Mechanics Definition and 999 Threads

If a suspended pendulum bob is accelerated (in a car, for example), if you're in the accelerating frame of reference, you will observe the fictitious force which appears to act on the bob (as you're in the accelerating frame, the bob is not 'moving' so to speak, so to establish equilibrium you...

Homework Statement A block slides down a frictionless incline (30 degrees above horizontal) for L=1.4m until it meets a horizontal surface with coefficient of kinetic friction 0.3 before coming to rest. Use work and energy to find the distance that the block slides on the horizontal surface...

Hello everyone! I am working on a quantum mechanics research paper and I need to interview one person. It can be electronically or even in a place like this. I just need one person to answer a few simple questions and to describe their qualifications that prove they are a reliable source for...

Homework Statement There is a metal stick that is connected to the ceiling with another one. The angle between them is 60°. Calculate the tension force of the bottom one. Homework Equations T = f N or actually none, except trygonometry The Attempt at a Solution [/B] I tried using this...

Homework Statement A disc is free to rotate about an axis passing through its center and perpendicular to its plane. The moment of inertia of the disc about its center is I. A light ribbon is tightly wrapped over it in multiple layers. The end of the ribbon is pulled out at a constant velocity...

Hi everyone, First post here. Been out of school for a while and quite rusty, but always had an interest in physics, and was pretty good back in the day. Can anyone help me understand the physics of fishing rods? How to look at a fishing rod in terms of physics and mechanics? (i.e. is it a...

Hi , The Static Friction force of an object on a ramp(inclined plane) making an angle with the horizontal is greater than the weight component down the ramp. My textbook says that this means that the object on the ramp is stationary as the frictional force is greater than the weight component...

1. Problem A boatman crosses a river of width ##D## from a point ##O##, looking to get to point ##A## on the opposite riverbank. Suppose that the flowrate is uniform with velocity of magnitude ##v_0##. The boat has a velocity ##\vec{v_1}## relative to the water, with constant magnitude, and it...

Homework Statement A uniform chain of mass 'm' and length 'l' rests on a rough incline (inclination is angle 'Q') with its part hanging vertically. The chain (inclined) starts moving up the incline (and the vertical part moving down) provided the hanging (vertical) part equals to 'n' times...

Homework Statement Find the velocity ± and the position x as functions of the time t for a particle of mass m, which starts from rest at x =0 and t =0, subject to the following force functions: (a) Fx = F0 + Ct (b) Fx = F0 sin Ct Ct (c) Fx = F0e^ct where F0 and c are positive constants...

Homework Statement This is more of a question of applying the correct principles to a range of problems involving a horizontal rod hinged to a wall that is then supported by another rod. The support rod is also attached to the wall from above or below and then attached to the horizontal rod, so...

1. Homework Statement Question attached. I am looking at the second line limit ##\beta (h/2\pi) \omega << 1 ## 2. Homework Equations above 3. The Attempt at a Solution Q1)In general in an expansion we neglect terms when we expand about some the variable taking small values of the...

Greg Bernhardt submitted a new PF Insights post Statistical Mechanics Part II: The Ideal Gas Continue reading the Original PF Insights Post.

Let's consider a particle moving along x – axis, its position at t = 1s is 1m and speed is 1 m/s. How can one calculate acceleration on the basis of this information?

Homework Statement Homework Equations Moment of inertia Torque Angular momentum The Attempt at a Solution I think I can understand the physics of the situation. There will be a torque on the bus due to gravity while the back of it remains in contact with the cliff and it will start to rotate...

Homework Statement The question is in the attached document Homework Equations Newton's second law states that F=ma Charged particle in magnetic field experiences F=Q ( v X B) The Attempt at a Solution Since the charge 'Q' is constrained to move along a path in xy-plane in such a way that the...

The question is prompted by a claim raised in another thread that "There is good reason (theoretically) to believe that linearity fails at high enough energies." I've put this with an A prefix because it is going to be about some damned difficult maths, I know. But please try to avoid the...

