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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].

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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 $...
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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}...
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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?
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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?
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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 ...
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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 ...
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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 ...
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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 ...
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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?
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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 ...
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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 ...
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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 * ...
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0answers
20 views

Lagrange Multiplier with inequality conditions

How can Lagrange multiplier method be used when inequality conditions are given instead of equality conditions?
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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 ...
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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 ...
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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 ...
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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 ...
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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 '...
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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 = \...
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0answers
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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 ...
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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?
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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 ...
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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 ...
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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
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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.
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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 ...
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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 ...
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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 $dv=gdt$, ...
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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 ...
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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 ...
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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)+\...
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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
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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 ...
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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 ...
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0answers
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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?
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2answers
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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 ...