What is Static equilibrium: Definition and 358 Discussions

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. B

    Static equilibrium of diving board

    Homework Statement A uniform diving board of mass=27kg and length x=4.3m is supported by two beams. beam A at x=0m and beam B at x=1.1m. A 68kg diver stands at the other side of the board. A. Find force on support A. B. Find force on support B. Homework Equations Net force = 0 Net...
  2. J

    Static Equilibrium, new to this subject, help please?

    Homework Statement So I have looked at several ladder example problems, (the most basic for statics), but was given a problem by my professor that has me a little stumped. This is day 2 of learning for me and I am caught up, here's the problem: A 30.8 kg beam is attached to a wall with a...
  3. B

    Frictional Torque for Static Equilibrium of a Pulley

    Homework Statement A mass of 0.311kg is attached to one end of a string, and a mass of 0.625kg is handing off the other end. The string goes over a pulley which has friction in its axle. What is the magnitude of frictional torque required to maintain static equilibrium? Homework...
  4. L

    How Do You Calculate Tension and Hinge Forces in Static Equilibrium?

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  5. O

    Simple harmonic motion and static equilibrium

    Homework Statement In static equilibrium a spring is stretched 0.25 m by a hanging mass. If the system is initially moved up to the unstretched position and released with zero velocity, determine position of the mass (in m) after 4.2s. Take the equilibrium position to be zero and up the...
  6. T

    Determining static equilibrium this way?

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  7. M

    Static Equilibrium With Spring

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  8. T

    Static equilibrium of a window washer

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  9. M

    Static Equilibrium and reaction forces

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  10. R

    Help, static equilibrium solving for maximum angle of incline

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  11. K

    Solve Static Equilibrium Qs: 17.55kN & 17.45kN, 15.63kN & 16.37kN

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  12. I

    The bar is in static equilibrium W = 15N, Na = 11N

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  13. H

    How Is Tension Calculated in a Rope Held by Two People Leaning Back?

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  14. M

    Rigid Objects In Static Equilibrium: Mass on a Bar

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  15. N

    Static equilibrium thrust bearings

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  16. M

    How Much Force Must the Biceps Generate in an Isometric Exercise?

    Homework Statement During an isometric exercise for strengthening the biceps, an external force of 200 N is applied perpendicular to the forearm 0.3 meters from the center of rotation of the elbow joint. The elbow is flexed to 90 degrees and the forearm is supinated. The force produced by...
  17. Q

    Static Equilibrium of weighted door

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  18. C

    Static Equilibrium of mass and wire

    Homework Statement A 345 kg mass is supported on a wire attached to a 15 m long steel bar that is pivoted at a vertical wall and supported by a cable. The mass of the bar is 95 kg. (Take right and up to be positive.) http://img522.imageshack.us/img522/8374/1265alt.gif" (a) With the...
  19. C

    Static Equilibrium of hinge Question

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  20. M

    Need answered by tonight, Static Equilibrium

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  21. S

    Wheelbarrow in Static equilibrium

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  22. J

    Static Equilibrium: Solving Homework Problem

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  23. B

    Static equilibrium, diving board

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  24. B

    How Does a Pulley Find Its Equilibrium Position in a Static System?

    Homework Statement Consider the situation of the figure, where a string of negligible mass and length L is fixed at two points A and B, with B dislocated of A by a distance w(<L) and vertically dislocated by a distance h < sqrt(L^2-w^2) A mass is hung on the rope using a moving pulley of...
  25. F

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  26. C

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  27. C

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  28. K

    Laws of Motion with Static Equilibrium

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  29. Y

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  30. H

    Free Body Diagrams: Static Equilibrium

    Homework Statement Blocks A & B each have mass 5kg, and all contact surfaces are frictionless. Determine the force F needed to keep the blocks in static equilibrium, and the forces on all contact surfaces. Homework Equations I know I need to find where Fx= 0 and where Fy= 0. The Attempt...
  31. J

    Static Equilibrium. Man on Ladder

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  32. Wellesley

    Static Equilibrium of door and hinge

    Homework Statement A door made of a uniform piece of wood measures 1 m by 2 m and has a mass of 18 kg. The door is entirely supported by two hinges, one at the bottom corner and one at the top corner. Find the force (magnitude and direction) that the door exerts on each hinge. Assume that the...
  33. G