Homework Statement "...you were presented with a geologist at the bottom of a mineshaft next to a box suspended from a vertical rope. The geologist sent signals to his colleague at the top by initiating a wave pulse at the bottom of the rope that would travel to the top of the rope. The mass of...

Hello PF, I am currently taking a course on quantum mechanics that is following Griffiths' textbook (page by page). The first exam in the course coincided with two other courses (analysis and probability theory) and so I did lack a bit of training while doing it (the required material was from...

Homework Statement So I've been stuck on this exercise for a few hours now, maybe you can help out: 3 balls meet at the same height hm. Ball 1 is accelerated straight up into the air for 1s from height 0. When the acceleration stops, ball 2 is launched straight up from height 0 with v2 =...

Homework Statement This is a practice olympiad problem A light rod with length l is hinged in such a way that the hinge folds in one plane only. The hinge is spun with angular speed ω around a vertical axis. A small ball is fixed to the other end of the rod. (a) Find the angular speeds for...

Good morning. The question of the "continuous" or "discrete" nature of the universe is the subject of diatribe among the greatest physicists in the world. I would like to discuss the same topic, but asking a question about the aspect of continuum in classical mechanics. The use of mathematical...

I am looking for an undergraduate textbook on Classical Mechanics that includes Hamiltonian and Lagrangian formulations. One reason for this is that I am interested in quantization and second quantization. It should include treatment of harmonics oscillators. Thanks!

Homework Statement Consider 2 balls A,B on the same line . and they are connected to a third one G with a rope L. AG, AB. now the system monves in the effect of the mass of G and its projection to the line AB is in the middle. No friction. mass of A=mass of B=m and mass of G=2m .FInd the time...

Homework Statement Consider 2 balls A,B on the same line . and they are connected to a third one G with a rope L. AG, AB. now the system monves in the effect of the mass of G and its projection to the line AB is in the middle. No friction. mass of A=mass of B=m and mass of G=2m .FInd the time...

Something that has always been off for me is the canonical pedagogical treatment of analysis of trusses in the course typically called "Engineering Mechanics: Statics". Certainly, every cantilever bridge I see has completely attached joints, although lately I have seen some airy, open...

Consider the following examples: 1) combine a spin 1/2 state (with 2D Hilbert space and three spin 0 states (each with 1D Hilbert space). The resultant state is in 3D Hilbert space. 2) combine the same spin 1/2 state (with 2D Hilbert space and one spin 0 state. The states in (1) and (2)...

The term "state" in quantum mechanics is not generally agreed across the physics community. Some physicists consider it to be synonymous with "state preparation procedure". Others find this too restrictive, as it would exclude states not prepared in a laboratory. For example my nose is not...

Homework Statement [/B] Homework Equations - The pressure drop equation. [/B]The Attempt at a Solution

Is it possible for me to do cosmology and quantum mechanics as a joint degree at uni? If so where and does it cost extra? I’ve been wondering for a whole and I’m not sure where to look.

I am currently going through a friend's Mechanics II notes and homework before I take the course at a different university next semester. I have a few problems that I am having trouble understanding and am posting here for help. 1. Homework Statement 1. A solenoid is on, Flux is Φ. 2. The...

Homework Statement Find reactions at ends and deflection at C Homework Equations RA + RE = 115kN ##\delta##Total = ##\sum## (PiLi)/(AiEi) The Attempt at a Solution RA + RE = 115kN Then apply superposition: (Get rid of RE) divide whole member into 4 elements and add. ##\delta##Total =...

I am going to be doing a high school senior research project on how Quantum Physics will change the world in the future. Basically my current idea is to describe what quantum mechanics is, and then give examples that I explain and I state how they will change the world and the estimated time...

