Classical mechanics refers to the classical (i.e., non-relativistic, non-quantum) study of physics. Three major formulations of classical mechanics are newtonian mechanics, lagrangian mechanics, and hamiltonian mechanics. The latter two are rather useful in extensions to Classical Mechanics; ...

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Distance a curveball travels?

I've seen some discussions regarding the movement of a spinning object, say a curveball. However, all have been largely qualitative. I was wondering if anyone has seen or worked through a ...
0
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1answer
213 views

Violation of conservation of energy and potential energy between objects

I would like to clarify my question. I have numbered them to be independent questions For any conservative fields, $\vec{F} = -\nabla U$. Which means the restoring force is opposite to the ...
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2answers
3k views

Rolling resistance and static friction

I am a bit confused about the relation between rolling resistance and static friction. I have often heard that it is the static friction that lets the wheel roll. Consider the following two cases: ...
1
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1answer
226 views

Tolerance of Natural Frequency & Resonance?

I'm writing a report at the moment about natural frequency, driving frequency and resonance - and I was wondering, is there a typical % tolerance inside which the driving frequency will cause ...
1
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1answer
551 views

Gears and efficiency/speed

For Christmas me and my brother got an AR Drone, the propellers are on a large gear, which is rotated by a small gear that is connected to the motor. This means the small gear (and therefore the ...
2
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2answers
579 views

Does the potential energy of fluid rising on a string change?

Lets say I have a glass of water at rest. Then I go and hang a string above the water (vertically), such as the end of the string is immersed in the water. Over time some of the water is going to ...
3
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1answer
1k views

Is it possible to break bulletproof glass with your voice?

In The Adventures of Tintin, an opera singer (the Milanese Nightingale) broke a bulletproof glass case using her voice. Is that scientifically possible? From the Wikipedia page, a typical bulletproof ...
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1answer
699 views

Conjugate Variables and Fourier Transforms in Classical Physics

Let q be a generalized coordinate with a conjugate momentum p and a potential resulting in a periodic motion of q. What is the meaning of the Fourier transform of q(t) over its period? Can this be ...
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1answer
197 views

Determine the tensor of contraint and deformation of a cube under compression

We have a cube under compression with dimension l1*l2*l3, is put between 2 rigid plates in the axis 1 (two plates block the deformation of the cube in thí axis), the cube is also put on a rigid plate, ...
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2answers
442 views

Question Based On Galileo's Law Of Falling Bodies

Galileo discovered that the distance fallen is proportional to the square of the time it has been falling.Why is it proportional to the square of the time and not just time? i.e $d \propto t^2$ why ...
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2answers
2k views

How much effect does the mass of a bicycle tire have on acceleration?

There are claims often made that, eg, "An ounce of weight at the rims is like adding 7 ounces of frame weight." This is "common knowledge", but a few of us are skeptical, and our crude attempts at ...
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2answers
426 views

Spin angular momentum of a system of particles : Is there any energy associated with it?

Consider a system of point particles , where the mass of particle $i$ is $μ_i$ and its position vector is $\vec{r}_i$. Let $\vec{r}_\text{cm}$ is the position vector of the center of mass of the ...
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1answer
1k views

Converting angular velocity to linear velocity through friction

A very basic question here; it's related to this one, but not quite the same. If a rotating rigid body (a sphere for the sake of discussion) with mass $m$, radius $r$ and inertial tensor $I$ has ...
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1answer
884 views

What are examples of classical physical systems having polynomial observables of degree greater than 2?

Specifically: What are empirically well-understood examples of (integrable) Hamiltonian systems whose Hamiltonians include polynomial expressions, in the canonical coordinates $\{q^i,p_i\mid ...
2
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1answer
525 views

Thermal energy generated due to loss in kinetic energy when observed from two different frames of reference

A body is moving with a velocity $v$ with respect to a frame of reference $S_1$. It bumps into a very heavy object and comes to rest instantaneously, its kinetic energy $$\frac{1}{2}mv^2$$ as ...
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2answers
1k views

What are the expressions for rotational and translational kinetic energies of a system of point particles?

Consider a system of point particles , where the mass of particle $i$ is $\mu_i$ and its position vector is $r_i$. What are the expressions for translational kinetic energy and rotational kinetic ...
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5answers
516 views

Are Uncertainties in Measurements Important?

