What is Free body: Definition and 288 Discussions

The term free body is usually associated with the motion of a free body diagram, a pictorial device used by physicists and engineers. In that context, a body is said to be "free" when it is singled out from other bodies for the purposes of dynamic or static analysis. The object does not have to be "free" in the sense of being unforced, and it may or may not be in a state of equilibrium; rather, it is not fixed in place and is thus "free" to move in response to forces and torques it may experience.

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  1. A

    What is the convention for writing vector magnitudes in free body diagrams?

    Do you normally write the magnitude of the vectors in free body diagrams? I have homework on this. Is there any convention when writing the magnitude?
  2. Jadaav

    Free body diagram - Weight and normal reaction

    Let's consider a stationary ball lying on the floor. The weight of the ball acts downwards and the normal reaction acts upwards. They are of the same magnitude but not of the same type. So normal reaction is the reaction to what, if not weight ?
  3. N

    Free body diagram of person in elevator Help

    Homework Statement A man is on an elevator - Draw a FBD of the man if the elevator accelerates upwards - Draw an FBD of the man if ele. accelerates downwards Homework Equations F=m*a w=mg The Attempt at a Solution My FBD For the first one "elevator accelelartes upwards" means...
  4. C

    What are the forces acting on the chandelier?

    Homework Statement See picture. Homework Equations The Attempt at a Solution I want to know what are all the forces acting on this object. If the object is 10N , the tension force suppose to be 10N. But wouldn' there be a normal force acting between the point touching the...
  5. F

    Finite Element analysis: Free body diagram help

    Homework Statement Hey guys, my problem is not really the end solution, but the preliminary step that I'm not too sure about. Given the following diagram: The image on the left is the given model, and the right image is my nodal element FBD, but somehow i don't believe that's correct. Can...
  6. N

    Draw a free body diagram of each object in centripetal acceleration

    Homework Statement Draw a free body diagram of each object in Italics, that is in centripetal acceleration, and name the force causing this centripetal acceleration. a. Moon in circular orbit around Earth. b. Electron in circular orbit around nucleus of atom . c. Snowboarder slides over...
  7. A

    Dynamics, Newton's laws, Problem with free body diagram and work

    Homework Statement A boy skateboards down a curved playground ramp. If we treat the boy and his skateboard as a particle of total mass m = 25:0 kg, he moves through a quarter-circle with radius R = 3:0 m. He starts from rest at point A and there is no friction. (a) Find his speed at the...
  8. J

    Pulley free body question - what am I doing wrong?

    Homework Statement Note that the FAQ is not clear if I am required to use LaTeX for formatting formulas. I have not used LaTeX, but I will retype my question if I am violating the rules. Please let me know :-) Non-extensible cable attached to ceiling. Cable goes down, around a pulley and...
  9. J

    18 Free body diagrams, statics

    Hi to everybody Homework Statement Well I need to identify the forces acting on the bodies using free body diagramas, it´s not necessary to calculate anything, it´s only to learn about free body diagrams. I will write my thoughts about the FBD and I will appreciate a lot if you see that I´m...
  10. R

    Free Body Diagram to find Force

    The attached image shows a diagram of the problem. I am trying to calculate the Compressive force in the piston (B). Would the methods shown work for finding the Comp Force? Thanks
  11. N

    How Do You Analyze Forces in a Non-Slipping Book Stack Scenario?

    A hand supports two books, ma and mb, with ma on top. The hand accelerates the books p and to the right, with a pushing force directed 64° above horizontal. Assuming the upper book does not slip, draw a free body diagram for each book. My attempt:
  12. S

    Pulley Hoist Free Body Diagram

    Hi All, I am an old dog, and rusty propeller head. I am having the most difficult time figuring out the forces on a pulley system I am working on. Can someone please review my sketch and tell me if I am even close. I would accept any suggestions and direction. Much Obliged -Steve
  13. F

    Maximum angular velocity and free body diagram

    Homework Statement I have found the question I am having trouble with here: http://www.chegg.com/homework-help/questions-and-answers/block-mass-m-rest-surface-incline-adistance-h-10cm-base-height-incline-ish-50cm--coefficie-q218123 Homework Equations See below The Attempt at a Solution After...
  14. G

    What is the Acceleration of a Couch Being Pushed at an Angle with Friction?

