Mechanics Definition and 999 Threads

We know that energy is a function of space and velocity and it’s constant (in ideal case) though time. So ## E(\vec{x}(t) , \vec{\dot{x}}(t)) = E_0## where ##\vec{x} , \vec{\dot{x}} \in \mathbb{R}^3##. So my function is ##E : \mathbb{R}^6 \rightarrow \mathbb{R}##. Then there is my question...

hi, I’ve been walking through posts on this forum, and found plenty of book recommendations for QM. My problem is, I haven’t had enough practice in a long while. I could go over Solved Problems in e.g. Galitsky, or Gasiorowitz, but they seem to be a little far from what I want to test...

Homework Statement A force is applied tangentially to a rigid body on a horizontal surface.if it doesn't slip find the frictional force https://ibb.co/m9sMEU Homework EquationsThe Attempt at a Solution The solution tells us to take axis about the bottommost point in contacy with the surface...

Homework Statement Using log taylor expansion to express cumulants in terms of moments I have worked through the expansion- ##log(1+\epsilon)= ...## see thumbnail- and that's ok; my question is why does the expansion hold, i.e. all i can see is it must be that ##k## is small- how is this...

Hi! As the title suggests, I am searching for some good problem books with really challenging problems for classical physics, more precisely on the topics of electricity and elecromagnetism, geometrical optics and wave optics, thermodynamics and analytical mechanics. When I say challenging I...

Any good lecture notes for classical mechanic?

Hi, guys I have posted this question on StackExchange, but no one seems to care answer. Because I don't think this is a simple textbook question, I start my thread here: I know this is a big question. But as a graduate student, my research is somehow related to nonequilibrium...

All the literature on the quantum eraser that I've seen is grounded in the Copenhagen interpretation of quantum mechanics. It's very easy to understand the experiment in those terms. Do you know how quantum eraser experiments are interpreted by the de Broglie–Bohm theory? What is erased in this...

Homework Statement A block is acted on by a spring with spring constant k and a weak friction force of constant magnitude f . The block is pulled distance x0 from equilibrium and released. It oscillates many times and eventually comes to rest. Show that the decrease of amplitude is the same...

Greg Bernhardt submitted a new blog post Servo-Constraints in Mechanics Continue reading the Original Blog Post.

This is A very general question. I will be taking physics 112 at Cal (in the future) which is basically stat mech. Almost all professors use Kittel and Kroemer but I’ve heard it’s god awful (I can attest to this having read a little myself). Does anyone know of a secondary textbook that is of...

Bohmian mechanics requires a preferred reference frame. But String theory doesn't have any preferred frames, so isn't BM incompatible with ST?? Maybe it would be compatible with other theories of quantum gravity that permit a preferred frame (LQG, CDT)...

We experimented with the Maxwell's wheel today and at the end we were asked about why does this apparatus stop since there is conservation of energy. I did some research and apparently there is a type of friction called "rolling friction", wikipedia defines it as "the force resisting the motion...

The building of theoretical mechanics can be constructed using only the first and the second derivatives (those of coordinates in case of kinematics: velocity and acceleration and those of energy in case of dynamics: force and gradient thereof). It is obviously unavoidable if one wants to deal...

Hi all, I am rather confused about the following concept. Assistance is greatly appreciated! A time-dependent probability amplitude can be written as $$\langle a_k| e^{-\frac{i}{\hbar}\hat{H}t} |\psi\rangle$$ where ##a_k## is an eigenvalue. Suppose I want the x-representation of the ket, I can...

Hello :smile: When we are walking, exist, basically, three forces on us foot.(gravity, normal and friction forces). Considering that the frictional force is in static regime, the resulting force is 0. Theoretically, there is no relative movement between the foot and the floor. So my doubts: How...

Homework Statement Find v(θ), the dependence of the speed of the object on the angle θ. The string is ideal and there's no friction. Homework Equations - The Attempt at a Solution I'm quite sure I should use the conservation of energy mgh = mv2/2, but I don't know how to express h with the...

