Mechanics Definition and 999 Threads

  1. S

    Classical Supplement to Classical Mechanics by Goldstein

    Are there any lecture notes that closely follow Classical Mechanics by Goldstein? I am asking this since I am seeing some comments in this forum that it contains some conceptual errors, e.g. nonholonomic constraints. If there is a book that "closely" follows Goldstein, it will be good too.
  2. AlonZ

    Mechanics- Conservation of energy

    My, supposedly rational thought is that if the pendulum will drop from a height higher than the top of the loop's height, by the law of conservation of energy, it'll have enough velocity to complete the loop. The teacher's final result shows a different approach. Am I right? Wrong? Thanks
  3. RemotePhysics

    Futher Mechanics: Circular Motion of a Car Going Around a Banked Turn

    Below is my working out. If you could have a look at my answers and see if they are correct and then advice me on how to improve my solutions for Parts I and II, and how to answer F and G with the given information. Thanks in advance! Parts aand b are diagrams so please refer to the attached...
  4. G

    Mechanics: Angular Velocity Vector Questions

    Answers are the following : (i) v=(2cost)i - (2sint)j -(1/2)k (ii)2.06m/s (iii)2m/s^2 horizontally towards the vertical axis, making an angle of pi/4 with both the I and j axes.
  5. core1985

    Which system of units is coherent for mechanics?

    So, should i write All of these as accodring to wiki pedia maxwell applied coherence concept to FPS, CGS, and SI is already coherent so answer will be All of these ?? Am i right or MKS because question is restricted to mechanics only ?
  6. P

    Tackling a Classical Mechanics Problem at Pisa University

    This problem is hard. It found it listed among problems discussed in a classical mechanics course for physicists at the university of Pisa and don't have a full solution. It's not 100% guaranteed that there's a nice close-form solution, but probably yes; and if not, there should be some trick to...
  7. D

    Equations of motion of a system with non holonomic constraints

    Hello, I have a system with 2 degrees of freedom with 2 non-holonomic constrains that can be expressed by:##A_1 dq_1 +Cdq_3 + Ddq_4 = 0## ##A_2 dq_1 + Bdq_2 = 0##Being ##q_1, q_2, q_3## and ##q_4## four generalized coordinates that can describe the movement of the system. And ##A_1, A_2, B...
  8. bob012345

    I Is Quantum Mechanics Infinitely More Complex than Classical Mechanics?

    Please critique this text. It came from a research article* I found but I'm only interested if the sentence is 100% accurate or not and not in the specifics of the article itself. Are they suggesting Hilbert space is always infinite? Thanks. Quantum mechanics is infinitely more complicated than...
  9. LuccaP4

    Hamiltonian mechanics: phase diagram

    The issue here is that I don't know how to operate the final equations in order to get the phase diagram. I suppose some things are held constant so I can get a known curve such as an ellipse. I attach the solved part, I don't know how to go on.
  10. A. Neumaier

    I Steven Weinberg on the interpretation of quantum mechanics

    I think Weinberg is quite clear about this: On p.87 of the second edition of his quantum mechanics book, he says, and on p.88: After having discussed decoherence, he says on p.92: For the instrumentalist approach (apparently your view of the matter), he states on p.92f this drawback: Then...
  11. S

    Quantum What are the best books for: 1.Mass 2.Energy and 3.Quantum Mechanics?

    What are the best theoretical books I can study for understanding the basic as well as advanced; mass, energy and quantum mechanics.
  12. L

    Dispersion relation statistical mechanics

    I know that this is the general case of the Einstein and Debye Model.
  13. G

    I How does Bohmian mechanics explain quantum bomb testing?

    Hi. In an Elitzur–Vaidman bomb tester, will the guiding wave be different in a situation with a live bomb compared to one with only a dud? And if yes, how does the bomb interact with the guiding wave? Because usually it is described as a pointlike device that only explodes when hit by the...
  14. LuccaP4

    Lagrangian mechanics: central-force-like problem

    I copy again the statement here: So, I think I solved parts a to c but I don't get part d. I couldn't even start it because I don't understand how to set the problem. I think it refers to some kind of motion like this one in the picture, so I'll have a maximum and a minimum r, and I can get...
  15. PGaccount

    I Partition function of quantum mechanics

    In quantum mechanics, we have the partition function Z[j] = e-W[j] = ∫ eiS+ jiOi. The propagator between two points 1 and 2 can be calculated as ## \frac{\delta}{\delta j_1}\frac{\delta}{\delta j_2} Z = \langle O_1 O_2 \rangle## The S in the path integral has been replaced by S → S + jiOi...
  16. J

    MHB Engineering Mechanics: airplane landing

    The landing speed of an airplane is 360 kph. When it touches down, it puts on its brakes and reverses its engines. The retardation in its speed is 0.2 times the square root of its speed. Determine the time elapsed in seconds from the point of touchdown until the plane comes to a complete stop.
  17. J