    Homework Statement An 82 kg couch is being pushed with a force of 56 N at an angle of 40 above horizontal. If the coefficient of friction between the couch and the floor is 0.051, what is the acceleration of the couch? Homework Equations The Attempt at a Solution
  15. J

    How to interpret a Free Body Diagram for a Kite in Flight?

    The wind is blowing with a force of 48 N against a kite that Taylor is flying, so that the tail of the kite makes an angle of 24° to the ground. I am just really confused on this, I attacted the solution would anyone mind explaining it? I have no idea on how to get this
  16. P

    Understanding Free Body Diagrams for Cantilevered Structures

    For the attached picture I need to draw a free body diagram for the structure supporting the pulley. At the fixed end (left), there would be a vertical and horizontal reaction force as well as a moment. I am not sure what the forces and moments would be for the part connected to the...
  17. T

    Free Body Diagram and applied force

    Homework Statement A cavewoman is dragging her 65.4 kg mate home, up a gentle 10° incline. The co efficient of friction for skin on oil is 0.40. What is the minimum applied force she needs to keep the neanderthal moving with uniform motion? Homework Equations ff=μFn fg=mg fnet=ma The...
  18. V

    Wrote general equation for a free body diagram

    So I derived this equation for the net force/acceleration of a motorcycle on a flat surface. I believe this equation could practically be used for any rolling object. ƩF = Fp - μ*Fn - FD Where: FP is the force of the bike acting against the ground, tangent to the ground FD =...
  19. L

    Free Body Diagrams: Easily Analysing Photos & Sketches

    Hi, When looking at a photo or sketch, I find it hard to take out the important bits and turn it into a freebody diagram. I am doing this question (pic attached). Im quite unsure how to even begin. I've though of a few ways to start analysing it. The first way analyses AD as a whole. And...
  20. M

    Free body diagram on moment and torsion

    Homework Statement It's not exactly a homework question, just want to see if i have the right concept in drawing free body diagrams See attached Picture. In case 1, the object is fastened on plane x-z and the rectangular block is fastened to the T-block in y-z plane. Will the force be...
  21. V

    Is the Free Body Diagram for C-Spanner Screw Failure Analysis Correct?

    Hi guys, I'm working on one assignment about C-Spanner screw an impeller failure analysis. However, we're unsure if the free body diagram we draw is correct or not, given that our calculated safety factor is unreasonable. Can anyone give us a hand and have a look. Moreover, if someone can...
  22. 1

    Free body diagram of man in a box

    Homework Statement A 60 kg man stands in a 30 kg box on a light weighing machine. If the box is kept at rest due to force applied by the man by the rope , what is the weight shown by the weighing machine? Homework Equations The Attempt at a Solution .answer given in book is 15...
  23. K

    How Do Forces Interact in Stacked 45 Degree Wedges with Friction?

    Homework Statement How would the free-body diagram of two 45 degree right angle wedges stacked on one another look like? (It is stacked so that the two wedges form a square) There is friction that is holding the wedges together. The wedges are in place and not moving. ___ |\ | | \| ----...
  24. 1

    Accelerating Car Free Body Diagram

    Homework Statement Identify all forces acting on the object and draw the free-body diagram. Draw the force vectors with their tails at the dot. The orientation of your vectors will be graded. The exact length of your vectors will not be graded but the relative length of one to the other...
  25. M

    Forces acting on a two object system using free body diagram

    Homework Statement A force of magnitude F= 7.30 N pushes three boxes with masses m1= 1.80kg, m2= 3.00kg and m3= 4.20kg, on a level surface. Draw a free body diagram showing all the individual forces acting on the system consisting of boxes 2 and 3 together. Indicate the directions of the...
  26. B

