What is Statics: Definition and 902 Discussions

Statics is the branch of mechanics that is concerned with the analysis of (force and torque, or "moment") acting on physical systems that do not experience an acceleration (a=0), but rather, are in static equilibrium with their environment. The application of Newton's second law to a system gives:






F


=
m


a



.


{\displaystyle {\textbf {F}}=m{\textbf {a}}\,.}
Where bold font indicates a vector that has magnitude and direction.





F




{\displaystyle {\textbf {F}}}
is the total of the forces acting on the system,



m


{\displaystyle m}
is the mass of the system and





a




{\displaystyle {\textbf {a}}}
is the acceleration of the system. The summation of forces will give the direction and the magnitude of the acceleration and will be inversely proportional to the mass. The assumption of static equilibrium of





a




{\displaystyle {\textbf {a}}}
= 0 leads to:






F


=
0

.


{\displaystyle {\textbf {F}}=0\,.}
The summation of forces, one of which might be unknown, allows that unknown to be found. So when in static equilibrium, the acceleration of the system is zero and the system is either at rest, or its center of mass moves at constant velocity. Likewise the application of the assumption of zero acceleration to the summation of moments acting on the system leads to:






M


=
I
α
=
0

.


{\displaystyle {\textbf {M}}=I\alpha =0\,.}
Here,





M




{\displaystyle {\textbf {M}}}
is the summation of all moments acting on the system,



I


{\displaystyle I}
is the moment of inertia of the mass and



α


{\displaystyle \alpha }
= 0 the angular acceleration of the system, which when assumed to be zero leads to:






M


=
0

.


{\displaystyle {\textbf {M}}=0\,.}
The summation of moments, one of which might be unknown, allows that unknown to be found.
These two equations together, can be applied to solve for as many as two loads (forces and moments) acting on the system.
From Newton's first law, this implies that the net force and net torque on every part of the system is zero. The net forces equaling zero is known as the first condition for equilibrium, and the net torque equaling zero is known as the second condition for equilibrium. See statically indeterminate.
A physicist who does research in statics is called a statician.

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  1. S

    Moments of Inertia Explained: Helping Scott Understand Statics

    Hey there, In my statics class we're just finishing up moments of area or moments of inertia as they're being called. I can do the math and figure them out just fine but I have no clue what I'm actually finding! What is it? I am having trouble actually conceptualizing what it is that I'm...
  2. RioAlvarado

    Balancing Normal Forces (Statics).

    Homework Statement A horizontal uniform bar of mass 260 kg and length L = 3.0 m is placed on two supports, labeled A and B, located as shown in the diagram. A block of mass 60 kg is placed on the right end of the bar. Find the normal forces FA and FB exerted on the bar by the supports. Enter...
  3. J

    What is the process for finding the moment of inertia for a semicircle?

    Homework Statement Find lx and ly. The Attempt at a Solution So after countless studying of this topic, and no notes from my professor to help, I thought I had the process figured out. But this initial image is throwing me off a bit. Here's what I believe to be the right process for these...
  4. J

    Statics- determining reactions

    I'm currently reviewing for a final tomorrow, I need to score a B on the final to stay in school. I'm beginning to panic as I've reviewed all day and have gotten nowhere. 1. Homework Statement The tension in the cable AB is 800 lb. Determine the reactions at the fixed support C. The Attempt...
  5. E

    Statics Problem 4/49: Method of Sections

    Homework Statement Determine the force in member BE of the loaded truss. See the attached picture. Homework Equations Sum of the Moments = 0 Sum of the Forces = 0 The Attempt at a Solution [/B] Sum moments about A to get: -12L - 56L +40Dy = 0 Dy=1.7L Sum the forces in the y...
  6. J

    Statics problem involving moments and reaction forces

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  7. T

    Computing max tensile and compressive stress in a bar

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  8. C

    Determining the forces in three cables.

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  9. A

    Difference between statics, dynamics, kinematics and kinetics

    Dear All, I am often get confused when four terms STATICS,DYNAMICS,KINEMATICS and KINETICS are used in physics Mechanics.can someone please differentiate between these four terms.i will be thankful.
  10. J

    Solid hemisphere resting on an inclined plane

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  11. J

    Statics, moment on submerged surface problem

    Homework Statement [/B] Shown below is a slew gate controlling the flow of salt water flowing into fresh water in a submarine depressurising chamber (used to measure the pressure depth and which is compared to a control signal that has been calibrated). On the inlet side, the depth of...
  12. T

    Engineering, Statics -- A pulley is free to move on the cable

    Homework Statement 1. Pulley B is free to move on the cable ABC which is fastened at A and being pulled by force F through the pulley C. Neglecting friction: a. Determine location of point B as a function of d. b. Express the force F required to maintain equilibrium in terms of P...
  13. hdp12

