Questions tagged [classical-mechanics]
Classical mechanics discusses the behaviour of macroscopic bodies under the influence of forces (without necessarily specifying the origin of these forces). If it's possible, USE MORE SPECIFIC TAGS like [newtonian-mechanics], [lagrangian-formalism], and [hamiltonian-formalism].
4,842 questions
0
votes
1answer
26 views
Action principle and Functional derivative in CM
I want to extremize this well known action.
$$S[\phi]=\int \mathcal{L}(\phi(t),\dot{\phi}(t)) dt $$
The result is also well known. It turns out to be E-L equation.
The Action principle states that the ...
0
votes
0answers
20 views
Movement of an object tied to another
Suppose we have two objects $A$ and $B$, where $B$ is tied by a rope to $A$ with the slack pulled out, the initial tangential speed $c'(0)=(0,1)$ is perpendicular to $c(0)$ and $c(0) = (1,0)$, and ...
0
votes
0answers
20 views
Analysis of Motion in a Vertical Circle
I am answering the following question and obtaining a different answer thean given in the text book from which I am working. Can any one see my mistake, or confirm that I am right? By not agreeing ...
0
votes
0answers
19 views
Some questions concerning orbits of objects
I've been playing around with some physics problems and trying to figure out things by myself, mostly just for fun. I would appreciate if someone corrected my thoughts and gave me some feedback. I'm ...
1
vote
1answer
32 views
Relative motion involving acceleration
Recently I came across the following thought experiment :
Take a string and whirl it in a horizontal circle. Imagine that an ant is sitting on the string . From our point of view , the ant is in ...
0
votes
1answer
36 views
What is the name of derivation technique that uses finite/infinitesimal elements to derive formulas?
This may be a strange question but I have not been able to find the name of this derivation method after hours of Googling. I have seen this technique all throughout my undergrad and grad years in ...
1
vote
1answer
28 views
Maximum distance of a body in projectile motion from origin [duplicate]
Suppose a body is in projectile motion then what will be the maximum distance it can attain from origin?
Also in what case the range will be the maximum distance from the origin compared to other ...
0
votes
1answer
27 views
Velocity of an object orbiting on a string
First, I'm sorry if this question is dumb, incoherent or vague - I never really studied any physics and this might be out of my grasp, but I tried to apply some of the math I know and figure these ...
1
vote
1answer
33 views
Meaning of “a force that derives from potential energy”
In mechanics course, when the idea of equilibrium was introduced they included the idea of a force that derives from potential energy which is the force $F$ which is related to the potential energy $...
0
votes
0answers
13 views
Work of centrifugal force cartesian coordinates
Hey I have a question about an expression in the textbook of Born. There a pendulum of variable is considered. Then it is stated that for shortening a work given by
\begin{equation}
-ml \int \dot{\phi}...
0
votes
1answer
23 views
Relation of Corresponding principle and law of large numbers
Is it possible that Corresponding principle can be derived from the law of large numbers? Also is the principle a postulate of Quantum Mechanics?
0
votes
0answers
25 views
What is the lift coefficient of human body?
Assuming we can change angle of attack by changing our hands orientation what is the maximum aerodynamic lift coefficient of human body?
0
votes
1answer
25 views
How the length, flexural rigidity and position of attached mass affects the period of oscillaion of cantilever?
Hey everyone, I'm a highschool student from New Zealand and can someone please explained to me with physics principles in words:
Why increasing the length of cantilever increases the period of ...
1
vote
0answers
25 views
Query about why there is a torque on this spinning ring in a magnetic field
We learnt in class that the $\vec m\times \vec B$ is the torque of a current loop in a magnetic field. I was trying to understand this by considering the diagram above. Let the B field be pointing in ...
2
votes
1answer
55 views
Do canonical transformations form a group?
In a course on classical mechanics, we barely touched upon canonical transformations via generating functions. Just like Lorentz transformations form a group, I want to know if canonical ...
1
vote
0answers
21 views
+50
Unrelated states in virtual work
I'm reading the Wikipedia article on virtual work, and there is the following quote:
Consider now the free body diagram of a deformable body, which is composed of an infinite number of differential ...
1
vote
1answer
77 views
Accelerated frame vs gravity frame
Can accelerated frame change curvature of space as gravity does?
Can there accelerated frame be pure inertial frame?
