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. E

    Help with free body diagram for circular motion

    Suppose you have an object (lets call it block A) resting on the edge of a circular rotating disk and sitting static on the disk. I'd like to visualize a free body diagram for this showing forces. These are the forces I believe are acting on it: - Fg - Force due to gravity - Fn - Normal...
  2. J

    Why Isn't the Child's Pulling Force Shown in the Free Body Diagram?

    I have a question for the question http://tinyurl.com/2mftmr The following is the solution for the question, and you can see the free body diagram for child only, chair only and chair and child as one system http://tinyurl.com/32ozt9 For the free body diagram of chair and child as one system...
  3. S

    Drawing a Free Body Diagram for Drainpipe in Forklift

    1. Hmm, I need to draw a Free Body Diagram for the picture posted below. 2. No relevant equations. Just a geometric diagram. 3. I've done what I think it could be using help from Wikipedia. Could someone tell me if its right? Am I missing any other forces? The original object...
  4. J

    Work done with free body released

    I have a question here http://tinyurl.com/2kgeun My attempts is mgx=(1/2)*kx^2 + (1/2)mv^2 where mgx is the potential energy of block m and (1/2)mv^2 is kinetic energy of block 2m. But this does not seem to work, because we don't have the value v. May I know how to solve it?
  5. C

    Free Body Diagram Examples and Tips for a Simple Assignment | Homework Help

    Homework Statement Hey guys. My Physics teacher gave us an assignment to make a Free Body Diagram poster. He didn't give us any specifics, just told us that we can do whatever we want. I'm a little confused as to what I should do and how to make one of these. Could you give me an example of...
  6. O

    Free Body Diagram and Newton's 2nd

    Homework Statement http://img527.imageshack.us/img527/2125/diagramkl0.png The Attempt at a Solution My attempt is in the picture. I am trying to get the diagram done before I continue on because if I mess up in the diagram, my work is guaranteed to be wrong. So basically what I am asking is...
  7. B

    Designing a Curved Highway Exit Ramp

    Hi everyone, I just need some help on setting up a free body diagram with the appropriate forces acting on it. The question is: An engineer must design a curved exit ramp for a highway in such a way that a car, exiting at the posted speed limit of 17.88 m/s (40 mi/hr), does not depend on...
  8. R

    Free Body Diagram and tension force

    Homework Statement It is supporting a weight of 500kg g= 9.81 Homework Equations The Attempt at a Solution Is the tension force a moment? im just not sure what i should do with it at that angle to get my FBD Any help would be tops! thanks a heap
  9. C

    What Forces Act on a Piano in a Free Body Diagram?

    Identify the forces acting on the object of interest. From the list below, select the forces that act on the piano. 1. acceleration of the piano 2. gravitational force acting on the piano (piano's weight) 3. speed of the piano 4. gravitational force acting on Chadwick...
  10. Simfish

    Free body diagram of a person sitting on a wheeled chair

    So I am a person sitting on a chair that has wheels. Now, the question is - can I push the chair when I am sitting on the chair and have nothing to push against? [other than the chair]? Note that I have no contact whatsoever with the floor. From experience, I know I can. So why? Whenever i...
  11. L

    Free Body Diagram Q&A: Atmospheric Pressure?

    Hi! Was wondering if anyone could enlighten me as to whether the atmospheric pressure is to be considered when drawing the free body diagram of a book resting on a table? In addition to the normal force and the weight, does atmospheric pressure need to be included?
  12. S

    Free body diagram for each vehicle

    Homework Statement In the movie "Jurassic Park 2", a jeep is struggling to pull a trailer back up from over a cliff. The jeep is connected to the trailer by a cable. The jeep in on level ground and the trailer hangs from the cable over the of the cliff. The jeep has a mass of 850 kg and pulls...
  13. U

    Free body diagrams with tension

    My question is for free body diagrams with tension on top and mass hanging from the bottom. Why is it "T-mg" sometimes and "mg-t" other times. How do I know which one to use? I was doing gravitation questions where "T-mg=Fc" sometimes and "mg-t=Fc" other times.
  14. A

    Free body diagram : Compression and Tension

    P, Q, R, S are light rods attached to the wall with a force W acting at that point in the figure. Please explain whether Compression or Tension is acting on them respectively by using Free body diagram and proper explanation. Can I resolve W in this way so that we have a force in the...
  15. C

    Solve Free Body Diagram: 2 Boxes, m1=35kg, m2=45kg

    Homework Statement Two boxes of masses m=35kg and m2=45kg, are hung vertically from opposite ends of a rope passing over a rigid horizontal metal rod. They system starts moving from rest. Assuming that friction between the rod and the rope is negligible, determine the magnitude of (a) the...
  16. L

