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. T

    Statics: Incline plane an friction

    Ive been working on this problem for a little while now and basically, I don't know where to go. I have found the friction angle of 7 degrees but I really have no idea where to go next. My book doesn't have any examples like the problem. The problem looks a lot like a basic physics problem so I...
  2. Cyrus

    Can we accurately predict the shape of a cable system with multiple unknowns?

    I am studying the statics of cable systems and I find it to be very interesting. :approve: I REALLY like statics. :biggrin: Such an interesting subject, anyways. My first question is this: When we have a system of cables supporting weights, say like traffic lights, we can assume the cables...
  3. J

    Is this Friction Problem Really That Simple? A Scientific Analysis

    Ok this problem seems way too simple. I have worked it out without using any of the dimensions given. The problem is http://www.engr.colostate.edu/~elblunto/problem.jpg" My work is http://www.engr.colostate.edu/~elblunto/jonwork.jpg" I don't think the solution could be that easy...
  4. J

    Take Engineering Statics Online: Is it Worth It?

    I need to take Engineering Statics next semester, but the only time the class is offered conflicts with another class I have to take. There is no other class that I can take for my major next semester becasue every other class I need requires these classes I am taking next semester as...
  5. M

    Statics Question Help: Determine Resultant & Inclination

    Hi everyone, I have a statics question I am having a bit of trouble on. I don't know how I will put the diagram in here that it comes with but the question is "Determing the resultant of the coplanar concurrent force system shown. Compute the magnitude, sense, and angle of...
  6. P

    Statics: Equilibrium of Machines

    The problem is stated in the picture. And I drew the FBDs of the top half of the bolt cutter, as shown in the second page: Setting moment about A to be 0, I obtain -Q(1 in)-FBy*4 in=0 And By= -Q/4 lb Then setting moment about C to be zero. I obtain FBy(0.5 in)-20 in(75 lb)=0 Substitute in By...
  7. B

    Why Can't I Achieve Equilibrium in My Truss Analysis Problem?

    Hello, I'm having trouble with a truss analysis problem. We are supposed to use the method of joints & the method of sections. We have to find all the external reaction forces and internal member forces. The method of joints is not problem, and I THINK I'm doing the method of sections...
  8. T

    Which Statics Book Do You Recommend for Reference?

    Posted in different section decided to move this post here I'm currently using Statics: Analysis and design of systems in equilibrium by Sherri D sheppard. My classmates and I want another statics book for reference. We are looking into Vector Mechanics for Engineers, Statics and...
  9. T

    What are the Best Reference Books for Studying Statics?

    I'm currently using Statics: Analysis and design of systems in equilibrium by Sherri D sheppard. My classmates and I want another statics book for reference. We are looking into Vector Mechanics for Engineers, Statics and Dynamics 7e Ferdinand P. Beer (Author), Jr., E. Russell...
  10. T

    Statics: Mechanical Equilibrium

    I need some help in this problem to see if my game plan is right. My answer doesn't make sense, well to me it doesn't. A weight of 200 lb hangs from a frame of negligible weight, as shown. If the frame is in equilibrium, determine the loads acting on the frame at A and D. Use the fact that...
  11. D

    Help needed on statics, and also to check my answers

    I have this assignment to hand in and I've been having problems remembering how to do these problems. I am not sure if my answers are correct. I have no idea how to do the third one if anyone can walk me through the solution. My answers are: #1: -59.8 #2: Tension=14715N Mechanical...
  12. N

    Free way Sign Problem - Statics

    Q. The base of the freeway sign is attached to its foundation with four bolts.The four bolts must be able to resist the twisiting of the pole that is caused by the wind. Assume each bolt carries the same force. If the diameter of the bolt circle is 0.9m, calculate the horizontal (shear) force on...
  13. G

    Urgent Help Needed for Statics Course Test Prep - Four Problems Explained

    I need urgent help in Statics I'm taking a Statics course in college right now. However, I wasn't able to get a book due to financial issues early on. Naturally I feel behind. Anyways, I have a test coming up and the teacher gave us four problems to solve as a study guide, saying similar...
  14. N

    How Do You Calculate Friction and Normal Force on an Incline?

