Mechanics Definition and 999 Threads

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. V

    Books that teach classical mechanics through a discourse method

    Books that teaches classical mechanics through a discourse method ie asking interesting questions and answering them maybe a similar one to Understanding Basic Chemistry Through Problem Solving: The Learner's Approach Book by Jeanne Tan and Kim Seng Chan. Not exactly asking numerical questions...
  2. M

    I Blackbody radiation in quantum mechanics

    Hello! If I place a particle with more energy levels (of the order of kT) in a well defined state, in a thermal bath at temperature T, how will the blackbody radiation affect the internal state of the particle i.e. will the distribution be classical or QM? Basically, if I prepare that particle...
  3. D

    I Discussion about quantum mechanics and spacetime

    Robert Lawrence Kuhn: It seems that special relativity suggests time is like gravity and electromagnetism, not built into the absolute fabric of reality like logic and causation. David J Gross: Yes, time is dynamical. The phenomena are dynamical and are labeled by what we call time. Including...
  4. L

    I Help with Goldstein Classical Mechanics Exercise 1.7

    I'm trying to solve the Goldstein classical mechanics exercises 1.7. The problem is to prove: $$\frac{\partial \dot T}{\partial \dot q} - 2\frac{\partial T}{\partial q} = Q$$ Below is my progress, and I got stuck at one of the step. Now since we have langrange equation: $$\frac{d}{dt}...
  5. D

    B Observing Orbital Mechanics from the 2nd Focus of Earth's Orbit

    If a hypothetical spacecraft could keep station at the 2nd focus of Earth's orbit, what useful observations could be made? Each minute sees a new solar triangle Earth Sun Craft (ESC). Swept area remains constant, as should length SC, and length CE + ES. With the Sun as our point source...
  6. D

    I Morse Theory & Lagrangian Mechanics: Is There a Connection?

    I read somewhere that Morse originally applied his theory to the calculus of variations. I'm wondering, is this application useful in physics and mechanics, like maybe it sheds light on lagrangian mechanics? Does anyone know?
  7. RUTA

    Insights No Preferred Reference Frame: Quantum Mechanics Interpretations

    Continue reading...
  8. ayans2495

    Hiking the Appalachian Trail: A Beginner's Guide

  9. kimiko333

    Measuring the length of a moving Beam in two different directions

    v_g+v_e=15/t_1 v_g-v_e=10/t_2 v_g=s/(t_1-t_2) But there are too many unknowns. What am I missing?
  10. Pipsqueakalchemist

    I Is quantum mechanics imply nature is deterministic or probabilistic?

    So initially I thought quantum mechanics was deterministic in the equations but was probabilistic in measurement. I’m aware of bell’s inequality which rules out hidden variables unless you assume super determinism. But recently I’ve come across something called decoherence and some people have...
  11. O

    Courses Intermediate Mechanics Self-Review

    Good day, I performed relatively well(A-) in the first course of my sophomore mechanics class, but I don't feel as if I've sufficiently mastered the material to perform well in the 2nd course in the sequence, and of course, the principles of Lagrangian and Hamiltonian mechanics, simple harmonic...
  12. S

    MHB Momentum Change in Hockey Ball: Mass 0.2kg, Speed 8m/s to 5m/s

    A hockey ball of mass 0.2kg is hit so that its initial speed is 8 m/s. The ball travels in a horizontal straight line with acceleration given by a= - 0.5- kt where t is the time in seconds measured from when the ball was hit. After 2s the ball has traveled 41/3 m. It is then intercepted by a...
  13. U

    Studying Modern physics after quantum mechanics

    Hello everyone. I am studying physics as a self-study and would like advice on the next topics to study. So far I have been studying: -calculus, linear algebra and basic physics -classical mechanics (from Goldstein's textbook) -classical electrodynamics and special relativity (from Griffiths...
  14. U

    Koopman–von Neumann mechanics references

    Hello everyone, I am new here. I am studying physics as a self-taught student. I have been studying classical Lagrangian and Hamiltonian mechanics from Goldstein's book and have read that there is an additional formulation of classical mechanics in Hilbert spaces. Is it worth studying? Do you...
  15. yucheng

    Griffiths Quantum Mechanics Problem 1.18: Characteristic Size of System

    intermolecular distance means distance between particles. So, I imagine a sphere. $$\frac{4}{3} \pi d^3 = \frac{V}{N}$$ However, Griffitfhs pictures a box instead, where $$d^3 = \frac{V}{N}$$ And the difference between both models is a factor of ##(4\pi/3)^{2/5} \approx 1.8##, which is...
  16. S

    MHB Mechanics- connected particles

    Two particles A and B are attached to the ends of a light inextensible string, which passes over a smooth pulley. Particle A has mass 8 kg and particle B has mass 5kg. Both the particles are held 1.2m above the ground. The system is released from rest and the particles move vertically. a) when...
  17. S

    MHB Mechanics- connected particles

    Two particles A and B are attached to the ends of a light inextensible string, which passes over a smooth pulley. Particle A has mass 8 kg and particle B has mass 5kg. Both the particles are held 1.2m above the ground. The system is released from rest and the particles move vertically. a) when...
  18. R

    How Can I Analyze Particle Movement Given Potential Energy and Force Function?