    MHB Engineering Mechanics: car speeding up

    A car starting from rest picks up at a uniform rate and passes three electric post in succession. The post are spaced 360 m apart along a straight rod. The car takes 10 seconds to travel from the first post to the 2nd post and tales 6 seconds to go from the 2nd post to the 3rd post. Determine...
  18. J

    MHB Engineering Mechanics: depth of crater

    The depth of the crater of the Taal volcano was calculated in the following manner: From a helicopter flying vertically upward at 6m/s. A small bomb was released at the instant the helicopter was 20m above the crater surface. The sound of explosion was heard 9sec later. If the speed of sound is...
  19. Lynch101

    I Understanding Bohmian Mechanics of Instrumentalists

    I recently read @Demystifier's paper entitled, Bohmian Mechanics for Instrumentalists and I found it quite interesting. There is a danger that I am guilty of a certain amount of confirmation bias, as I find that deterministic interpretations are more closely aligned to my own logical reasoning...
  20. AndreasC

    I Is Quantum Field Theory Redefining the Foundations of Quantum Mechanics?

    Hey, applied maths and physics student here. I started wondering recently what the meaning of measurement was in quantum mechanics, and I remembered that I had once heard of the bohmian interpretation which challenged the impression I had so far (which was that hidden variables had been...
  21. K

    Quantum High-level book on scattering in quantum mechanics

    I'm interested in a book which treats scattering in quantum mechanics aimed at the research-level. I'm particularly interested in a text which focuses on mathematical details such as the analytic structure of the S matrix, the relation between the S matrix and various green's/two-point...
  22. A

    Calculation Involving Thermodynamics, Gravitation and Fluid mechanics

    I figured out stokes law equation but I am unable to proceed further
  23. H

    Calculating Period of System with Masses, R & dX

    Here is the picture on the system. I have to find the period (T). The masses, R and dX is given. The systam at first is at rest, then at t = 0 we pull the plank to dX distance from its originial position. In the thread...
  24. Ahmed Mutaz

    Finding little g using an inclined plane

    The slope of the v^2 vs h graph is g
  25. Jarvis323

    I Modern Assesment of Grete Hermann's Philosophy on Quantum Mechanics

    As a quarantine hobby I've been learning about Grete Hermann and the early history of QM. I find her early philisophical contribution to be interesting, but I lack the background to put it into a modern context. A brief description can be found in the arxiv paper: Grete Hermann: An early...
  26. J

    I Changing spherical coordinates in a Lagrangian

    In order to compute de lagrangian in spherical coordinates, one usually writes the following expression for the kinetic energy: $$T = \dfrac{1}{2} m ( \dot{r}^2 + r^2 \dot{\theta}^2 + r^2 \sin^2 \theta \dot{\phi}^2 )\ ,$$ where ##\theta## is the colatitud or polar angle and ##\phi## is the...
  27. H

    Mechanics: Two masses on a pulley causing two cylinders to accelerate

    Hi! I need help with this problem. m1-2-3-4 and R are given. There is no slip in the system. I have to give F1-2-3-4 in respect of the masses and R. Here is what I managed to m1 is easy: m1*a = m1*g - T(tension of the rope) m2: m2*a = T - (?) <-- I have a problem with this. F1 and F3 is the...
  28. LCSphysicist

    What is the minimum mathematic requirement for learning Lagrangian and Hamiltonian mechanics?

    Homework Statement:: ... Relevant Equations:: . What is the minimum mathematic requirement to the Lagrangian and hamiltonian mechanics? Maybe calc 3 and linear algebra?
  29. A

    Rotational Mechanics -- A solid sphere is rolled on a rough surface

    I found out the time when rotation ceases to be 4 ##v_0## /5*mew*g, where mew=coefficent of friction of surface but I am unable to plot the graph post that time
  30. Mayhem

    Rotational Mechanics Question - A Rotating Bar

    This isn't really a proper homework question, but something I wondered about myself. To simplify things, we say that pivot point is in the origin of a Cartesian coordinate system, and the angles are constrained to the first quadrant. We see that the weight of the barbell is given as $$F =...
  31. FreeRoger

    Studying Mastering Classical Mechanics: Tips for Developing Your Own Ideas in Physics

    Hi- So I have been studying physics for a long time, and I love most parts of it, but I have a love-hate relationship with classical mechanics. Every time I read my textbook I can work my way through it and it makes sense to me, but one or two days later I forget all the formulas I have...
  32. yam1244

    Solving this exercise in mechanics -- Tipping over this rectangular object

    A body is placed on a surface with friction Force is applied to the right at the upper end of the body What is the condition that will cause the body to roll over?
  33. cemtu

    Quantum Mechanics Hydrogen Atom Expectation Value Problem

    I can not solve this problem: However, I have a similar problem with proper solution: Can you please guide me to solve my question? I am not being able to relate Y R (from first question) and U (from second question), and solve the question at the top above...
  34. cemtu

