$?
If motion is relative, (so if X was stationary and Y was moving at v m/s, we could think of this as Y being stationary and X moving at -v m/s), could we not create a scenario in which a stationary ...
0
votes
2
answers
49
views
Properties of the Center of Mass
My students are currently going through the rigid rotor and hydrogen atom unit in their quantum physical chemistry course and I found myself at a loss on how to justify what seems a natural way to ...
- 3,202
0
votes
2
answers
74
views
Energy in different coordinates in central force motion
With reference to central force, we see that K.E has 2 terms in 2D cartesian cordinate but just 1 term in polar coordinates and potential energy has 1 term in cartesian but 2 terms in polar.
Basically ...
- 367
0
votes
1
answer
36
views
Doppler shift phenomenon for non-inertia frames
The Doppler shift phenomenon is well understood when the source and observer are in relative constant motion. However, I'm curious to know how the Doppler shift phenomenon is modified when they (i.e., ...
- 342
0
votes
0
answers
19
views
2d elastic scattering with an impact parameter
Hello guys I have homework that has tasked me with connecting the effect of the scattering parameter to the energy transfer in a 2d elastic collision of two arbitrary spheres with one of them standing ...
- 1
1
vote
2
answers
78
views
Why isn't there such a thing as "internal momentum"?
The three most well-known conserved quantities in classical physics are energy, momentum, and angular momentum.
Suppose we have a system with no external forces acting on it. We can talk about the ...
- 8,640
1
vote
1
answer
49
views
How do physicists determine where to place the world or inertial frame when describing the equation of motion of an object?
For example, I have a pendulum as shown in the diagram above. I would like to write down its equation of motion. To do this, I must define a world frame (or inertial frame, or origin).
But this is ...
- 320
2
votes
1
answer
89
views
Time derivative of a "general" vector $\vec A$ in an accelerating frame: what about e.g. velocity $\vec v$?
According to Morin "Classical Mechanics" (Section 10.1, page 459), the derivative of a general vector $\vec A$ in an accelerating frame may be given as
$$\frac{d\vec A}{dt}=\frac{\delta \vec ...
- 23
5
votes
5
answers
2k
views
Why is the centre of mass useful in a discrete particle system?
How does the concept of center of mass apply to discrete particle systems with varying masses and motions, especially when dealing with a large number of particles?
Considering the challenge of ...
- 91
1
vote
1
answer
60
views
Question about distribution of mass
I recently began taking my first university-level physics course after having studied quite a bit of pure mathematics. While I think that my math background has helped me grasp some concepts a bit ...
- 11
1
vote
4
answers
219
views
Reference frame doubts about isotropy
Landau & Lifshitz on p.5 in their "Mechanics" book states the following:
...a frame of reference can always be chosen in which space is
homogeneous and isotropic and time is homogeneous....
1
vote
0
answers
36
views
How do 4-vectors change under an "accelerated" Lorentz transformation?
I assume that an observer moving with velocity $\mathbf{v} = v\mathbf{n} = \mathbf{v}(t)$ (with respect to another observer) has coordinates
where $x^{\mu}$ are the coordinates for the observer who ...
- 391
0
votes
0
answers
14
views
Reading on weighing scales at the equator of a moon in a tidally locked two-body system
I'm trying a made-up extension of this problem. Consider the planet Mars and its moon Deimos, which can be approximated as meeting the following simplifying conditions:
Both objects are perfect ...
- 208