    Static Equilibrium of a beam and hinge

    Homework Statement A 90 N sign hangs on the end of a 55 N beam supported by a wire as shown. The beam is attached to the wall by a hinge. What are the horizontal and vertical componetns of the force on the hinge? Notes: the sign is 1.7 m from the wall the CG of the beam is located...
  34. E

    Static Equilibrium incorporating torque

    Homework Statement A 60 kg man hangs one meter from the end of an 8 m, 100 kg beam. A steel cable is attached to the end of the beam near the man, and the opposite end is supported by a frictionless pin (or a hinge). The system is originally at rest. The cable makes a 35 degree angle between...
  35. K

    Static equilibrium (conceptual)

    In order for an object to be in static equilibrium a)the net force in all directions must be zero b)the net torque must be zero c) the object's velocity must be zero d) a and b are correct e) all of the above 2. I know that the net force in all directions must be equal to zero...
  36. R

    Static Equilibrium Weight Problem

    The mass of the sign shown is 28.5 kg. Find the weight supported by (a) the left support and (b) the right support. How do I set this problem up properly? Here is my set up even though I know its wrong. m = 28.5kg, mg = 279.3N Fl + Fr = mg Fl = mg - Fr t = torque, r =...
  37. I

    Static equilibrium ship problem

    Homework Statement You are on a pirate ship and being forced to walk the plank. You are standing at the point marked C. The plank is nailed onto the deck at point A, and rests on the support 0.75 meters away from A. The center of mass of the uniform plank is located at point B. Your mass is...
  38. P

    Static Equilibrium of climbing harness

    Homework Statement a climber with a weight of 734.2 N is held by a belay rope connected to her climbing harness and belay device; the force of the rope on her has a line of action through her center of mass. The indicated angles are θ = 36.5° and ϕ = 29.0°. If her feet are on the verge of...
  39. G

    Static Equilibrium and tension of a beam

    Homework Statement In the figure below, a uniform beam of weight 520 N and length 3.4 m is suspended horizontally. On the left it is hinged to a wall; on the right is it supported by a cable bolted to the wall at distance D above the beam. The least tension that will snap the cable is 1200 N...
  40. G

    Static Equilibrium of pedestals

    Homework Statement A diver of weight 730 N stands at the end of a diving board of length L = 5 m and negligible mass. The board is fixed to two pedestals separated by distance d = 1.5 m. What are the magnitude and direction of the force on the board from the left pedestal? (Include the...
  41. G

    Solving Static Equilibrium: Find D for Tension of 1200 N

    Homework Statement In the figure below, a uniform beam of weight 520 N and length 3.4 m is suspended horizontally. On the left it is hinged to a wall; on the right is it supported by a cable bolted to the wall at distance D above the beam. The least tension that will snap the cable is 1200 N...
  42. M

    Static Equilibrium rope and ball problem

    [URGENT]Static Equilibrium problem A 11kg ball is supported from the ceiling by rope A. Rope B pulls downward and to the side on the ball. If the angle of A to the vertical is 22 degree and if B makes an angle of degree to the vertical find the tension in rope A. Homework Equations sum...
  43. S

    Static Equilibrium of Wheel-and-Axle System

    Homework Statement Consider the wheel-and-axle system shown below. a b m1 m2 Which of the following expresses the con- dition required for the system to be in static equilibrium? 1. b2m1 = a2m2 2. a2m1 = b2m2 3. am2 = bm1 4. am1 = bm2 5. m1 = m2 003 10.0 points Nobody at the...
  44. M

    Hi all - newbie question - Forces and static equilibrium

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  45. T

    Stability in blocks - static equilibrium

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  46. P

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  47. S

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  48. U

    Is Static Equilibrium Really That Simple?

    Hello! I'm a student from Norway, and I've been struggling with a static equilibrium for a few hours now. The terms I use might not be "right", but I'll try to explain the problem to the best of my ability. Homework Statement Find the forces Fa and Fb on this figure...
  49. J

    Static equilibrium: calculating force of tension

    Homework Statement The system (picture found in attachment) is in static equilibrium, and the string in the middle is exactly horizontal. Find a. Tension T1 b. Tension T2 c. Tension T3 d. angle (theta) Homework Equations sin=opp/hyp cos=adj/hyp The Attempt at a Solution a. Using...
  50. J

    Static equilibrium & force of friction

    Homework Statement A window cleaner of mass 95 kg places a 22-kg ladder against a frictionless wall at an angle of 65 degrees with the horizontal. The ladder is 10m long and rests on a wet floor with a coefficient of static friction equal to 0.40. What is the maximum length that the window...
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