Homework Statement I am given the Hamiltonian of the relativistic free particle. H(q,p)=sqrt(p^2c^2+m^2c^4) Assume c=1 1: Find Ham-1 and Ham-2 for m=0 2: Show L(q,q(dot))=-msqrt(1-(q(dot))^2/c^2) 3: Consider m=0, what does it mean? Homework Equations Ham-1: q(dot)=dH/dp Ham-2: p(dot)=-dH/dq...

Homework Statement Hi all, I'm working on the following problem and would like some help. Many thanks in advance! The Figure below presents the Mach-Zehnder interferometer with an additional phase shift element in the upper path. $$\left( \begin{array}{cc} e^{i\phi} & 0 \\ 0 & 1 \end{array}...

Homework Statement Consider the system of two large, identical Einstein solids, each with oscillators, in thermal contact with each other. Suppose the total energy of the system is 2 units of the energy quanta, i.e., =2ℏ, (i) how many MACRO-states (e.g., one macro-state corresponds to one...

Hi all, I have a problem trying to interpret the mathematics of this experiment and would like some help. I think it's best I write out all my ideas (and misconceptions) so that I can be corrected. An illustration of the setup is below. Thanks in advance for any assistance! Let the following...

Homework Statement B is 10kg C is 20kg can I find a lagrangian for this system? If so how? Diagram: http://imgur.com/j811rzw Homework Equations L=T-V Kinetic = .5mv^2 Potential = mgh The Attempt at a Solution I know the kinetic energy must be 0 right? How could I find the potential?

Hi, I have read some on the PDEs for fluids, and particularly for rogue waves, where for instance the extended Dysthe equation and the NLSE look rather intimidating: Take for instance the Non-linear Schrödinger eqn: \begin{equation} \frac{\partial^2 u}{dx^2}-i\frac{\partial d...

Homework Statement Homework Equations ##\tau = rFsin(\theta)## ##\tau_{net} = I\alpha## ##F = -kx## ##kx = mg## The Attempt at a Solution I don't understand how the restoring force from the bending of the ruler behaves (so I have no idea how to apply torque here). I also don't understand how...

If friction is independent of area of contact, how do less inflated tires of a bicycle experience more resistance towards motion than the well inflated tires?

Can someone please share complex problems interrelated between Kinamatics, Force, Linear Momentum, Work and Energy along with final answers to cross-check.

Homework Statement the picture has all the information Homework Equations I am assuming we will be needing the viscosity equation, tao= mue(dv/dy) where v is velocity The Attempt at a Solution I do not know how to approach this exercise.

Homework Statement I have no idea what torque of a friction in a bearing is. I'm looking for good explanation. Homework EquationsThe Attempt at a Solution I understand what torque/friction/bearing is. But I have no idea how they come together when looking at the actual mechanical problem. Help!

Homework Statement A point like body with mass m1 is placed on top of a table, that can freely move on wheels with respect to the ground. There is a static friction coefficient of u=0.3 between the body and the table. If the body is subject to the gravitational acceleration g, what is the...

Hello, I'll try to get right to the point. Why and how does logarithmic dependence appear in statistical mechanics? I understand that somehow it is linked with probabilities, but I can not quite understand.

Homework Statement A perfectly elastic spring swings in a vertical plane as a simple pendulum with a mass m suspended at the bottom of the spring. The force constant for this spring is ##k## and the unstretched length is ##L##. The spring is carefully held in the horizontal position so that the...

Homework Statement A block of mass m is placed on a rough wedge inclined at an angle α to the horizontal, a distance d up the slope from the bottom of the wedge. The coefficient of kinetic friction between the block and wedge is given by µ_0x/d, where x is the distance down the slope from the...

Homework Statement A satellite is in a circular orbit (radius R) around a planet of mass M. To change the satellite's orbit the engines fire and its speed is suddenly doubled. The engines fire for a very short time. Determine the length of the semi-major axis of the new orbit. Homework...

Homework Statement A perfectly solid marble of radius R rolls without slipping at the bottom of a spherical bowl of a radius 6R. The marble rolls back and forth in the vertical plane executing simple harmonic motion close to the lowest point. How long does it take the marble to go down one side...