Static equilibrium Definition and 360 Threads

In classical mechanics, a particle is in mechanical equilibrium if the net force on that particle is zero. By extension, a physical system made up of many parts is in mechanical equilibrium if the net force on each of its individual parts is zero.In addition to defining mechanical equilibrium in terms of force, there are many alternative definitions for mechanical equilibrium which are all mathematically equivalent. In terms of momentum, a system is in equilibrium if the momentum of its parts is all constant. In terms of velocity, the system is in equilibrium if velocity is constant. In a rotational mechanical equilibrium the angular momentum of the object is conserved and the net torque is zero. More generally in conservative systems, equilibrium is established at a point in configuration space where the gradient of the potential energy with respect to the generalized coordinates is zero.
If a particle in equilibrium has zero velocity, that particle is in static equilibrium. Since all particles in equilibrium have constant velocity, it is always possible to find an inertial reference frame in which the particle is stationary with respect to the frame.

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  1. Zulliz

    Engineering Help with a statics problem finding free members and two force members

    Heres my first attempt at finding the forces at D: https://i.sstatic.net/CRv5Ikrk.png
  2. Y

    Engineering Statics problem (Simple first year): Calculate the internal forces for this structure

    I need to calculate the internal forces M3, V3, and N3 for a specific section of a structural system. The known reaction forces are: R_AH = -5.7 kN R_AV = 0.7425 kN R_CV = 5.02 kN Two different sections have been analyzed: one on the left side of the cut (my choice) and one on the right side...
  3. kirito

    I How is the net force on the system equal to 0 initially?

    I understand that in the initial condition both the net torque and net force are zero since the system is in a static state , the net torque remains zero as the mass down is being pulled , the two blocks get pulled towards the axis of rotation by a radial force but I am wondering what is...
  4. E

    What is the angle of static equilibrium for a ladder on ice?

    tried equating torques around the pivots of the ladder and equating them to zero but I'm not getting anywhere with that.
  5. YehiaMedhat

    Engineering Is My Free Body Diagram for a Frame Accurate?

    can you check if I sketched it correctly? And please if you know any good resources refrence it.
  6. tracker890 Source h

    Why Is Taking Moments at Point A' Incorrect in Rotational Balance Problems?

    Please help me to understand why it is wrong to take moment for point ## A’ ## , because I think static equilibrium should be static equilibrium for any point in space. Method 1： $$ \sum{M_A=0:} $$ $$ F\cdot R=\left( F_p \right) _x\cdot \left( R-y_p \right) +\left( F_p \right) _y\left( x_p...
  7. H

    Sign hanging from massless beam attached to hinge supported by string

    Attempted creating equations for zeros of torque and components of forces in x and y as seen in picture. Got lost with having only variables and the d & 2L for the length of the beam. Not sure how to do the question with two points of contact between the beam and the sign. Is the center center...
  8. S

    Tetrahedron with 3 points fixed, and force applied to 4th

    My approach to this problem is to recognize that the tetrahedron being still means that net torque is zero and net force is zero. Fd is given Fa + Fb + Fc = -Fd Fa X a + Fb X b + Fc X c = <0,0,0> This can be split up into a series of 6 equations, 2 for each component. However, this is where I...
  9. bbsgirl10

    Static Equilibrium of a Rod attached to a Pivot

  10. L

    Engineering Hand tool boundary conditions - Forces determination

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  11. NovatoOfPhysica

    Virtual Work and Static Equilibrium

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  12. Pawn

    Can someone help me find which object is in static equilibrium?

  13. S

    Body forces in static equilibrium (FEM issue)

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  14. L

    Is there any friction in this case?

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  15. C

    Calculate dimensions of floating laptop stand

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  16. hedera

    Statics problem, suport reactions and pins, IDK where to go

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  17. S

    Why Does Torque Equilibrium Not Solve for Fcy in Static Equilibrium Problems?

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  18. D

    Conceptual Problem - Static Equilibrium

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  19. R

    Trouble with Static Equilibrium

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  20. J

    Static equilibrium: mass on beam

    A diagram of the physical situation is below: Choosing the positive ##y## direction to be upwards and the positive direction of rotation to be counterclockwise, Newton's linear second law gives: $$-m_D g + F_L + F_R = 0$$ where ##F_L## is the magnitude of the force exerted on the bar by the...
  21. Jose18

    Static equilibrium, forces and toques

  22. archaic

    Static equilibrium problem: Finding tension

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  23. archaic

    Static equilibrium: Placing a fulcrum

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  24. archaic

    Static equilibrium and a diving board

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  25. S

    Static Equilibrium Problem (concept question)

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  26. J

    Motion of 2 masses connected by a rod to a pendulum

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  27. benny1993

    Understanding Static Equilibrium and Beam Forces: A Troubleshooting Guide

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  28. penroseandpaper

    How Do You Calculate Torques for a Ladder in Static Equilibrium?

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  29. A

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  30. M

    Engineering Calculate Static Equilibrium: SOH/CAH/TOA?

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  31. greenrichy

    Find the stretch of a steel wire in a static equilibrium problem.