1. A block of Mass 'm' is connected to another block of Mass '2m' through a weightless pulley by a weightless inextensible thread of length 2l. The left block(mass=2m) rests on a table at a distance l from its edge, while the right block is kept at the same level so that the thread is...

Hello there, I am a new member looking to gain more knowledge on physics...

Homework Statement Hi all, I'm having trouble working on the following problem. Any assistance will be greatly appreciated. Here, the capital letters stand for Position and Momentum operators while the ##x', p'## stand for eigenvalues.Homework EquationsThe Attempt at a Solution a) and b) It...

I came across this article at physicsworld.com which has the headline "Quantum mechanics defies causal order, experiment confirms". https://physicsworld.com/a/quantum-mechanics-defies-causal-order-experiment-confirms/ The actual experiment is described here: https://arxiv.org/abs/1803.04302 I...

I have started going through the Quantum Mechanics 8.04x and 8.05x from MIT in edx by prof. Barton Zwiebach. I am enjoying them. 8.04x 1. https://courses.edx.org/courses/course-v1:MITx+8.04.1x+3T2017/course/ 2. https://courses.edx.org/courses/course-v1:MITx+8.04.2x+3T2017/course/ 3...

Hi. I want to learn - amateurishly - Quantum Mechanics, and General Relativity, but my experience with Physics is very small. I want to ask, what should I learn - what books should I read - before I start to learn those theories? Sorry for my english.

I liked his Group Theory book. Now he wrote a QM book. No-Nonsense Quantum Mechanics: The Ultimate No Holds Barred Guide To The Quantum World

Let's say we want to change a wheel in a car. We want to remove bolts fastening the wheel using this tool: I have also drawn a diagram of the forces in operation: Now, from experience I can say that the point of rotation of the wrench will be the blue point. Now, trying to determine the...

Bohmian mechanics claims that although it is deterministic, randomness emerges from the fact that we cannot know the initial conditions of the particle due to Heisenberg's uncertainty principle. However this experiment can put that to the test and determine whether randomness in quantum...

Homework Statement Homework Equations The Attempt at a Solution [/B] My questions: 1. By resultant force, does that mean the force exerted on the side of the water + force exerted on side of the oil? Because I'd think that the force on the side of the water would be different than the...

These images have been taken from Goldstein, Classical Mechanics. Why do we need Lagrangian formulation of mechanics when we already have Newtonian formulation of mechanics? Newtonian formulation of mechanics demands us to solve the equation of motion given by equation 1. 19. for this we need...

I have been going through problems in my textbook and have a question. The chapter is on gravitation and orbital mechanics. When answering the problems I seem to head towards different methods than what the book prescribes. My answers, primarily using known orbital equations, are close, but not...

Homework Statement What will momentum measurement of a particle whose wave - function is given by ## \psi = e^{i3x} + 2e^{ix} ## yield? Sketch the probability distribution of finding the particle between x = 0 to x = 2π. Homework Equations The Attempt at a Solution The eigenfunctions of...

A mass m is tied to a string which is wrapped to a twig of a tree. How many minimum times should we wrap the string so that it doesn't fall? Here is what i got... 1.There is friction between the twig (or fixed cylinder) and the string. 2. if the total friction between the string wrapped around...

Homework Statement A mechanical servo-mechanism comprising of a movable piston-cylinder within a vertical cylinder operates based on a venturi contraction in a horizontal 350mm diameter pipe that delivers a fluid of relative density 0.95. The upper end of the 100mm diameter vertical cylinder is...

Hello! I got a bit confused about the fact that the whole the description of spin (and angular momentum) is done in the z direction. So, if we are told that a system of 2 particles is in a singlet state i.e. $$\frac{\uparrow \downarrow -\downarrow \uparrow }{2}$$ does this mean that measuring...

Rehashing this topic because I believe a clear misconception is stated in many threads. Classical mechanics is an incorrect ( by the definition of correct ) theory which is only an approximation that uses incorrect assumptions ie. Constant time but yet makes accurate predictions in its regime...

