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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Equations of motion for bob-on-a-string — am I missing some terms?

The dynamics of a type of physical system I am currently working on are modeled in most of the literature by replacing the moving parts of that system with an equivalent set of pendulums. Parameters ...
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2answers
94 views

Need an intermediate resistivity part/material

I need a part or material for a planned experiment (the experiment is similar to those described in my articles http://arxiv.org/abs/1208.0066 and http://arxiv.org/abs/1109.1626 ). The problem is that ...
2
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1answer
69 views

Energy in a wind instrument?

My physics teacher said that he saw a guy playing a very large wind instrument on TV, and the guy apparently calculated that the total energy present in the instrument when he was playing was almost ...
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1answer
132 views

Is there a difference between, static loading and fast loading of a polymer (non linear elastic material) in terms of elastic potential generated?

Imagine a non-linear elastic material such as a rubber band, nylon webbing or polyester webbing tensioned between two points. Scenario 1: A large mass is statically (no acceleration) loaded onto the ...
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2answers
137 views

Magnitude of force to keep stick in equilibrium [closed]

Problem statement A straight and homogenous stick with mass m is pressed against a wall with the force F. The stick is horizontal perpendicular against the wall. Given that the friction between the ...
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3answers
434 views

Principle of Least Action via Finite-Difference Method

I am reading Gelfand's Calculus of Variations & mathematically everything makes sense to me, it makes perfect sense to me to set up the mathematics of extremization of functionals & show that ...
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1answer
160 views

Energy of a cylinder rolling down a path

Problem statement: A cylinder rolls without slipping down a hill. It is released from height h. What is its speed when it come down? The cylinder mass may be completely concentrated on the radius R, ...
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0answers
84 views

Relation between the period of rotation and the period of revolution of a satellite

I read somewhere that the tidal forces between the earth and the moon causes the equality between the 2 periods of the moon and that every planet-satellite system will evolve to this condition (like ...
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2answers
372 views

6 Story Building Swaying, Normal? [closed]

Preface: I'm currently sitting at my desk on a 5th floor in a South Florida office building, as I was earlier this morning when I felt the building sway slightly. It wasn't continuous and the ...
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0answers
127 views

Small unclarity in proof of Noether's Theorem

I'm trying to understand the proof of Noether's Theorem in my Classical Mechanics class. We formulated it as follows: A continous symmetry is defined as a flow $\phi^{\lambda}(q(t))$ which leaves the ...
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1answer
352 views

Buoyancy Problem - Cubes in water

I have a tank with water (10 m high) , with an ideal seal at the bottom (water can't fall down, but can enter bodies). I have a system of 6 cubes ( of polystyrene density= 20 Kg/m^3) with dimension ...
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1answer
137 views

Is there a trajectory which is not a solution of the equation of motion but satisfies all conservation laws?

I'm wondering whether conservation laws are sufficient to imply equations of motions. Specifically: 1) In classical mechanics of point particles, are conservation of energy, conservation of momentum ...
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468 views

Classical/Quantum Coin Toss

I am having a brainfreeze moment and have confused myself, help appreciated! Classical Coin: Heads OR tails. Quantum Coin: Superposition Heads AND Tails. Classical Mechanics: Deterministic (in ...
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41 views

Calculate the acceleration of the trailing muon bunch

Two separate suitably short but intense bunches of muons, "A" and "B", are both supposed to be constantly accelerating (in an otherwise sufficiently flat region) with constant proper acceleration ...
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3answers
538 views

How many points are required to make a black box

I have a black box with an arbitrary mass distribution inside it. I want to replace that object with n point masses without changing any mechanical properties of the box (center of mass, total mass, ...
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3answers
1k views

How much torque does it take to turn a doorknob? [closed]

How much torque does it take to turn a doorknob? I'm not looking for an exact answer, just a ballpark for someone who doesn't have a sense of everyday amounts of torque. Here's a very ordinary ...
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0answers
55 views

Hamiltonian system: match transformations and constants of motion

I have a problem about the interpretation of an exercise. Given the following Hamiltonian $$H=\frac{\mathbf{p_0}^2}{2m}+\frac{\mathbf{p_1}^2}{2m}+\frac{\mathbf{p_2}^2}{2m}-2V(\mathbf{r_1}- ...
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0answers
84 views

A quicker way to verify that a function is a constant of motion?

