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. J

    Static equilibrium wine bottle holder

    Was looking for some assistance in setting up the force and torque balance equations for one of those wine bottle holders where the holder is nothing more than a tilted board with a hole in it. I understand that the C.G. of the system needs to be directly above the base of the board but I want...
  2. P

    How Far Can You Safely Walk on a Pole to Rescue a Cat at the Grand Canyon?

    I've a test soon, and I've been thinking about this, and not quite sure how to approach it. I think I understand the chapter, but I can't seem to get it. A uniform 210lb telephone pole is sticking out over the Grand Canyon (32 feet of it is sticking out) with a massless cat stuck at the end...
  3. B

    Confusing static equilibrium problem

    static equilibrium problem A 900-N boy sits on top of a ladder of negligible weight that rests on a frictionless floor as in http://m.domaindlx.com/barnsworth/physics.JPG. There is a cross brace halfway up the ladder, and the angle at the apex is 30 degrees. a) What is the force exerted by...
  4. B

    Static Equilibrium and a uniform rod

    One end of a uniform 4.00-m long rod of weight Fg is supported by a cable. The other end rests against the wall, where it is held by friction. The coefficient of static friction between the wall and the rod is = 0.500. Determine the minimum distance x from point A at which an additional...
  5. P

    Static Equilibrium of a building

    A 50 story building is being planned. It is to be 200 m high with a base 56 m by 70 m. Its total mass will be about 1.8 X10^7 kg and its weight therefore about 1.8 108 N. Suppose a 200 km/h wind exerts a force of 1000 N/m2 over the 70 m wide face (Fig. 12-86). Calculate the torque about the...
  6. S

    Problems regarding static equilibrium

    Hey all... thanks for looking. I've got three questions that I'm having trouble with... I have some crap done on them, but I'm just plain stuck... can someone help me out with all 3? I need to be done these like yesterday so I can get my mark to the university. :cry: I scanned in the...
  7. Z

    Static Equilibrium and frictionless inclined plane

    there is an object suspended on a frictionless inclined plane by a rope parallel to the incline. (the tension in the rope is 5000N). The angle on the incline is 25. I need help to find the weight of the object, I've tried everything! Thanks.
  8. A

    How Do You Calculate Forces in a Static Equilibrium Problem with Pulleys?

    Hi, I was wondering how to analyze the forces in a simple static equilibrium problem I have been contemplating. Suppose you have two pulleys attached to a wall and aligned horizontally with a loop of wire around them, and you hang a weight from the lower strand of wire. I'm stuck trying to...
  9. Juntao

    Static equilibrium helpprobably simple

    I've added a picture. The system shown to the right is in equilibrium with the center string exactly horizontal. Mass # 1 = 42 kg. Mass # 2 = 50 kg. È = 31 degrees. =========== A) Tension in left most string? B) Tension in center string? C) Tension in right string? D) What is the...
  10. ShawnD

    Solving a Static Equilibrium Problem with Multiple Variables: A Case Study

    Here is a problem I have to solve http://myfiles.dyndns.org/pictures/statics9-2.png The load W is 1250lbs. The force exerted by the hydraulic thing GJ is 0 which makes HF a 2 force member. What I am supposed to do is solve for the tension in spring DE I just can't seem to get an...
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