In the first lecture of MIT's Classical Mechanics Prof. Lewin highlights the importance of uncertainties in measurements by quoting "Any measurements, without the knowledge of uncertainty is ...
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3answers
97 views

I think there is something wrong with this problem. How do you know if the vertical acceleration is zero?

Suppose a block with mass 3kg is on a frictionless table and a force of 15N pulls it from an angle of 38 degrees above the horizontal. 1) What is the apparent weight of the block? 2) What is the ...
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2answers
167 views

Can we describe the classical laws of physics in a frame-of-reference-independent way?

First of all, I am not a physicist, so I cannot guarantee things I say will make sense. I will try my best, though. In classical mechanics we have the notion of inertial frame of reference. If my ...
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4answers
3k views

Define Pressure at A point. Why is it a Scalar?

I have a final exam tomorrow for fluid mechanics and I was just looking over the practice exam questions. They do not provide solutions. But pretty much I have to define pressure at a point and also ...
3
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2answers
2k views

How does the speed of an incoming pitch affect the speed of a baseball after it's hit?

Which will go further if a batter manages to hit it with a baseball bat: a baseball thrown to the batter at 90 miles per hour or one thrown at 60 miles per hour?
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8answers
3k views

Real world examples for projectile thrown upwards or downwards

I am preparing a physics course for high school about projectile motions. If a projectile moves with initial velocity $v_0$ in the gravitational field of the earth, the equation $$ s(t) = 1/2 g t^2 ...
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5answers
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What symmetry causes the Runge-Lenz vector to be conserved?

Noether's theorem relates symmetries to conserved quantities. For a central potential $V \propto \frac{1}{r}$, the Laplace-Runge-Lenz vector is conserved. What is the symmetry associated with the ...
4
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1answer
406 views

Some questions about the logics of the principles of independence of motion and composition of motion

In high-school level textbooks* one encounters often the principles of independence of motion and that of composition (or superpositions) of motions. In this context this is used as "independence of ...
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3answers
517 views

Calculating stress without strain

I am working on an algorithm for a real-time simulation. I would like to calculate to extremely permissive tolerances approximate values for the stress within a 2D geometry. It will not be difficult ...
2
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2answers
321 views

Why do balls in a spinning ellipsoid move to the minor axis plane?

There is a question concerning the Physics of a small child's tall that has been bothering me for some time now. I have investigated this to a small degree, but I have not been able to find a ...
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1answer
207 views

Is the number of independent constants of a system equal to the number of degree of freedom of it?

Maybe the question is not very clear myself since I am not a physics major.But can you help me make this question clearer and then give me some comments on it? I got that this holds in gravitional ...
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2answers
2k views

why is mechanical waves faster in denser medium while EM waves slower?

Why is it that mechanical waves/longitudinal waves/sound travel faster in a denser/stiffer medium as in steel compared to say air, while EM waves/trasverse waves/light travels slower in a (optically) ...
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5answers
1k views

Is it possible to recover Classical Mechanics from Schrödinger's equation?

Let me explain in details. Let $\Psi=\Psi(x,t)$ be the wave function of a particle moving in a unidimensional space. Is there a way of writing $\Psi(x,t)$ so that $|\Psi(x,t)|^2$ represents the ...
3
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2answers
4k views

Testing the temperature of an open flame

How, and what device do you need, to obtain the exact temperature of an open flame? For the purpose of this question, you wanted to maintain 375 degrees. You can control the flame, but have no idea ...
3
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2answers
661 views

What are some interesting coupled harmonic oscillators problems?

That I could create as a classical mechanics class project? Other than the classical examples that we see in textbooks.
2
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2answers
3k views

Dimensional Analysis: Buckingham Pi Theorem

I am studying for a fluids quiz and I am having a few problems relating to dimensional analysis but for the time being fundamentally I have a problem selecting the repeating variables. Like does ...
4
votes
1answer
229 views

Effect of rotation on turbulence threshold for Reynolds number?