I have three particles that we can indicate with $\alpha$ ($\alpha$=0,1,2), they are identified by the $r^i_\alpha$ coordinates and $p^\beta_j$ conjugata momenta ($\beta=0,1,2$ and $i,j=1,2,3$). I ...
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2answers
302 views

How to calculate pressure exerted on the wheels of a robotic car?

I need some help in designing my robotic car. So its going to have 4 wheels, each driven by a 12-volt motor. It occurs to me that the weight of the chassis itself will exert some pressure on the ...
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0answers
260 views

Dose the gravitational force produces precession in the spinning top?

I'm new at classical mechanics but the text book says there is the torque in the spinning top which generated only by gravitation. It is hard to explain the situation, I've add the link. ...
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2answers
120 views

Hamiltonian equations: can I divide a solution of motion for a constant?

I'm solving an exercise about Hamiltonian equations. I have followed the proceeding below. The results given by the book are different to mine because its first result is the half of mine (and the ...
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1answer
210 views

Solving equation of motion of two massive particle exerting the gravitational force each other

I'm trying to analyze the motion of the particles which exert the gravitational force each other. Let $M_1$, $M_2$ be the masses of the particles, and the equation of motion of particle $M_1$ $$ ...
6
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2answers
2k views

Which is more efficient: a larger wheel or a smaller wheel?

I'm designing a 2-wheeled cart that I plan to rig to a donkey for hauling work around a farm. I'm wondering if there are mechanical advantages to using smaller wheels (like 40 cm diameter) vs. using ...
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10answers
3k views

What is the Earth truly rotating about/revolving around?

Earth rotates on its axis and revolves around the sun, the sun revolves around the galaxy, the galaxy is also moving. So Earth's net rotation as observed from a fixed inertial frame consists of all ...
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3answers
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Google interview riddle and scaling arguments

I am puzzled by a riddle to which I have been told the answer and I have loads of difficulties to believe in the result. The riddle goes as follows: "imagine you are shrunk to the size of a coin ...
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1answer
200 views

What are the physics behind the Coriolis effect? [closed]

What causes the Coriolis effect?
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3answers
452 views

Addes mass forces: can a force depend on acceleration?

My friend and I had a little discussion about added mass forces. I always interpreted $F=ma$ as a cause-effect relationship, so I find rather uneasy to accept that the cause can instantaneously ...
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1answer
54 views

Doubt about coordinates and point of equilibrium

I'm solving an exercise about small oscillations and I have a doubt about coordinates that I have to use. This is the text of the exercise: "A bar has mass M and lenght l. Its extremity A is hooked ...
2
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1answer
213 views

A different proof for 6 degrees of freedom

I want a different proof of 6 degrees of freedom of a solid object made of $\ N$ particles. I am thinking along these lines: Definition of rigid body is $\ modulus[\vec{r_i}-\vec{r_j}]=constant \ ...
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2answers
385 views

Rotating spring system: Is my intuition correct?

Consider a solid spherical object of uniform density that is rotating on an axis A1. Perpendicular to that axis one can draw another line that passes through the sphere. On this axis, on both sides of ...
3
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4answers
1k views

Can Newton's laws be explained by Quantum Physics? [duplicate]

I have only basic knowledge of physics. Could you please explain to me if a "Quantum" laws can theoretically (perhaps in the future?) be used to explain everything in macro levels? I'm having ...
0
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1answer
59 views

Something about collision [closed]

A sphere P of mass m, travelling with speed $u$, makes a head-on collision with a stationary sphere Q also of mass m. After the collision, the velocities of P and Q are $v_1$ and $v_2$ ...
9
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3answers
756 views

What happens when a ball stops bouncing?

If I were to drop a bouncy ball onto a surface, each successive bounce will be lower in height as energy is dissipated. Eventually, however, the ball will cease to bounce and will remain in contact ...
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2answers
21k views

Conceptually, what is negative work?

