What is Mechanics: Definition and 999 Discussions

Mechanics (Greek: μηχανική) is the area of physics concerned with the motions of physical objects, more specifically the relationships among force, matter, and motion. Forces applied to objects result in displacements, or changes of an object's position relative to its environment.
This branch of physics has its origins in Ancient Greece with the writings of Aristotle and Archimedes (see History of classical mechanics and Timeline of classical mechanics). During the early modern period, scientists such as Galileo, Kepler, and Newton laid the foundation for what is now known as classical mechanics.
It is a branch of classical physics that deals with particles that are either at rest or are moving with velocities significantly less than the speed of light.
It can also be defined as a branch of science which deals with the motion of and forces on bodies not in the quantum realm. The field is today less widely understood in terms of quantum theory.

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  1. K

    Cantilevered and line-loaded steel beam

    I found the internal force Vxy 25 +6 =31kn. , bending moment Mmin -qb2/2 , M min- 14 kNm. delta =M/W I can't find Mmax and tau= V/As. So I need help to find Mmax and As wall area, how to find.
  2. lambdadandbda

    Zwienbach mastering quantum mechanics exercise 6.2 (time independence of a stationary state)

    I can write $$\psi(x,t_0) =\frac{1}{\sqrt{2}}(e^{\frac{-iE_1}{\hbar}t_0}\psi_1(x) +e^{\frac{-iE_2}{\hbar}t_0}\psi_2(x))$$ for the second coefficient to be -1 i need ## -1=e^{-i\pi}=e^{\frac{-iE_2}{\hbar}t_0} ## so ##t_0=\frac{\pi\hbar}{E_2}## and the above equation becomes $$\psi(x,t_0)...
  3. G

    Finding slip-off angle for mass off of sphere?

    [Rewriting this as per the suggestions. Thanks once again.] I won't be using the Lagrangian because it was never explicitly stated that I have to so I'll just use conservation of energy. $$ T = \frac{1}{2}mv^2 = \frac{1}{2}m(R\dot{\theta})^2 = \frac{1}{2}mR^2\dot{\theta}^2 $$ $$ V = mgy =...
  4. Frabjous

    Quantum Constructing Quantum Mechanics by Duncan

    Anyone read these books and care to share their thoughts? https://www.amazon.com/Constructing-Quantum-Mechanics-Scaffold-1900-1923/dp/0198845472/?tag=pfamazon01-20 https://www.amazon.com/Constructing-Quantum-Mechanics-Arch-1923-1927/dp/0198883900/?tag=pfamazon01-20
  5. T

    Recommendation for a book on Hamiltonian Mechanics

    Homework Statement: Practical examples of Hamiltonian Mechanics sought Relevant Equations: Hamilton Jacobi Equations, MTW Hi, I'm currently a bit stuck on Box 24.2 in MTW. I really need to get a better understanding of Hamiltonian Mechanics to be able to work my way through this and I...
  6. Hennessy

    I Calculus Question within Lagrangian mechanics

    Hi all currently got a lagrangian function which i've found to be : \begin{equation}\mathcal{L}=\frac{1}{2}m(\dot{x}^2+\dot{y}^2+4x^2\dot{x}^2+4y^2\dot{y}^2+8xy\dot{x}\dot{y})- mg(x^2+y^2) \end{equation} Let us first calculate $$(\frac{\partial L}{\partial \dot{x}})$$ which leads us to...
  7. R

    Final velocity of the barbell dropped after a dead lift

    Eddie Hall is the current world record holder in the deadlift, a powerlifting maneuver in which a weighted barbell is lifted from the ground to waist height, then dropped. The figure below shows a side view of the initial and final positions of the deadlift. A side view of the initial position...
  8. kuruman

    Insights How to Solve a Multi-Atwood Machine Assembly

    Continue reading...
  9. C

    Calculate how much weight the crane could lift

    I think the first part is F = mxa? But given the jib is resting on a turntable at a certain distance, does that mean the longer and shorted ends experience different loads? Especially when the shorter end has a 16T counterweight? The second part, I have no idea how to calculate this nor the...
  10. GLD223

    Generalized coordinates and the Lagrangian

    So I think the mass can only move in two "coordinates" the axis of which the mass is connected to ##k_1## and the axis connecting it to ##k_2##. Therefore, the D.O.F is 2. I don't understand what it the meaning of "variables of integration" What does it mean? Apart from that, I attempted to...
  11. D

    I Why L=L(v^2) in inertial reference system?

    Why he said that beacause space's propertiy is the same in both direction, so L=L(v^2), or do I misunderstand him incorrectly? btw this conclusion appears in somewhere like page 5 and its about Galilean principle of relativity.
  12. TheePhysicsStudent

    Need help on some mechanics questions from a text book

    These are the questions I am failing to comprehend despite their very basic nature This is the wonderful support from the book explaining how to get the answer ! (It just gives you the answer no working out which is annoying) I
  13. B

    I Is it possible to create linear acceleration using nothing but different moments of inertia beteen a wheel and axle?