    If I can determine the weight of that heavy object placed on the plank, I will be able to determine the stretch of that wire. But, when using the second condition for static equilibrium (torques of the system equal to 0), I always end up with two unknowns, no matter what point of rotation I...
  32. EEristavi

    Rotational Motion / Static Equilibrium - Mechanics

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  33. N

    Static equilibrium force decomposition problem

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  34. Lone Wolf

    Static equilibrium -- interpretation of forces

    I solved this question correctly, however I have a question regarding how I should work with the weight of the firefighter climbing the ladder. When drawing the force diagram for this problem, I should only include forces acting on the ladder, right? Which means I would represent the normal...
  35. E

    Show that a tilted free liquid surface undergoes shear stress

    i really can't understand the answer of this question, is the question 1.3 in fluid mechanics by Frank ,M White For the triangular element in Fig P1.3, show that a tilted free liquid surface, in contact with an atmosphere at pressure pa, must undergo shear stress and hence begin to flow. i...
  36. M

    Asymmetrical Static Equilibrium

    a) Answer that I found: 56.31 degrees b) Answer that I found: 121.71 Kg For b) not sure if I need to add the 20 N and 5 N to the total of the cargo mass.
  37. Susie

    Tension Force Problem: Solving for T1 with x and y components using trigonometry

    I know I have to find the x and y components of T1 using 400cos(55) and 400sin(55) and I know that the x-component of T1 will = the x-component of T2 but opposite sign to give 0. But idk how to get there and what do to for the y-component. I think I found the weight, I think it’s 32.42g but I’m...
  38. mmest

    Magnetic Field required to hold a loop in static equilibrium

    Homework Statement There is a square loop with mass of 4.0 kg and side length 4.5 m that is tilted upwards from the ground at a 25 degree angle with one side resting on the surface. The loop is a conductor that has 25 A of current going through it. The question asks to find the strength a...
  39. S

    Static equilibrium -- A picture hanging on a wall

    Homework Statement https://imgur.com/v13K6sE a uniform rod of mass m is placed as shown, with one of its end resting on a smooth wall while 1/4 of the rod's length is sticking out of a rough table. Find the net force the table exert on the rod at the corner. Homework Equations i drew the free...
  40. Arman777

    Spring static equilibrium Problem

    Homework Statement a) If the distances ##s_1## and ##s_2## are the amounts the springs are streched while in static equilibirum, Write down the static equilibirum equations. b) When the system is distrubed from its equilibirum state, both mases move vertically. Let ##y_1(t)## and ##y_2(t)##...
  41. G

    Question about Normal Force and Torque

    Homework Statement A block of uniform density experiences a force F to the right, applied 5/3 m from the bottom of the block. The block is 2 m high and 1 m wide. Take the pivot point to be the point at the bottom right of the block. Find the value of the force that is just able to tip the box...
  42. S

    Static equilibrium: Find the tension in a support cable

    Homework Statement Homework Equations Σtorque = 0 Σfx=0 Σfy=0 torque= F r sinθ (θ is the angle between the r and the F)The Attempt at a Solution OKay, now i know how to solve this, but it's like i asked myself, how to know if this is a question that i am supposed to use Σfx=0 and Σfy=0...
  43. F

    Statics and equilibrium - asking for some guidance

    Hi, I'm not used to communicate physics in English, so my language may be a bit off. This task is fairly simplistic. It's a figure which is held up in points A and B (both having an x and y force exerted on them), and the figure has a joint C. It is depicted in attached files. The answers...
  44. S

    B Maximum Overhang in Static Equilibrium

    Hi, i am trying to trying to solve this question as this question is slightly different from the usual type of overhanging question. Please advice on the approach. Thank you I have to find the maximum overhang possible, l, before the whole blocks falls apart
  45. I

    Force Calculation -- Hydraulic cylinder and a rotating arm

    Hi There, Long time reader, first time poster.. I hope someone out there can help me. I'm designing an add-on to an existing piece of equipment and I'm unsure of how to calculate the resultant force output from a hydraulic cylinder. On a straight push, the chosen hydraulic cylinder has an...
  46. Zack K

    Weight of an object in static equilibrium

    Homework Statement An object is suspended on a frictionless slope inclined plane by a rope parallel to the incline. If the angle of the incline is 25° and the tension on the rope is 5000 N, what is the weight of the object Homework Equations ∑F=0 The Attempt at a Solution So in my eyes, you...
  47. A

    Quick Question about Torque and Tension

    Homework Statement A meter stick with a mass of 260 g is supported horizontally by two vertical strings, one at the 0-cm mark and the other at the 90-cm mark A) What is the tension in the string at 0 cm B) What is the tension in the string at 90 cm C) The string at the 90-cm mark is cut. What...
  48. Zack K

    Mass of a picture in static equilibrium

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  49. Emanuel0406

    How Can I Solve This Static Equilibrium Problem?

    Hello! I was wondering if anyone could give me a hand with the following problem. I am stuck and I don't know how to solve it. You can see attached the problem and my work so far. Thank you very much for your help.
  50. Emanuel0406

    Solve Static Equilibrium Problem: Get Help Now

    1. The problem statement, all variabHello. I uploaded a picture with the problem that concerns me. As you can see from my work so far...I have tried to solve the problem but I'm stuck. I have tried a few times and I'm starting to question myself if the problem is correct or not. Please give me a...
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