I'm having some trouble understanding the concept of negative work. For example, my book says that if I lower a box to the ground, the box does positive work on my hands and my hands do negative work ...
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2answers
230 views

Deriving $T = F\ r = I\alpha$ for a rigid body

For a single point mass : $\tau=F_{t}r=ma_tr=(m r^2)\alpha = I\alpha$ For multiple point masses bound together : $\sum \tau_i = (m_ir_i^2)\alpha = I\alpha$ But how do we go from that to $I\alpha = ...
3
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1answer
529 views

Intuitive explanation for why same force applied farther from a hinge causes larger angular acceleration than if applied closer?

A standard example of a problem involving torque is opening a door - the same force F applied far from the hinge causes a larger angular acceleration than if applied close to the hinge. I always had ...
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0answers
68 views

Finding the force of an object? [closed]

Sorry if my initial question was seen as a "homework question" but I don't really know how to go about asking this type of question. I have a feeling I have to use Newtons law but there is no ...
2
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2answers
1k views

Getting started with Landau Physics course [closed]

I want to learn Physics in my own time. I am an electrical engineer, working in the same field and am tremendously interested in Physics. I have heard a lot about the 10 book series of Landau ...
1
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1answer
281 views

Inclined plane question [closed]

An object, mass $m$ is placed on an incline, angle $\theta$. System is at equilibrium. coefficients of static and kinetic frictions are $\mu_s$ and $\mu_k$ respectively. Then: 1) What is the Total ...
2
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1answer
145 views

What is the distance traveled

the red dots represent a side view of path traveled, F is downward force and the tool used here is a pen placing parallel to the coin I have newly started to study mechanical physics. based on study, ...
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2answers
387 views

Wave function interpretation $y(x,t) = (0.35m)\sin(10\pi t-3\pi x + \frac\pi{4})$

Wave function interpretation $y(x,t) = (0.35m)\sin(10\pi t-3\pi x + \frac\pi{4})$ I used to deal with function with one variable And now theres are two, how can I interpret them? Is $10\pi$ still ...
4
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2answers
302 views

Why are some jenga pieces easier to remove than others?

Jenga is a game place with wooden blocks stacked on top of one another in an alternating pattern. Players take turns removing blocks from any layer and placing them on top. As the game progresses ...
0
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1answer
489 views

if a simple pendulum is dropped in a elevator with a acceleration greater than acceleration due to gravity then what will be its frequency

if a simple pendulum is dropped in a elevator with a acceleration greater than acceleration due to gravity then what will be its frequency ? We know time period depends on frequency.
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1answer
158 views

Another Inclined plane question

I did the FBD, and I found too many variables which are not eliminating...Moreover, I believe this question is based on kinetic and static friction. But, $\mu$ here is ambiguously defined...How Do I ...
2
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6answers
612 views

Centripetal Force Acceleration

In uniform circular motion, acceleration is $\frac{v^2}{r}$ and time which it acts $\rightarrow 0$. So $\Delta v = 0$, but then why/how does direction change, when the acceleration should be ...
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1answer
82 views

How large of a solar sail would be needed to travel to mars in under a year?

I'm attempting to approach this using the identity $$F/A = I/c$$ I can solve for Area easily enough $$A = F(c/I)$$ and I know the distance $d$ is $$d=1/2(at^2)$$ But I'm having difficulty trying to ...
4
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1answer
171 views

Peculiar Hamiltonian Phase space

I was solving an exercise of classical mechanics : Consider the following hamiltonian $H(p,q,t) = \frac{p^2}{2m} + \lambda pq + \frac{1}{2}m\lambda^2\frac{q^6}{q^4+\alpha^4}$ Where ...
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0answers
364 views

Why is the angle of impact complementary to the angle of launch in the simple equations for the range of a projectile?

I'm using the standard equation for the range of a projectile: \begin{align} d &= \frac{v\ \text{cos}\theta}{g} \left( v\ \text{sin}\theta + \sqrt{v^2\ \text{sin}^2\theta + 2gy_0}\right) ...
5
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3answers
1k views

Physical interpretation of Poisson bracket properties

In classical Hamiltonian mechanics evolution of any observable (scalar function on a manifold in hand) is given as $$\frac{dA}{dt} = \{A,H\}+\frac{\partial A}{\partial t}$$ So Poisson bracket is a ...
2
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1answer
81 views

Physics of a cold and hot top

Imagine two tops made up of exactly one thousand atoms. One is kept at 4 degrees Kelvin, the other at room temperature. 1. Would they weigh the same given an arbitrarily precise scale in the Earth's ...