    The Twisted Metal video game series includes a character aptly named Axel, whose vehicle is just himself strapped to a pair of tractor wheels. This is the guy: Most of my friends assume that in real life, he probably wouldn't be able to drive anywhere unless his feet were incredibly heavy, so...
  14. H

    Misc. Attach plates (my design) to the stator core of the machine

    I am working on an electrical engineering project. However, I have come across a specific mechanical engineering problem. I have attached an image to describe what I want to do. I have primarily a stator core (made out of electrical steel laminated sheets) named part number "1". I have a...
  15. tellmesomething

    Understanding Stress and Strain: The Relationship Between Two Variables

    I was going through the stress-strain curve and I realized that strain is taken as the independent variable and stress as the dependent variable. In reality is this true or is it the other way around?I saw a lot of answers on Quora that say that strain is the cause and stress is the effect. But...
  16. Argonaut

    Spring Problem Involving Variables and Constants Only

    Here is my attempt at the solution: a) The apparatus may only experience acceleration ##a > g## while in contact with the spring. Since the spring exerts the greatest force when it is the most compressed, the apparatus will undergo the greatest acceleration at that point. So Newton's second...
  17. L

    Confused about resolving Tension and Weight

    Calculations with 1: T1sintheta + T2sintheta = W T1costheta = T2costheta Calculations with 2: Wsintheta = T1 Wcostheta = T2 These are not equivalent. Can someone point out the flaw in my logic? Edit: System is in equilibrium!
  18. D

    Conservative forces in circular motion?

    TL;DR Summary: The rigid object move around the circle with constant force how it possible the force
  19. T

    From South Warrandyte Victoria Australia

    No Idea what I am expected to disclose here????
  20. areverseay

    Classical mech. - inelastic collision

    vA = 3u/4 and vB = u/4, and 1/8 KE is lost. I can't get to these answers however: for the first part, I got to u = vA + 3vB using conservation of momentum, and the fact that particle B is at an angle, hence I would think its momentum should be 10mvBsin(arcsin(3/5)). Doing the same for A with...
  21. W

    Classical Finding the Right Physics Books for College: A Guide for Students

    Hi,I m studying for college and I need to receive some info from you guys. Which books should I use to study mechanics,thermodynamics,electricity and magnetism? I have no idea what books I should study because my own physics teacher has some pdfs in her USB and I can t borrow the USB because...
  22. K

    I Acceleration in Newton's second law

    Hi, I was looking over one of the sample examples in Halliday and Resnick, the one about the scale in the elevator. There is something that bugs me about it, and I'd like to know if you agree. The example has to do with finding the reading of a scale that is measuring someone's weight in a...
  23. H

    Springs: Can they be used to conserve energy?

    Through mechanics, potential energy is released by the controlled falling of a suspended mass. At an idling condition, a one tonne mass is allowed to slowly fall. The pushing force of that mass is used to maintain a set rpm of a flywheel. The flywheel shaft drives an electric generator. At a...
  24. Z

    Apostol question about the differential equations of a falling object

    Here is my solution to this problem. Unfortunately, I can't check it because it is not contained in the solution manual. $$\frac{dv}{dt}=\frac{dv}{ds}\frac{ds}{dt}=v\frac{dv}{ds}$$ $$\frac{ds}{dv}=\frac{v}{v'}=\frac{v}{ge^{-kt/m}}$$ $$=\frac{\frac{m}{k}v}{\frac{gm}{k}e^{-kt/m}}$$...
  25. Kennard Callender

    Kennard Callender, independent scientist

    Hi, my name is Kennard Callender. I am an independent scientist from Panama working on the foundations of quantum mechanics and relativity. I look forward to meeting people who desire to understand nature at its most fundamental level and who can help me polish my work.
  26. C

    I'm searching for a theme for my matura project

    Hello I'd like to write my matura project on a topic of physics. But I can't really find a topic. I think I'd like to do something in the field of mechanics with reference to everyday life. The project requires an input of myself in this work, that means, i have to do something empirical and...
  27. P

    I PIGA: Pendulous Integrating Gyroscopic Accelerometer

    Wiki describes the PIGA, https://en.wikipedia.org/wiki/PIGA_accelerometer. I want to see if I have a basic intuitive understanding of how it works. https://en.wikipedia.org/wiki/PIGA_accelerometer#/media/File:PIGA_accelerometer_1.png Lets imagine that the device, as shown, is at rest on the...
  28. deuteron

    Missing Algebraic Step in Three-Body Newtonian Problem

    TL;DR Summary: I am missing an algebraic step in the below described three-body problem, any help is much appreciated Consider the following setup where the distance between the masses are ##d##, and they exert gravitational force on each other. We want to find the angular velocity of the...
  29. jjson775

    I Don’t understand the general form of the Sinusoidal Wave Equation

    I am a retired engineer, 81 years old, self studying modern physics using Young and Freedman University Physics. I am familiar with the wave equation y(x,t) = A cos (kx - wt) where A = amplitude, k = wave number and w (omega) = angular frequency. in the chapter introducing quantum mechanics...
  30. alalalash_kachok

