What is Force diagrams: Definition and 24 Discussions

A free body diagram consists of a diagrammatic representation of a single body or a subsystem of bodies isolated from its surroundings showing all the forces acting on it.
In physics and engineering, a free body diagram (force diagram, or FBD) is a graphical illustration used to visualize the applied forces, moments, and resulting reactions on a body in a given condition. They depict a body or connected bodies with all the applied forces and moments, and reactions, which act on the body(ies). The body may consist of multiple internal members (such as a truss), or be a compact body (such as a beam). A series of free bodies and other diagrams may be necessary to solve complex problems.

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  1. I

    Construction Workbench Top Pulling Force With Sloping Leg

    Hello, I am making a workbench for my mancave, the front edge of the bench is supported by legs that slopes inwards at 78 degrees and the back/rear edge of the bench top is fixed to the wall. How do I calculate the force Q pulling the bench top away from the wall please? Also is the force Q...
  2. R

    Force Diagrams for a Combined Mass

    I know that the ##F_{AonB} = -F_{BonA}##, but I just wanted to check something. If object A is the truck, then the x-direction should have a vector coming from the force of the engine driving the truck forward, a vector pointing in the negative direction for friction, and a vector in the...
  3. L

    Man on an Elevator -- Force Diagrams

    I really need help figuring out where to start. I believe that every graph has a normal force pushing up on the person as well ag gravitational force pushing down on them. Where I am getting confused at is how the velocity plays into the scenario and if an acceleration of 9.8 m/s^2 downwards is...
  4. B

    How does the incline of the rod depend on mass and force F?

    Homework Statement We have a rod with length L and with the left end the rod is fixed to the ceiling in such a way it can swivel. As we can see from the picture (attached file) on right end two forces are acting on the rod: F and mg. The question is: How does the incline of the rod depend on...
  5. cjpa

    A Understanding Force Diagrams for Hydraulic Cylinder Selection

    Hello world, I have to select an hydraulic cylinder to counter-balance a force. For that purpose I need to know the force that my hydraulic cylinder must exert. Typically I would use the horizontal part of F2, but being that force with diferent degrees, doen't my friction play an important...
  6. W

    I'm making an Arithmetic Error, Electrostatic force diagrams

    Homework Statement Three charged particles are placed at each of three corners of an equilateral triangle whose sides are of length 2.7 cm . Two of the particles have a negative charge: q1 = -6.0 nC and q2 = -12.0 nC. The remaining particle has a positive charge, q3= 8.0 nC . What is the net...
  7. G

    Classic Static Electricity Balloon Example

    Homework Statement 1. Explain why a balloon sticks to a wall after being rubbed on your shirt (remember the wall is not metal and does not have "free" electrons") 2. Include a balanced force diagram that includes the electrical force and gravitational force (assume electrical force is twice...
  8. M

    Shear Force Diagrams: Uses, Benefits & Calculations

    Hi there, I have created lots of shear force and bending moment diagrams for simply supported beams. I have used the maximum value on the bending mement diagram for bending and stress equations, but I have never found any real use for the shear force diagram. Yes they tell you the distribution...
  9. S

    How to Draw Force Diagrams for Suspended Objects and Equilibrium Situations

    Homework Statement An object with a mass of 300 kg is suspended between two cables which sag at an angle of 40ᴼ below horizontal, on either side. Draw a free-body diagram. While driving in your car, you notice that the string holding the rosary to your rear-view mirror makes an angle...
  10. S

    How to Draw a Force Diagram for an Object Suspended by Strings?