    Q. A Man, is pushing a copier machine, up an incline, which weighs 600 N. I need to find the frictional force, and the normal force. The free body diagram, I shall describe that to you. Weight of the machine acting downards. and if we resolve this weight we get mg sin theta along the...
  15. Cyrus

    Statics of Ropes and Cables

    First, on an unrelated note, I would like to share an anwser I think I found to be correct on a question I posted here a while back. I asked about how a smooth collar that was Not Pinned could prevent a moment. The problem I was faceing was the fact that in order to have "play" so that the...
  16. M

    Statics: Magnitude of vectors HELP

    Statics: Magnitude of vectors HELP! Could someone just tell me how to start this problem. I can't seem to think of anything right now.
  17. Cyrus

    Reviewing statics and came across this problem

    Im reviewing statics and came across this problem. There is a beam pin connected at one end and roller connected on the other. There is a moment at the pin and a force somewhere along the beam. Then they section it to find the internal normal shear and moment. One of the things i found slightly...
  18. T

    Solving a Spring Problem in Engineering Statics

    Spring Problem I need some help or hints on this exercise When a certain linear spring has a lenth of 180mm, the tension in it is 170N. FOr a length of 160mm, the compressive force in the spring is 130N. a. What is the stiffness of the spring in SI units? In U.S. Customary units? b. What...
  19. N

    What Is the Maximum Angle Theta for Equilibrium in a Statics Weight Problem?

    One end of a uniform meter stick is placed against a vertical wall. The other end is held by a lightweight cord that makes an angle theta with the stick. The coefficient of static friction between the end of the meter stick and the wall is 0.370 . What is the maximum value the angle theta can...
  20. N

    Seesaw: simple statics problem?

    Seesaw: simple statics problem? Q: A uniform seesaw is of length 3.90 m and weighs 235 N. The seesaw is pivoted about a point on its bottom surface and the location of this pivot along the length of the seesaw can be adjusted as far as a distance 0.170 m from the center of the seesaw. Little...
  21. C

    Solve Statics Problem for Bone Rongeur Machine Force at E

    Here's the problem: "The bone rongeur shown [refer to attachment] is used in surgical procedures to cut small bones. Determine the magnitude of the forces exerted on the bone at E when two 25-lb forces are applied as shown." I understand that this "machine" can be broken into 4 free-body...
  22. C

    Statics - 3D equilibrium problem

    Here's the question: "A camera of mass 240g is mounted on a small tripod of mass 200g. Assuming that the mass of the camera is uniformly distributed and that the line of action of the weight of the tripod passes through D, determine (a) the vertical components of the reactions at A, B, and C...
  23. J

    Statics Help Needed Desperately: Determine Forces on Frame

    statics help needed...desperately! The Frame in the Attached file supports a suspended weight W = 40 lb. Determine the forces on members ABCD and CEG. (image available at my website... http://geocities.com/jessparker502 I know how to calculate the forces when the wheel isn't present...
  24. P

    Help Padford with Statics Homework: Friction Formula

    now on question 8 of my homework, and i am starting to wonder if i;ve been getting these question right. :yuck: It's to do with friction. Relativally simple question: When an object is stationary, would the formula to find the resolved friction be: F = (mew, u) R or F (is...
  25. S

    Easy Question about Fluid Statics

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  26. T

    Struggling with Statics Problems? Need Help with Equations?

    I would like to know if anyone could help me with the attached statics problems. I've worked on these for quite sometime and haven't been able to figure them out. Thanks
  27. S

    Need Help with a Physics Statics Problem Involving Cords and Pulleys?

    Hey, I'm having a lot of trouble with this physics homework problem: The cords BCA and CD can each support a max load of 100 lbs. Determine the max weight of the crate that can be hoisted at constant velocity, and the angle theta for equilibrium. The picture shows B attached to a pulley on...
  28. S

    Statics and the cross product

    In the problem: A horizontal boom supporting the sign is of uniform construction and weighs 50 N. If the sign weighs 150 N, the tension in the supporting cable is? Could I use the cross product and if so how? The answer is 350 N.
  29. S

    Where to Find Statics Practice Problems for Physics Re-Test Preparation?

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  30. S

    Cable tension statics problem

    1.) A uniform rod AB is 1.2 m long and weighs 16 N. It is suspended by vertical strings AC and BD. A block P weighing 96 N is attached at E, .3 m from A. The tension in the string BD is? http://img116.exs.cx/img116/2822/STATICS1.jpg I did: (.3m)(96N)+ (.9m)(16N) - (1.2 m)(x) = 0 x=36N...
  31. C

    This time its a statics problem

    A nonuniform bar is suspended at rest in a horizontal position by two massless cords as shown. One cord makes the angle theta1 = 36.9 with the vertical; the other makes the angle theta2 = 53.1 with the vertical. If the length L of the bar is 6.10m, compute the distance x from the left-hand end...
  32. C

    This time its a statics problem

    A nonuniform bar is suspended at rest in a horizontal position by two massless cords as shown. One cord makes the angle theta1 = 36.9 with the vertical; the other makes the angle theta2 = 53.1 with the vertical. If the length L of the bar is 6.10m, compute the distance x from the left-hand end...
  33. D

    How do I solve internal force problems in statics?