I’m a high school student reading through Young and Freedmans University Physics. The book has gotten my very interested in classical mechanics, and I wish to read more about it outside the textbooks. However, I don’t know where I can read more about it. Sure, there are books that I can read...

I'm trying to think through a situation, and develop some confidence I've got it right. The situation is a apartment building, about 60'/20m high, with a courtyard in the middle about 60'/20m square. In the middle of the courtyard, is an low exhaust stack, about 8' high and around 8' square...

Hello, this is my first question on PhysicsForum. I am primarily interested in statistics/machine learning. I have recently discovered that many of the ideas used in machine learning came from statistical physics/ statistical mechanics. I am just wondering if it's a bad idea to attempt to learn...

Homework Statement Refer the given image. [Prob 2.9] Homework Equations F=ma The Attempt at a Solution I drew the normal vector perpendicular to the surface of the cone and resolved it as ##Nsin\theta=mg## ##Ncos\theta=\frac {mv_{0}^2} {r}## where ##v_{0}## and ##r## are the speed and radius...

Homework Statement Two blocks with pulleys attached lie on a frictionless surface and are connected by a massless rope strung over the pulleys as shown at right. A force of magnitude F is applied to the second block. Draw a FBD for a system consisting of Block 1 and its pulley, and also a...

Hi everyone, I have a real life fluids problem I am trying to solve theoretically. During a commissioning exercise we needed to discharge fuel into a 100L steel drum to test flow rates for a new re-fuelling skid. To minimise turbulent flow and static build up a drop pipe was used for the hose...

Hi. I just received a copy of Ballentine's "Quantum Mechanics: A Modern Development" ordered from Amazon, after I heard well of it in this site. I'm wondering what edition I've bought: the one I've got has a white hardcover, and its ISBN is 9789810227074. Does someone ever used this edition? Why...

I always think about entanglement as pure conservation of energy and conservation of angular momentum. In fact I see that only conservation of energy is non-local, and that quantum objects have nothing to do with non-locality, for example you can entangle 2 atoms that have never interacted with...

Greg Bernhardt submitted a new PF Insights post Orbital Mechanics in Unity Game Engine for Augmented Reality Continue reading the Original PF Insights Post.

I recently watched a video where Sean Carroll talked about QM and multiverses 1/ Could you please explain: Where does all the energy come from to drive all these universes. Surely this must take an enormous amount of energy to drive a multiverse system (infinite). Does each universe...

Homework Statement A particle is moving parallel to x-axis in the positive direction with velocity v such that at all the instants the y -axis component of its position vector is constant and is equal to 'b'. Find angular velocity about origin. Homework EquationsThe Attempt at a Solution I...

They found an underground lake on Mars last week! Given that the lake exists and is actually liquid (and has a surface), two obvious questions come to mind: 1. Will I be able to beet my earthly current record in bouncing a pebble there? 2. If I release a pebble from a given height here and...

Homework Statement Homework Equations orthogonality condition: that means that the point of ICR is orthogonal to the velocity Vb and Va The Attempt at a Solution the solution that i found with the problem is: The ICR of the bar is at infinity. the motion of the bar is translational. I think...

Homework Statement A solid disk of mass M and radius R is on a vertical shaft. The shaft is attached to a coil spring that exerts a linear restoring torque of magnitude Cθ, where θ is the angle measured from the static equilibrium position and C is a constant. Neglect the mass of the shaft and...

I have been taking many online courses. In the prerequisites for many courses, it has been mentioned, "basic" quantum mechanics. It has become important to define where the boundary of basic ends and the advanced level starts, though I believe that is not well defined. I have been studying QM...

Supposing the Many Worlds interpretation of QM is true... If a branching occurs during what we perceive is a wave function collapse, why would this be perceptible to us as probabilties? Wouldn't we just branch, leaving it just as imperceviable as the passage of time? That is, it just happens...