    Quantum Mechanics hydrogen atom eigenfunction problem

    This is a general property of eigenvectors of Hermitian operators. State functions are a particular class of vector, and it is easiest to work in the general formalism (I am hoping to show how ket notation makes qm easier, not just do standard bookwork at this level). Suppose O is a Hermitian...
  35. I

    Help please differentiating this equation from a mechanics textbook

    I tried doing it a few times and this is all I get: c(˙f1+˙f2)=a˙a2+a2˙a−3ca2+˙ha2+2ha+2˙af′2+2a˙f′2c(f1˙+f2˙)=aa˙2+a2a˙−3ca2+h˙a2+2ha+2a˙f2′+2af2′˙ Please let me know where I'm going wrong. Thanks
  36. cwill53

    Mechanics Question- Massive Rope in a Pulley System

    I understand how they might have got to these answers but I'm still kind of shaky on how the mass of the rope plays a role in the tension at point B, and how to mathematically represent the tension at any point along the rope; I know the tension varies because the rope has mass. If I was to...
  37. G

    How do I solve for the centroid of a function with a given range?

    Summary:: I'm solving an exercise. I have the following center of gravity problem: Having the function Y(x)=96,4*x(100-x) cm, where X is the horizontal axis and Y is the vertical axis, ranged between the interval (0, 93,7) cm. Determine: a) Area bounded by this function, axis X and the line...
  38. cwill53

    Solving the Mechanics Puzzle of Meshcherskii: Understanding Thrust and Drag

    "Collection of Problems of Mechanics" by Meshcherskii.I see how the answer could be arrived at because each successive drag increases the number of ropes that must be used, but what I don't understand is why the thrust and drag of the tug doesn't play a role in the number of ropes required.
  39. N

    Analyzing the Mechanics of a Wobble Plate in a Cranked Axle Mechanism

    In the following cross section, the static guide plate (light blue) is rigidly constrained, fixed to the body (not shown) of the mechanism. It serves as the mounting point for a cranked axle (dark blue) via a combination thrust and radial bearing (pink & yellow) that constrains it to a single...
  40. Achintya

    Sporting Goods for Outdoor Adventurers

    .
  41. S

    Fluid Mechanics: Fluid Transfer Between Two Reservoirs at Different Heights

    A reservoir supply tunnel transfers water from a high level storage reservoir via a 200mm diameter pipe to a lower intermediate reservoir. The total height difference between the free surfaces of each reservoir is 76 m. The pipe is 700 m long and the coefficient of friction, Cf is 0.009. The...
  42. A

    A Superluminal origin of Quantum Mechanics

    A relativistic origin of QM is proposed in https://iopscience.iop.org/article/10.1088/1367-2630/ab76f7 It is proposed that lorentz transformation that include superluminal observers (whether those observers exist or not) explain the indeterministic behavior of QM. Not only that, it also would...
  43. Rongeet Banerjee

    Work, Energy and Power for a Particle moving in a Potential Field

    But yet again my text says that option 4 is correct.
  44. Rongeet Banerjee

    Why does my textbook say the KE acquired by an object is m to the power zero?

    Initial velocity u=0 Let Final velocity be v Then, KE acquired by the object=1/2mv² So the answer must be option1 i.e. m¹ But my textbook says the answer is- m to the power zero.Please explain this discrepancy.
  45. S

    Mechanics Question -- The direction of the pseudo force

    I'm often got confused about why the direction of pseudo force is taken opposite to the direction of motion of the body. As specific, I have this question. In this, I didn't understood about why the direction of pseudo force is taken in right, in the diagram of solution provided to this...
  46. U

    I Quantum Mechanics Particle in a Box

    I need help .I did not A) E < V0 for T =? (passing coefficient ) B) E = V0 for T = ? C ) E > V0 for T =? A
  47. M

    Venturi Ejector Air Flow Mechanics

    Hi, I am trying to figure out the strength of the various type of airflow for my Venturi ejector device. Please refer to my diagram that illustrates scenario A or scenario B. The SAME amount of compressed air is injected for both scenario A and B. For simplicity, I have added to an electrical...
  48. L

    A Potential step at a Barrier in Quantum mechanics

    In quantum mechanics in books authors discuss only cases ##E<V_0## and ##E>V_0##, where ##E## is energy of the particle and ##V_0## is height of the barrier. Why not ##E=V_0##? In that case for ##x<0## \psi_1(x)=Ae^{ikx}+Be^{-ikx} and for ##x\geq 0## \psi_2(x)=Cx+D and then from...
  49. C

    Fluid mechanics problem: Hydrostatic forces acting on a gate

  50. G

    B Adjoint Operation in Shankar's "Principles of Quantum Mechanics

    In R Shankar text on “principles of quantum mechanics’ discussing the adjoint operation, 1.3.8 shows that a|V> => <V|a*. Then 1.3.9 then states that <aV| = <V|a*. Is this a typo error?
Back
Top