All Questions
Tagged with classical-mechanics reference-frames
30
questions
6
votes
6
answers
690
views
Validity of rotational Newton's second law in a changing instantaneously inertial frame
A standard textbook question is to ask about some rigid body (say, a 2D disk) rolling down an incline without slipping (cf. John Taylor's Classical Mechanics, Problem 3.35).
The standard approach is ...
- 1,095
6
votes
1
answer
603
views
Energy usage in different reference frames
Imagine a moving object at constant speed (like a car). This object is, then, accelerated for a brief moment. In different reference frames (at rest and moving along with the object), the variation of ...
- 133
4
votes
1
answer
392
views
Confusion about imposing constraint in the action
I'm totally confused by one thing. I know that I probably shouldn't be confused about that, but at the moment I don't quite know what fails in the following:
Suppose we have a particle of unit mass ...
- 909
3
votes
4
answers
675
views
Understanding the definition of tangent basis
This question could sound silly but I though a lot about it and I'm not new to physics.
Let's say I have a plane on which I use polar coordinates, it means a point $P$ can be indicated by its ...
- 1,904
3
votes
1
answer
1k
views
Why is total kinetic energy always equal to the sum of rotational and translational kinetic energies?
My derivation is as follows.
The total KE, $T_r$ for a rigid object purely rotating about an axis with angular velocity $\bf{ω}$ and with the $i$th particle rotating with velocity $ \textbf{v}_{(rot)...
user86425
2
votes
3
answers
2k
views
Lagrange Equations for Non-Inertial Frame of Reference
I am trying to expand my limited knowledge of Lagrange's equations for evaluating motion. Regarding the Lagrangian in a rotating coordinate system, the text Mechanics by Symon states "...we use ...
- 9,381
2
votes
1
answer
171
views
Why is this hamiltonian not the energy? [duplicate]
Let a pendulum of length $\ell$ be connected to a rod that rotates with constant angular velocity $\omega$. $\theta$ is the angle of the pendulum wrt $z$ axis ($z$ axis is parallel to the rod).
I ...
- 980
2
votes
2
answers
12k
views
When does not Newton's 3rd law apply?
Is Newton's 3rd law valid in non-inertial frames?
If so, then are there other cases for which Newton's 3rd law is not applicable?
- 17.1k
2
votes
2
answers
589
views
Galilean transformations of velocity
If I perform a Galilean boost $$x' = x - vt \\ t'=t$$ between two frames $S$ and $S'$, observers in each frame would disagree on the velocity of a particle because
$$ \frac{dx'}{dt'} = \frac{dx}{dt} -...
- 3,986
1
vote
2
answers
150
views
Is work done relative according to the theory of special relativity?
I performed a thought experiment.
Consider a body $A$ and another body $B$.
Body $B$ is moving at velocity $v$ in direction $x$ with respect to $A$. This implies that body $A$ is moving at velocity $v$...
user355398
1
vote
2
answers
556
views
What does the Problem 14 from Goldstein's book on classical mechanics chapter-7 (special relativity) really mean?
I am having difficulty in understanding problem number 14 in Goldstein's Classical Mechanics, 3rd edition, chapter 7 on special relativity. Here is the problem ---
A rocket of length $l_0$ in its ...
- 1,088
1
vote
0
answers
3k
views
Meaning of centrifugal term in the mechanical energy of a orbiting planet [duplicate]
For a planet under the effect of gravitational force the mechanical energy can be written as
$$E=\frac{1}{2}\mu {\dot{r}}^2+\frac{L^2}{2\mu r^2}-\gamma \frac{m M}{r^2} \tag{1}$$
Where $\mu$ is the ...
- 2,617
1
vote
2
answers
1k
views
Is acceleration frame dependent or absolute? [closed]
as relative acceleration changes from different point of views so property of things in frame should also change but stationary charge do not radiate E.M waves as seen from accelerating frame i.e. ...
- 177
0
votes
2
answers
189
views
Rotation of non-rigid bodies-centrifugal effect
Suppose that we have a bar of finite length which is rotating about its center of mass at a constant angular velocity in a horizontal plane. Gravity is neglected.
The fact that the bar stretches ...
- 192
0
votes
1
answer
70
views
Doubt in fictitious forces chapter in Morin
The question is this -
I know 2 is what the non-inertial frame measures, but isn't $\frac{d\mathbf{A}}{dt}$ the real thing, the physical thing? And you can write that too in terms of the unit vectors ...
- 430