    Help drawing free body diagrams

    Homework Statement The picture attached is the problem. Also given is the constant acceleration of 2m/s^2, a frictional force of 75N, and the mass of block A is 25kg. Homework Equations The Attempt at a Solution I just need help with drawing the free diagram part involving the normal force...
  27. M

    Pulley Free Body Diagram Problem

    In the figure below, m1 = 10.5 kg and m2 = 3.5 kg. The coefficient of static friction between m1 and the horizontal surface is 0.50, and the coefficient of kinetic friction is 0.30. I've drawn the free body diagram myself and labeled it but don't know how to structure the equations and stuff...
  28. T

    What is the significance of F being a roller joint in this system?

    Homework Statement Assume the system is massless. The Attempt at a Solution Here is my quick attempt at drawing a free body diagram for this system: What I am not sure about is the direction of the force at F. Should the force be A or B?
  29. T

    Torque on a Free Body: Applying 1N Force to Ruler

    Hi everyone, I have a very simple and classic question here. Suppose I have a 10cm,0.01kg ruler (uniform density) in space. And I apply a 1N force 2 cm from the left end of it. What happened at this instance? I guess centre of the ruler will start to accelerate as a=F/m=100ms^2. But what...
  30. 1

    Free body diagram(its simple but i don't know why i can't understand it)

    Homework Statement If a 4kg block is placed on top of a 5kg block which placed on a friction less plane and a force is applied on the lower 5kg block ,For what maximum value of force will the top block not slide ? μ=0.036 Homework Equations The Attempt at a Solution The maximum static...
  31. K

    Free body diagram of a truncated cone?

    Hi, I have a question about basic statics. I have heard from someone that the forces acting on a truncated cone in a hole of corresponding geometry is different from an ordinary block sliding down a wedge, since the normal force on one side of the cone will be affected by the normal force on...
  32. K

    Free Body Diagram for simply supported beam

    Homework Statement As shown in the attachment, a free body diagram (FBD) must be drawn Homework Equations sum of horizontal force = 0 sum of vertical force = 0 The Attempt at a Solution 1. Forces F1 and F2 appear exactly as they are in the FBD 2. At point A, there is an outward horizontal...
  33. E

    Question related to SHM and free body diagrams

    Homework Statement Draw three free-body diagrams showing the forces acting on a toy suspended by a vertical spring. The diagrams should show the situations when the toy is at its equilibrium position, and above and below the equilibrium position. Homework Equations The Attempt at a...
  34. X

    Statics free body diagram concept question

    Homework Statement See attachments Homework Equations The Attempt at a Solution In the explanation attachment, I don't get the last paragraph "Note that force Fce acts downward on bar...compression." Since from the figure Fce is pointing down, and Fbd is pointing up, shouldn't...
  35. U

    Free Body Diagram Help: Homework Equations and Attempts

    Homework Statement I feel that I am a bit fuzzy whether things are reaction forces. In the diagram I see there is a beam holding point B, and there are 3 forces: Cable BC, 500N, and 780N. My professor wrote: Ask yourself: is the beam holding the point from moving up or down, right or left...
  36. S

    Software to draw free body diagrams and vector diagrams

    Hello Could anyone recommend me a software to draw draw free body diagrams, vector diagrams, spherical/cylindrical coordinates systems etc. I am doing a project on electromagnetics and I am supposed to put everything in a digital format. Thanks
  37. B

    Free Body Diagram Help: Learn How to Draw It

    Homework Statement can anyone show me what the free body diagram of this would look like? Thankyou
  38. J

    Finding Applied Force with Free Body Diagrams (Grade 12 Physics)

    Homework Statement You have a 10kg object that is thrown down a building. The distance from the ground to the building is 50m. The initial velocity of the object is 5 m/s. What is the applied force and what force does the object hit the ground with? Homework Equations Fapp= Fnet+Fg...
  39. G