If the significance of the Reynolds number is: Then what is the effect of angular momentum on the transition from laminar to turbulent as in a convective vortex? Waterspouts, in particular, seem ...
2
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1answer
856 views

Principle of Least Action; Newton's 2nd Law of Motion

This question is based on the description of Longair in his book "Theoretical Concepts in Physics". He starts by giving some provisions: Conservative force field Fixed times $t_1$ and $t_2$ Object ...
3
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2answers
455 views

What are some interesting calculus of variation problems? [closed]

That I could create as a classical mechanics class project? Other than the classical examples that we see in textbooks (catenary, brachistochrone, Fermat, etc..)
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3answers
229 views

Do we know how matter moves matter?

I was surprised when reading an apologetics book recently that attempted a rebuttal of the claim that "An immaterial mind cannot interact with the physical order." Here was the response: How could ...
4
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3answers
589 views

Ice cream cone and loop-de-loop

Was siting in class thinking about this problem, did some rough sketches of a solution but never really managed to solve it. Assume a boy starts at the top of a circle with radius R as described ...
31
votes
1answer
2k views

Why does this object periodically turn itself?

See this video about 30 sec in. http://www.youtube.com/watch?v=dL6Pt1O_gSE Is this a real effect? Why does it seem to turn periodically? Can it be explained by classical mechanics alone? Is there a ...
15
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4answers
2k views

Tree level QFT and classical fields/particles

It is well known that scattering cross-sections computed at tree level correspond to cross-sections in the classical theory. For example the tree level cross-section for electron-electron scaterring ...
0
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1answer
1k views

What happens to temperature when pressure is constant in a cylindrical piston of saturated liquid ammonia?

Let's say I have a cylindrical piston containing saturated liquid ammonia that is fitted with an electrical heater and a paddle wheel for stirring at an initial pressure and an initial temperature. ...
2
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1answer
303 views

How should a closed-ended terrestrial trajectory be corrected for the Coriolis effect?

I have tried verifying the numerical integration of the Coriolis effect for 1000 to 2000-yard rifle fire by switching ON/OFF the Coriolis correction of a good ballistic simulator program (PRODAS). The ...
2
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2answers
8k views

Book against a wall and forces

If you take a book with mass of 1kg and push it against the wall. With how much force do you have to push the book so it does not fall? The problem is I know how to calculate this problem, you say ...
1
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1answer
339 views

Proof of the Hydrostatic weighing equation?

I've been trying to derive this equation for about two hours: But I can't seem to get it. In my class, we are using it to accurately measure the volume of irregulary-shaped objects, but I ...
7
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2answers
1k views

How fast does force propagate through matter? [duplicate]

Possible Duplicate: Is it possible for information to be transmitted faster than light? Consider the following thought experiment. You have a long perfectly rigid beam (for the sake of ...
-1
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1answer
9k views

Finding induced current in a loop at an instant [closed]

I'm working on this problem; however, I cannot seem to get anywhere. Given information: The rectangular loop in the figure has 2.1x10^-2 ohm resistance. What is the induced current in the loop at ...
1
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1answer
878 views

Problems that Lagranges equations of the 1st kind can solve whereas the 2nd kind can't?

Can anyone give examples of mechanics problems which can be solved by Lagrange equations of the first kind, but not the second kind?
4
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1answer
139 views

A ball inside a cavity

Seems not a trivial problem: There is a semi-cylindrical cavity, with radius $R$ as shown in the Figure. A small ball (point mass for simplicity) with an initial horizontal velocity $v$ flies into ...
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2answers
1k views

Canonical momentum in different coordinate system

The canonical momentum is defined as $p_{i} = \frac {\partial L}{\partial \dot{q_{i}}} $, where $L$ is the Lagrangian. So actually how does $p_{i}$ transform in one coordinate system $\textbf{q}$ to ...
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1answer
374 views

centrifugal force in static frame of reference

The other day we derived Kepler's third law. $$ \left( \frac{T_1}{T_2} \right)^2 = \left( \frac{r_1}{r_2} \right) ^3 $$ In order to derive this, you can look at a given planet that revolves around ...
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0answers
312 views

Error caused by pulley eccentricity [closed]

Not sure if this is perfectly a physics question: A rope is wrapped around a cylinder of diameter D. The cylinder is slightly eccentric so that the distance between the axis of the cylinder and the ...