    Please Help! Internal Forces in Statics I have been attempting to answer the problems on my Statics assignment for about a week now but I have not been so success full. I have only be able to answer on of the problems the other three below I get stuck on. Can someone please help me get past...
  34. O

    Engineering Statics problem

    Please Help !Engineering Statics problem i got a hard professor, been tryin to work out this problem for days. still stuck, please him. i don't know wat to do,
  35. M

    Is it possible to do statics and dynamics at the same time?

    I have finished university level physics and calculus classes. I am planning to take both Statics and Dynamics next semester at the same time. I am just looking for a passing grade. Is it possible to do Dynamics simultaneously with Statics? I am willing to put few weeks to look into...
  36. L

    Solving Statics Truss Problems: Plotting Force in Member BC & Angle ø Range

    The question is stated below. I found out an answer but it doesn't seems to be correct to me. I made a few sketches to clear things up a bit, sorry for bad quality, too much compression. The simple truss of Prob. 4/2 is modified as shown in the figure, in that the angle of the support surface...
  37. D

    What is the force on the handle in a statics problem using Excel?

    I have a problem in statics that I must use excel to do and my instructor modified the given question in a few ways to allows to use the capabilities of excel to find what the question asks for. http://herograw.com/5-51.JPG These are my instructors additions: If the whole excel...
  38. S

    Understanding Statics: Examples in Computer and Electrical Engineering Problems

    Question about Statics! Hey I'm having trouble finding examples of statics in different engineerings. See i ave this homework assignment where i have to look up an example problem of either computer or electrical engineering. The catch is that i have to find a problem related with statics...
  39. E

    Sample Exam Problem 2 Help | EM223 Statics | NEGAHBAN

    I am trying to solve the problems on a sample exam, I am stuck on Problem 2, can anyone help? I can't get to help until tomorrow! Thanks! http://em-ntserver.unl.edu/NEGAHBAN/EM223/sexam2/sexam2.htm
  40. A

    A couple of statics questions

    Hi, I have a couple of questions from a statics assignment that I'm in need of help on. Here's what I have so far: http://216.170.11.226/pub/6131.jpg Two rods are connected by a slider block as shown. Neglecting the effect of friction, determine the couple Ma required to hold the system...
  41. M

    Can Someone Explain Statics and Torque for an Applied Maths Exam?

    Hopefully someone here knows what I'm talking about, but here it goes. I'm doing my leaving cert applied maths paper in 2 days time, and I'm stuck on this question. I can't follow the solution available on the internet, so i need someone to go through it step by step. Its Q7 in the paper...
  42. K

    Mechanics 2 - Statics of rigid bodies. Please help.

    I'm having difficulty with the question, perhaps mainly because it is consists completely of unknowns, with little or no numbers. Help, in the form of steps to reach the proof would be much appreciated: 'A uniform ladder of mass M rests in limiting equilibrium with one end on a rough...
  43. S

    Help with Statics Problem | Shaun

    Please help with this problem: http://labphysics.uncc.edu/Phys2101/001/Test3A-001-F94.html #4 Please any help would be greatly appreciated. AOL SN: spatel600 Please let me know. Thanks. Shaun
  44. P

    How do I solve this challenging mechanic statics problem?

    I have a problem for HW that is driving me crazy! A copy of the original problem from the text is attached. Here is what I have done so far... First, I split the area under the force horizontally into two triangles and found the centroid of each. Centroid of upper triangle is 3m from...
  45. F

    What is the best approach to solving this Statics problem?

    Argh! Statics is a pain. Argh, this problem is killing me. I've tried a couple of approaches to this proble. First approach was to break it into 4 'Y' shaped vectors with with points A,B,C,D as the centers of the 'Y'. No avail. The next approach was to couple the forces to the origin but the...
  46. P

    What is an extension in a statics problem?

    I've yet to taken a statics class yet, only physics one, but I'm having a hard time trying to define what an extension is on one of my home work problems. The problem is kind of long(about a page long), hopefully I will be giving a enough info on my problem. Here goes You have a pin jointed...
  47. F

    Calculating Reactions at C & D Using 2 Force System | Step-by-Step Guide

    i attached a picture of what it looks like. I am supposed to find the reactions at c & d, and the reactions at a & c. i think its supposed to be done using a 2 force system. i have no clue how to even start this.
  48. P

    How can I solve for W in this tricky statics problem without exceeding 1050N?

    I am having trouble with a HW question that has been driving me crazy for a few days now. I have to solve for W ( a hanging weight) that will not cause either T1 or T2 to exceed 1050N. So far I have drawn the free body diagram that is attached as a word doc, and the angles I found based on the...
  49. F

    What are the Moments and Forces in These Statics Problems?

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  50. F

    Statics lever and valve question

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