0
votes
1answer
17 views
Time period of a body moving under central force in a circle [on hold]
It is given that a body of mass m with non zero angular momentum L under influence of gravitational force . if area of particle's bound orbit is A then find out time period of revolution
My approach ...
0
votes
0answers
18 views
Inertial frame definition in Rindler Introduction to STR vs Landau' & Lifshitz Mechanics
Juxtaposing Rindler's Introduction to STR (page 7) vs Landau's Mechanics (page 5) inertial frame definition,I get that rindler assumes frame moving uniformly w.r.t inertial frame as an inertial frame ...
0
votes
1answer
24 views
catenary equations solving for sag given distance and cable length
I know the distance between points, and the length of the cable between them, how can I calculate the sag?
How to solve this eqn for x = f(s,d)? since I know both s and d.
s = cable length = 2 * x * ...
0
votes
0answers
20 views
Lagrange Multiplier with inequality conditions
How can Lagrange multiplier method be used when inequality conditions are given instead of equality conditions?
1
vote
1answer
49 views
If a body is moving under central force in a circle then how its path will be changed if it is subjected to a impulse [on hold]
A particle of mass m moves under an attractive central force of $Kr^4$ with an angular momentum L
Find the frequency of the radial oscillations if the particle is given a small radial impulse and ...
0
votes
0answers
39 views
Examples of fallacies regarding physical phenomena ( laymen's, student's, philosopher's or even past physicists fallacies)? [on hold]
Apparently some fallacies can be made in physics, there are posts on this subject on this site : separation fallacy , equal transit time fallacy, thermodynamics fallacy. So this question may not be ...
1
vote
1answer
64 views
Confused concept of “ force” in ordinary language versus precise concepts in physics [on hold]
I'd like to be able ( for philosophical purposes) to illustrate this general idea : " science makes clear and precise concepts that are confused in ordinary/prescientific thought".
I think that a ...
0
votes
0answers
36 views
Microscopic explanation for Hooke’s law
This figure
shows the force between two atoms - at separation d there is no repulsive or attractive force, but for separation between d and the minimum, there is an approximately linear increase ...
2
votes
1answer
57 views
Liouville's integrability theorem: action-angle variables
For classical dynamical systems, let $I_{\alpha}$ stand for independent constants of motion which commute with each other. Pg 323 of Jose-Saletan and also 'Remark 11.12' on pg 443 of Fasano-Marmi's '...
1
vote
2answers
41 views
Do the terms “damping constant” and “damping coefficient” have standard uses?
I've heard the terms "damping constant" and "damping coefficient" used to describe both the $c$ from the viscous damping force equation $F = -c\dot{x}$ and the $\gamma$ from the definition $\gamma = \...
-1
votes
0answers
13 views
The variation of density of a liquid in a cylindrical container due to it's bulk stress [closed]
A vertical cylindrical vessel contains 1ltr. of water having column height of 60 cm. Density and bulk modulus of elasticity is given as 10³kg/m³ and 2×10^9 N/m² respectively. What will be the change ...
0
votes
1answer
62 views
Rotation of a Point Particle
I wonder if there is a meaning of rotation for a point particle.
Does a point particle have angular momentum and does he reply to torque?
0
votes
2answers
34 views
What is the direction of linear motion after this impact?
I've been thinking about a situation where I am not sure what the resulting motion would be.
This is what I am thinking,
1) P is the point of application of force. If there are two force components ...
6
votes
5answers
740 views
Alternative classical explanation of the Stern-Gerlach Experiment?
Many questions have been asked on this site about the Stern-Gerlach experiment, but as far as I can tell this one hasn't. Does the following classical explanation of the SG experiment work?
Model ...
0
votes
0answers
76 views
Angular acceleration of rotating sphere [closed]
As shown in figure there's a homogeneous solid sphere. It is rotating about axis which is passing through point P directed perpendicular to the plane of paper. (In short like a pendulum).
I'm ...
44
votes
7answers
8k views
Why does Taylor’s series “work”?
I am an undergraduate Physics student completing my first year shortly. The following question is based on the physical systems I’ve encountered so far. (We mostly did Newtonian mechanics.)
In all of ...
3
votes
1answer
67 views
What does Earth feel like when squeezed?
he average density is about 4g/cm^3 so if the earth was in the size of an orange, it would feel like a rather heavy ball.