    Knowing that ##F(x)=-\mathrm{d}V(x)/\mathrm{d}x##, I found that ##F(x)=-2.4x^3+1.35x^2+8x-3##. But it was the only thing I could find. How can I analyze what will be the type of movement with the information presented by the question statement?
  19. S

    MHB Mechanics- General motion in a straight line.

    It's the second question. Limiting equilibrium by a force of 5N means even friction is acting in the same direction. I don't understand how to calculate. Pls help
  20. S

    MHB Mechanics- General motion in a straight line.

    Iam not able to get the ans for q(a) which is 6.5 m/s I don't understand how to calculate (b)
  21. S

    MHB Mechanics- General motion in a straight line.

    A woman on a sledge moves in a straight line across horizontal ice. Her initial velocity is 2 m/s. Throughout the journey her acceleration is given by a= -0.01t m/s^2, where t is the time from the start in seconds. Find the distance that she travels before coming to rest. Iam getting the ans...
  22. S

    MHB Mechanics- General motion in a straight line.

    A goods train starts from rest at point A and moves along a straight track. The train moves with acceleration a m/s^2 at time t s, given by a=0.1t^2(6-t) for 0<t<6. It then moves at constant velocity for 6<t<156 before decelerating uniformly to stop at point B at t=165. Calculate the distance...
  23. S

    MHB Mechanics- General motion in a straight line.

    A particle starts at the origin and moves along the X- axis. The acceleration of the particle in the direction of the positive x-axis is a= 6t-c for some constant c. The particle is initially stationary and it is stationary again when it is at the point with x coordinate = -4. Find the value of...
  24. S

    MHB Mechanics- general motion in a straight line.

    I don't understand q(e) . Am I not supposed to calculate the distance between the interval 0 to 2? The textbook ans only shows the interval between 0 and 22. Should I calculate the distance taming only the second equation of velocity?
  25. S

    MHB Mechanics- general motion in a straight line.

    A particle moves in a straight line. The velocity of the particle, v m/s, at time t s is given by v= -t^3+9t m/s for 0<t<5 a) Find the displacement of the particle from its original position, when t=5s I got the ans for this by integration and limits 5 and 0 =- 43.8 b) work out the distance...
  26. S

    MHB Mechanics- general motion in a straight line.

    I calculated q(a)=1s q(b)=7cm I don't understand q(c)
  27. S

    MHB Mechanics- general motion in a straight line.

    S for 0 to 2s = 20m From 2s to 2.5s, I integrated v with limits 2.5 and 2 and got s=8.875m So total distance would be 28.9m but the textbook ans is 29.9m. Iam not able to get 29.9 m
  28. sophiatev

    Symmetries in Lagrangian Mechanics

    In Classical Mechanics by Kibble and Berkshire, in chapter 12.4 which focuses on symmetries and conservation laws (starting on page 291 here), the authors introduce the concept of a generator function G, where the transformation generated by G is given by (equation 12.29 on page 292 in the text)...
  29. S

    MHB Mechanics- general motion in a straight line

    I don't understand how to find the distance that robot travels in 10s.
  30. S

    MHB Mechanics- general motion in a straight line

    I don't know how to solve this
  31. S

    MHB Mechanics- general motion in a straight line

    I don't know how to calculate this. Pls help
  32. P

    Lagrangian mechanics - rotating rod

    Hello, It might sound silly, but when I try to calculate the kinetic energy of a rotating rod to form the Langrangian (and in general), why it has both translational and rotational kinetic energy? Is it because when I consider the moment of Inertia about the centre I need to include the...
  33. R

    Classical Looking for the absolute best fluid mechanics book available

    Dear physics forum dwellers, Currently on search for an advanced fluid mechanics book that covers all the nitty gritty details. Not looking for general introduction books like Munson, Rothmayer, ... or Cengel that are used in bachelor physics classes or engineering classes. Even after skimming...
  34. S

    MHB Mechanics- connected particles

    I have no clue how to do this. Pls help
  35. J

    Foundations Klein's Encyclopedia: Is an English Translation Possible?