    Free body diagram problem assistance

    Hey, I'm having a bit of trouble with a Free Body Diagram question and I'm not sure if I'm going about it properly. The question asks; A 82kg couch is being pushed with a force of 56N at an angle of 40 degrees above the horizontal. If the coefficient of friction between the couch and...
  40. G

    Assistance in Free Body Diagram Question

    Hey, I'm having a bit of trouble with a Free Body Diagram question and I'm not sure if I'm going about it properly. The question asks; A 82kg couch is being pushed with a force of 56N at an angle of 40 degrees above the horizontal. If the coefficient of friction between the couch and...
  41. T

    Why Is the Direction of Friction on Block A to the Right?

    Homework Statement I attached a picture of the problem and I was wondering why the direction of the friction on block A is to the right. Shouldn't it be to the left because friction always opposes the direction of the acceleration (which is in this case to the right for block A)? Thanks!
  42. S

    Free Body Diagram Finding Moments

    Homework Statement I have to find the forces FGB FCB AND FGH http://desmond.imageshack.us/Himg696/scaled.php?server=696&filename=img59wa.gif&res=medium P1 = 5 kN, P2 = 10 kN, JY = 21.25 kN a1 = 2 m, a2 = 1 m, a3 = 0.5 m, a4 = 1 m, a5 = 2.5 m Angle FGH makes with the horizontal is: 26.57...
  43. S

    Free Body Diagram from Space Diagram

    Homework Statement http://desmond.imageshack.us/Himg804/scaled.php?server=804&filename=img1.gif&res=medium I have to change this space diagram into a free body diagram and i am struggling Homework Equations The Attempt at a Solution I have put a reaction force in the the x...
  44. S

    Force free body diagram problem on gym equipment

    I'm looking at the force required to move the weights, i have a few sketches attached on a word document with an idea of how the apparatus works. Will the force required to lift the mass increase as the player moves forward. Any help is appreciated as i am lost with this problem at the...
  45. A

    Uniform Circular Motion Free Body Diagrams

    Homework Statement A circular-motion addict of mass 82.0 kg rides a Ferris wheel around in a vertical circle of radius 14.0 m at a constant speed of 7.10 m/s. (a) What is the period of the motion? What is the magnitude of the normal force on the addict from the seat when both go through (b)...
  46. S

    Static Equilibrium Pulley and free body diagram

    Homework Statement Attached is the picture of the problem and my free body diagram. The system is in equilibrium. Homework Equations Fy = 0 Fx = 0 The Attempt at a Solution I'm having trouble solving the two equations that I arrive with... I use +x to the right, and +y up...
  47. R

    How Can I get started on drawing this free body

    Homework Statement (http://i.imgur.com/5OWEi.jpg) I have way to many unknowns to start the process of solving equations. Homework Equations ƩFx = 0 ƩFy = W The Attempt at a Solution I was given the answer of one force being .885W and the other is .201W. The problem is a...
  48. H

    Lagrangian equation from this free body diagram

    Homework Statement Here's the free body diagram with variables. I am looking for the lagrangian mechanics equation. M is mass of the bottom wheel. m is the mass of the top wheel. R is the radius of the bottom wheel. r is the radius of the top wheel. θ_{1} is the angle from vertical of...
  49. D

    Leaning Column Free Body Diagram

    This is a self-study homework problem. I am trying to verify the "falling column physics" associated with leaning forward with our center of mass in front of our feet. Homework Statement Describe the free body diagram for a column (tree, pencil, person) leaning from vertical. Assume there...
  50. A

    Understanding Projectile Motion: Free Body Diagram of a Tipcat

    Homework Statement Place a small wooden stick over the edge of a desk. Hit the end of the stick overhanging the table so that it flies away. Draw a free body diagram during the impact and after it flies away. Homework Equations Torque, Impulse, Angular momentum, Projectile motion, Moment...
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