    Homework Statement An object with a mass of 5 kg is suspended between 2 strings which sags at an angle of 52° Below horizontal on either sides. Draw a force diagram. 2. Attempt
  11. P

    Understanding Trig In Force Diagrams

    Hello, I have the following problem part (b) which I already solved as you can see in the attached image. So I am not asking homework questions, I merely reviewing my homework for a better understanding for the test. I obtained the answer from a friend showing me his method. However, I am...
  12. N

    Shear Force Diagrams and Bending Moment Diagrams

    Homework Statement http://img189.imageshack.us/img189/9131/22465062cfdd4934b51d7f5.png Hopefully the image isn't too difficult to decipher... Basically a beam balanced on to pin jointed pivots with 6 metres in between each one. Homework Equations ƩFy = 0 ƩFx = 0 ƩMP = 0 The...
  13. R

    Active Force Diagrams/ Virtual Work

    Homework Statement Homework Equations ? The Attempt at a Solution a) y=2Lcos(θ) x=2Lsin(θ) b) I haven't started the next question as I want to make sure the active force diagram is correct first.. If somebody could just check the diagram and help me with where I'm going...
  14. B

    Deriving Bending Moment Diagrams from Shear Force Diagrams

    Folks, I was checking to see was it possible to determine the bending moment diagram from the shear force diagram. Seemingly one can do it for simply supported beams but if we consider a rigidly supported beam on either end its not possible to derive the bending moment diagram from the shear...
  15. P

    Why is kinetic friction always lower than maximum static friction?

    I was reading about those in my textbook and they drew an example of a block resting on a ramp. The diagram showed the force of friction. How is there friction if the block is not moving? Thanks, Peter G.
  16. E

    Where do you put the angle in force diagrams?

    Homework Statement Ok, so I'm in college now. However, I'm having the same problem i did when I was in high school. When your doing a problem that has let's say a truck on a 30 degree incline, how do you decide whether that angle will be touching the y component of the angle or the x? The...
  17. S

    Reactions And bending moment and shear force diagrams

    Hi. I've been given this to calculate the support reactions but I'm not sure how to handle the increasing udl. And how would this be shown on a Bending moment and shear force diagram?? Also with non increasing Udl's when calculating the reaction is it best to change the udl to one force...
  18. I

    Calculating Force in a Rifle-Bullet System

    Homework Statement A rifle weighs 50.0 N, and its barrel is 0.750 m long. It shoots a 25.0 g bullet, which leaves the barrel at a speed (muzzle velocity) of 320 m/s after being uniformly accelerated. What is the magnitude of the force exerted on the rifle by the bullet? Homework Equations...
  19. C

    Net force, force diagrams, normal force

    In a problem whereby you want to calculate the net force of the rope lifting a box, and there is something in the box, whether you take into account the normal force. The forcees would be the tension of the rope, and the weight of the box and the object inside. To caculate the net force of the...
  20. C

    How Do They Calculate the 9 Degrees in the Force Diagram?

    Homework Statement http://img61.imageshack.us/img61/4585/8m1cdhx1.gif I understood every except, How do they get the 9 degrees in part c? Homework Equations The Attempt at a Solution
  21. S

    Shear force diagrams simple stuff hey?

    shear force diagrams simple stuff hey!? hey guys this is probably very straight forward stuff for u but i have an example question on a loaded beam. there is a UDL, 2 pure couples and 2 fixed points. now how do i do the shear force and bendin moment diagram for this really lookin forward...
  22. C

    Do Force Diagrams Show Forces Exerted by the Object?

    Hi, I have had a slight confusion on the Force and Free-Body Diagrams. I know that they are represented by arrows for the vectors in the direction of the force and that forces exerted on the object are shown. Are the forces exerted by the object also shown for the Force and Free-Body Diagrams...
  23. T

    Bending moment and shear force diagrams

    http://www.sendspace.com/file/czhuhx http://www.sendspace.com/file/gviky7 pls have and look at the link above and kindly tell me how to draw the bending moment and shear force diagrams.this is in the chapter of statics mechanics thanx
  24. D

    Help for High School Physics Student: Drawing Force Diagrams

    Hey all, I'm a junior in high school and taking physics. My teacher isn't really one of the best teachers, and we do nothing from a textbook, all done from her drawings/lectures from a whiteboard. It's safe to say I'm just about completely lost in that class. We have a test coming up...