    Given Moment about a Pin and a Roller

    Homework Statement For my statics homework, we are directed to: Draw the free body diagram and use the force and moment equilibrium to determine the support reactions for the following systems I'm having a bunch of trouble with problem 4.10, which is displayed in the following picture I'm...
  14. B

    Need help with mechanics statics; finding resultant force

    Hi! Can anyone help me with these problems? When I try to draw a parallelogram, I couldn't find the angles. Please help. http://imageshack.com/a/img673/8733/GsXt9f.jpg http://imageshack.com/a/img910/1949/1AB7iB.jpg
  15. D

    Statics Question -- Bar and roller resting on a circular surface

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  16. D

    How Do I Solve These Mechanical Principles Problems in Electronic Engineering?

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  17. L

    Fluid statics- pressure intensity and hydrostatic force

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  18. J

    Introductory Torque Statics Problem

    Homework Statement You're carrying a 4.0-m-long, 24kg pole to a construction site when you decide to stop for a rest. You place one end of the pole on a fence post and hold the other end of the pole 35 cm from its tip. I've drawn a diagram of the problem on Paint... Homework Equations ∑τ=0...
  19. T

    Calculating Tension in a Static System

    Homework Statement Homework Equations The answer in the back on the book shows 4.06i -7.61j + 5.07k. I do not understand why my signs are backwards.The Attempt at a Solution I ended with -4.06i +7.61j - 5.07k
  20. J

    Solving a Moment Problem: Find the Answer!

    Homework Statement There is a copy of the problem in the picture with the graph. Homework Equations M = F*d, M = Fxr, F_x = Fcos(theta), F_y = Fsin(theta) where theta is measured off the positive X axis, The Attempt at a Solution I tried splitting the force vector into X and Y components and...
  21. J

    Solve Statics Homework: Determine Moments of 5.6-kN Force

    Homework Statement This problem is from WileyPLUS. I've been looking through my book, but none of the methods they present work for me. I guess I just don't know how to use them properly. Determine the moments of the 5.6-kN force about the point O and about point B. Homework Equations I...
  22. M

    Yet another statics problem involving several forces

    Homework Statement The body is connected to the ground with a moving joint at B, the body slides with no friction at A. Homework Equations ΣF=0 => ΣFx=0 & ΣFy=0 ΣM=0 The Attempt at a Solution First I made a drawing: At this point I started calculating: ΣFx=>P-R2-F1, so: P=R2+F1 ΣFy=>...
  23. C

    Simple Statics Question: Truss Structure

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  24. M

    Statics problem involving several forces

    There isn't much data, I'm just supposed to simplify the drawing of the body OA and find the forces. The body has a mass m and is connected to the ground with a moving joint in O. Below I post the drawing that I made. I changed the line into a force S, which I then divided into Sx and Sy. I...
  25. S

    What is the Tension in the Tower Crane Cable?

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  26. E

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  27. E

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  28. K

    What am I doing wrong on this Statics Problem?

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  29. J

    Vector Addition Problem - Statics

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  30. D

    Understanding Statics Analysis for a Simple Square Truss Design

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  31. A

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  32. A

    {statics} Kvartil (quartiles) why I didnt get right solution ?

    Homework Statement On this vector I didnt get the right answer: x = [ 5 8 10 11 137 ] [/B] q3: i = (p/100)*n = (75/100)*5 = 3.75 >> 4th in vector is 11 q1: i = (25/100)*5 = 1.25 >> 2nd is 8 in MATLAB is solution Homework EquationsThe Attempt at a Solution
  33. L

    Statics Problem Help: Can't Get It Right - M=5860lb ft Off by 4

    Please Help! I've been working on the problem for all day now and can't seem to get it right. One of my attempts came close to the answer in the back of the book but was off by about 4, the it should be at 30 degrees M=5860lb ft, and I got 5856. Along with this I have to enter the equations into...
  34. Z

    Fluid Statics: Find vertical and horizontal forces in tank

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  35. F

    Can you check my solution for this trusses problem

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  36. Soumalya

    References to Engineering Mechanics

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  37. ME_student

    Another Statics problem with friction

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  38. ME_student

    Solve Statics w/Friction Homework: P Force for Cabinet Movement

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  39. Roodles01

    Fluid Statics - net upward force

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  40. T

    Finding Force in Element D-C of a Truss

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  41. P

    Where Did I Go Wrong with My Hydraulic Car Lift Plot?

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  42. Feodalherren

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  43. G

    Help with Statics: Failing to See Force Fbc's Angle

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  44. ME_student

    Yet, another statics problem

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  45. N

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  46. Feodalherren

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  47. Feodalherren

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  48. P

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  49. R

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  50. Feodalherren

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