    https://en.wikipedia.org/wiki/Klein%27s_Encyclopedia_of_Mathematical_Sciences Originals are in German or French, the Japanese version cut all the historical content :( Do you think that some day we will see this published in English? Size is big, 20k pages, but it cannot be more interesting I...
  36. S

    MHB Mechanics- connected particles

    I calculated a=8m/s^2. I don't understand how to calculate the total time.
  37. S

    MHB Mechanics- connected particles

    I got the speed of p when q reaches the pulleys = 1m/s, a= 2m/s^2 Iam getting time = 0.8s for q(b)
  38. S

    MHB Mechanics- connected particles

    Friction= 1/(sqroot12)×80 cos 30= 20N I get two equations T-20=8a and 120-T=12a a=5m/s^2 I don't know how to calculate the time. Also with this value of acceleration tension value is wrong and the textbook ans is 84N
  39. S

    MHB Mechanics- connected particles

    A passenger lift had mass 500 kg. The breaking tension of the cable is 12000N. The max acceleration of the lift is 0.75 m/s^2 a) if the lift travels at its max acceleration, calculate the max mass of the passengers: 1)when the lift is accelerating upwards 2) when the lift is accelerating...
  40. S

    MHB Mechanics- connected particles

    A box of mass 20 kg sits on the floor of a lift. A second box of mass 10kg sits on top of the first box and a third box of mass 5kg sits on top of the second box. When the tension in the lift cable is 4260N, the lift is accelerating upwards at 0.5m/s^2. a) work out the mass of the lift. b) work...
  41. S

    MHB Mechanics- connected particles

    A crate of mass 20 kg is put into a lift. The mass of the lift is 300kg. Find the tension in the lift cable. a) when the lift accelerates upwards at 0.3m/s^2 b) when the lift travels at constant speed c) when the lift accelerates downwards at 0.3m/s^2 For (a) is it T- W-w= ( M+m) a Where T is...
  42. S

    MHB Mechanics- connected particles

    Two smooth pulleys are 8m apart at the same horizontal level. A light inextensible rope passes over the pulleys and a box of mass 5kg hangs at each end of the rope. A third box of mass m kg is attached to the midpoint of the rope and hangs between the pulleys so that all the three boxes are at...
  43. J

    A Do we really need the Hilbert space for Quantum Mechanics?

    Let's play this game, let's assume the infinite Hilbert Space, the operators and all the modern machinery introduced by Von Neuman were not allowed. How would be the formalism? Thanks
  44. S

    MHB Mechanics- connected particles

    A bucket of mass 3kg rests on scaffolding at the top of a building. The scaffolding is 22.5m above the ground. The bucket is attached to a rope that passes over a smooth pulley. At the other end of the rope there is another bucket of mass 3kg, which initially rests on the ground. The bucket at...
  45. S

    MHB Mechanics- connected particles

    A car tows a caravan down a hill. The slope of the hill makes an angle theta with the horizontal, where sin theta = 0.05. The force from the car's engine is a braking force ( a negative driving force). The car has mass 1800 kg and the caravan has mass 600kg. The resistance on the car is 20N and...
  46. S

    MHB Mechanics- connected particles

    A horizontal bar of mass 1kg hangs from a pair of parallel vertical rods of negligible mass, attached to either end of the bar. A third vertical rod is connected to the middle of the bar and a 4kg mass hangs from this below the rod. Work out the tension in each of the rods. I got the tension in...
  47. S

    MHB Mechanics- connected particles

    A car of mass 2000kg pulls a caravan of mass 1200kg along a straight horizontal road. The resistance on the car is 20N and the resistance on the caravan is 80N. The max possible driving force from the car's engine is 1900N. The tow-bar will break if the tension exceeds 680N. a) Find the max...
  48. S

    MHB Solving Mechanics Problem: Friction, 2 Boys, Toy Acceleration

    Two boys are arguing over who gets to play with a toy. The toy has mass 3kg and is at rest on rough horizontal ground with coefficient of friction 0.3. The older boy pulls with a force of 26N at an angle of 39 degree above the horizontal. The younger boy pulls in the opposite direction with a...
  49. S

    MHB Solving Mechanics Friction Problem: How to Calculate Contact Force

    It's the 10th question. Iam getting the ans for R=90cos34= 74.6 and F=-30.3N, so I get total contact force by using the formula c= sqroot(f^2+R^2)= 80.52N The ans in the textbook is 92.2N. Iam not getting the right ans for coefficient of friction also which is 0.393
  50. S

    MHB Find Coefficient of Friction for Toy Car Rolling Down Slope

    A toy car of mass 80g rolls from rest 80cm down a rough slope at an angle of 16 degree to the horizontal. When it hits a rubber barrier at the bottom of the slope it bounces back up the slope with its speed halved and reaches a height of 10 cm. Find the coefficient of friction between the car...
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