    Part of bike wheel is cut out, find period of oscillations

    Assume the part of wheel with angle ##\phi## not is cut out, but is located next to cut out part. Turn this from right to left. Then wheel's center of mass will be higher by $$R\phi \sin(\alpha/2)$$. It allows to express potential energy. But I don't know how I can express kinetic energy in this...
  31. alalalash_kachok

    Oscillations of load with spring after rod is suddenly stopped

    I understand that after stopping of rotating I should consider second Newton's law: m d^2r/dt^2 = k(r-r_0) And using the law of energy conservation I can propose that energy of circular motion I (\omega)^2/2, where I = mr^2 - moment of intertia will be converted into spring's oscillation. But...
  32. A

    I need opinions on a Projectile Motion problem that I made up

    Recently I started making physics problems and I made one that I really like, but I would like some feedback from other people (how difficult it is, how enjoyable it is to solve this problem, what I could improve about it, etc). Here is the problem: A cannon is fixed at height H relative to the...
  33. J

    Calculate the bouyancy of two spheres joined by a rope submerged in seawater

    m * g = mAl * g V * ρ * g = VAl * ρAl * g V * ρ * g = V * ρAl * g ρ = ρAl this does not work at all, because the upper ball must have a density smaller than that of seawater 1200kg/m3 or not?
  34. L

    I Angular Momentum problem v2 (mass moving inward or outward)

    Hello, simplified the Angular momentum problem that comes up when i try to solve a mass moving inward or outwards and it does not conserver the angular momentum properly. I have tried this is many software by now, or by someone else and we all have found that there is no angular momentum...
  35. Joorge

    I Making a "Planetary Gear Set" using a 3D printer and PLA material

    I want to create a set of planetary gears using a 3D printer and PLA material. I'm designing them with the help of Autodesk Inventor 2020 since my knowledge in this area is quite limited. The gear set consists of a ring gear, a sun gear, and 2 planet gears. The sun and the ring gear rotate in...
  36. N

    Open problems

    Let's try to get into the looking glass of quantum mechanics together.
  37. niko_niko

    Confusion on mechanics problem involving cart, blocks, and pulley

    [Mentor Note -- Two threads on the same by the OP have been merged into one] I'm having trouble understanding the solution my professor gave me, in particular, the accelerations of m_2 and m_1. When my professor solved for the acceleration of m_2, he used a as the acceleration but when I look...
  38. O

    Modifying Euler-Lagrange equation to multivariable function

    I'm confused on how to derive the multidimensional generalization for a multivariable function. Everything makes sense here except the line, $$ \frac{\delta S}{\delta \psi} = \frac{\partial L}{\partial \psi} - \frac{d}{dx} \frac{\partial L}{\partial(\frac{\partial \psi}{\partial x})} -...
  39. N

    Other Which Springer books to buy? (QM, GR and statistical mechanics)

    Hello, Springer books are on sale this week so I wanted to buy some textbooks to support my studies and (eventual) future career. I'm an undergrad (in europe) and my courses next year will be QM, GR and statistical mechanics, so I was looking for books about these topics, but any suggestion on...
  40. P

    I Quantum Mechanics as a Probabilistic forecast of reality

    Is Quantum Mechanics a Probabilistic Forecast of nature?Someone I know told me their interpretation of QM is that QM only a probabilistic forecast of systems like electrons around atoms. I would like someone to analyse this interpretation and say if its valid or not. According to this person we...
  41. C

    Comparing two dams (fluid mechanics question)

    For this problem, The solution is, However, I though dams were built to withstand the average force exerted by the water. Therefore, from ##PA = F## a larger width dam would have less force exerted on it due to the greater area so would not have to be as thick (less mass, and thus inertia)...
  42. Daniel Guh

    AP Physics C Mechanics: Linear Momentum for Colliding Billiard Balls

    I'm guessing this question can be solved using the law of conservation of momentum Vi = 5 m/s (5 m/s) M = (4.33 m/s) cos30 M + V sinθ M I don't know what to do after this... I'm also not sure if I use the sin and cos correctly.
  43. hachi44

    I Principles of Quantum Mechanics - Hans C. Ohanian - 0137127952

    Hi. I looked everywhere for a specific book but I cannot find any pdf copy of it. The book specifics are below: Publication Name: Principles of Quantum Mechanics Author: Hans C. Ohanian Publisher: Benjamin Cummings Publishing Company ISBN-10: 0137127952 ISBN-13L 9780137127955 I would...
  44. Argonaut

    Maximizing Range/Time in Air of an Airplane: Solving with Calculus

    Is my solution correct? (I only have answers to odd-numbered exercises.) Is it a good solution or have I overcomplicated things? (a) The forward force provided by the engine balances the air resistance force, so ##F_{engine}=F_{air} = \alpha v^2 + \beta /v{^2}##. Let ##W_{engine}## be the...
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