The crust is relatively thin, and the earth is said to be solid land masses ...
1
vote
1answer
48 views
Euler-Lagrange Equation and moment of inertia
I'm self studying and having trouble with the following question:
"Consider a solid of revolution of a given height. Determine the shape of the solid if it has the minimum moment of inertia about its ...
0
votes
0answers
30 views
Under given conditions, is the probability of collision between two balls in a box greater than zero? How to prove it?
This is a question I've been thinking about lately.Maybe not very rigorous.
In a finite space, there's a finite number of, let's say, a cubic meter, and there's a million rigid bodies in one cubic ...
0
votes
1answer
33 views
When water flows over a curved surface, will it reduce the pressure on the curved surface? Is this because of the viscosity of water?
I think it's because water moves on a curved surface with centripetal force. Because the gravity of water provides centripetal force, the pressure of water on the curved surface is reduced. When the ...
0
votes
0answers
6 views
How do we define internal and external work?
I'm reading a text on the principle of virtual work and there are presented the following definitions for a deformable body:
Internal work = $\int_\Omega{\delta {\epsilon}^T\sigma d\Omega}$
External ...
-1
votes
1answer
29 views
Finding tangential and normal velocity from a curve [closed]
How do you find tangential and normal velocity from a curve?
I know how to find dy/dx, but I have no idea how to obtain ut and un and dv/dt.
0
votes
1answer
35 views
Oscillating problems [closed]
I am practicing for my "Mechanics of continuous media" exam.
There is two exercises I couldn't really do yet:
A homogeneous meter rod at the 70 cm line is hooked up, and making small amplitude ...
1
vote
3answers
110 views
How are classical and quantum momentum related in an intuitive manner?
I know that quantum momentum is inversely proportional to the wavelength of the probability or matter wave of a given particle, but I don't get how this relation of this abstract mathematical ...
0
votes
2answers
29 views
Torque and angular velocity in a lever
Let's consider a lever with an object with mass $m=1$ with distance $x$ from the fulcrum.
If the lever starts at rest and in a horizontal configuration, then in a $dt$ the object causes a $dv=gdt$, ...
0
votes
1answer
52 views
Change in momentum for gas particle collision with wall
I've attached the question as an image below as it's a graphical question.
It simply states:
"The diagram shows a gas particle about to collide elastically with a wall.
Which diagram shows the ...
0
votes
0answers
11 views
Relation between the dimensions of a pressurized cylinder and stress on its walls
I don't have much of a background in physics so apologies if i use the terms incorrectly. Given a pressurized cylinder, if the cylinder increases in length the stress on its walls doesn't change but ...
1
vote
1answer
38 views
A paradox about canonical transform preserving Poisson bracket?
Let $q,p$ denote the position and momentum. Consider a transform generated by $g$:
$q' = q + \epsilon \{q,g\}---(1a)$
$p' = p + \epsilon \{p,g\}---(1b)$
Then:
$\{q',p'\} = \{q,p\}+o(\epsilon^2)+\...
0
votes
0answers
13 views
Relationship between radius of Euler Disk and radius of path
Lets say you have a Eulers Disk of radius a which circulates at a
circle of radius R with an angle theta from the vertical, what is the minimum possible radius R of the circle in terms of theta and a?...
9
votes
1answer
88 views
Is it possible for a system to be chaotic but not ergodic? If so, how?
In a recent lecture on ergodicity and many-body localization, the presenter, Dmitry Abanin, mentioned that it is possible for a classical dynamical system to be chaotic but still fail to obey the ...
1
vote
1answer
69 views
Uncertainty principle in classical mechanics and quantum mechanics
I was just listening to the Leonard Susskind lectures on youtube on qunatum mechanics basics. He said that uncertainty principle in classical mechanics is completely different from that of quantum ...
1
vote
0answers
24 views
How principle of least action? [duplicate]
I had learned the principle of least action.But I didn't get the motive behind taking the least action. Or why should the particle follow a path where it have a least action?
3
votes
2answers
47 views
Derivation of Hamilton-Jacobi equation
I am trying my own way of deriving the Hamilton Jacobi equation
$$\frac{\partial S}{\partial t} = -H \tag{1}$$
through direct variation. I think the difficulty of doing this is that the upper limit ...