    Including force in free body diagram

    Question The number of forces acting on a car parked on a hill(with parking brakes engaged) is Answers 1,2,3,4 When i drew the free body diagram, i got 4 but I am not sure if i should include a force
  17. V

    Drawing free body diagrams for pendulum

    Homework Statement I have to do this for a lab. Draw and label the free body diaggram of a pendulum when it is at its maximum amplitude of 30 degrees. The magnitudes of the vectors must be correctly scaled and the directions correct. Homework Equations The Attempt at a Solution...
  18. U

    Drawing a free body diagram on the mass

    Hi, I need some help with a question involving forces. I will appreciate greatly if someone can please have a look at this. Thanks. Question: A 2.00 kg mass, which is attached to a string of radius r, travels in a vertical circle. When the string makes an angle of \theta=52^o with the...
  19. J

    Learn How to Draw Free Body Diagrams for Various Physics Problems"

    how would u draw the free body diagrams for the following problems: 1. after a ball ball is hit: while it is in flight after leaving bat 2. pulling a fish out of the water accelerating it upward while it is in ari not water 3. as my car acelerates to the left, a pendant on a string...
  20. M

    Help Drawing Free Body Diagram

    I am trying to solve this problem but I am having a hard time drawing a free body diagram. Can someone please help me draw one so I can solve the problem http://img141.imageshack.us/img141/1662/untitled1pc1.jpg
  21. M

    Moments and free body diagrams help

    Hello all, Since I have run into the problem of regularly leaving moments out of my free body diagrams (and vice versa), I thought I'd pose a question on the topic. In trying to wrap my head around the concept, I've gone back to the beginning of the semester's notes and that didn't really...
  22. P

    Free Body Diagrams: All Forces Acting on Cart & Mass

    would this be all the forces acting on this cart and on the mass (minus friction of course)
  23. M

    Rigid Bodies and Free Body Diagrams (w pulley)

    Question: "A block of mass m1 = 1.87 kg and a block of mass m2 = 5.84 kg are connected by a massless string over a pulley in the shape of a solid disk having radius R = 0.180m and mass M = 12.7 kg. These blocks are allowed to move on a fixed block-wedge of angle 31.4 degrees as in the figure...
  24. D

    How Does Wind Affect the Forces on a Hanging Spider?

    a small spider weighing about 6.0e-3 N, hangs on its thread from the branch of a tree. A horizontal wind blows the spider and the thread to and angle of 35 degrees from the vertical. a)find the horizontal force of the wind on the spider b)find the tension in the thread i got a, here's wat...
  25. P

    Free body diagram friction homework

    while moving in, a new homeowner is pushing a box across the floor at a constant velocity. the coefficient of kinetic friction between the box and the floor is 0.41. the pushing force is directed downward at an angle beta below the horizontal. when beta is greater than a certain value, it is...
  26. F

    Draw free body diagrams for each sphere

    https://www.physicsforums.com/attachment.php?attachmentid=4225&stc=1 Determine the reaction forces at the four contact points A,B,C,D. The hollow balls which are homogenous and made of the same material have masses of 1.02kg and 2.04kg and the chamber they sit in is 55.98cm wide. Everything...
  27. C

    Why don't I get these free body diagrams?

    A man sits in a bosun's chair that dangles from a massless rope, which runs over a massless, frictionless pulley attached to the ceiling and back down to the man's hand. The combined mass of the man and chair is 90.0 kg. Ok, I found a solution that had T=Mchair*a + Fnormal + Mchair*g. How did...
  28. W

    What Forces Are Needed to Balance a Weldment on a Wall?

    Hello all, Can anyone provide the magnitude of the forces required to maintain a balanced condition within my attached free body diagram? I need to build a weldment and attach it to a wall. The weldment has a horizontal component that will carry a 750 pound vertical load placed 13 1/2"...
  29. J

    Master Free Body Diagrams: How to Draw Them for Different Scenarios

    Free Body Diagrams...help please! hello hello, i'm just having a bit of difficulty concerning free body diagrams: how would i draw an FBD for the following... a) an object has reached terminal velocity. would this mean that the object has reached a constant velocity, therefore force...
  30. P

    Master the Art of Free Body Diagrams: Understanding Vectors and Scalars

    When we do free body diagram, we usually consider the vector as scalar. I think this is a very important point, but why my teacher didn't clarify a lot?
  31. W

    Free body diagrams for forces on a block

    Hi all, For an online physics assignment I have a question about a block resting on a slope. The question asks what forces are acting on the block.. and I was thinking normal and weight force? But it turned out to be incorrect... list of possibilities to choose from weight kinetic...
  32. P

    Free body diagram Homework Problem

    Can someone please help with this problem. I'm lost! 1. A 150 kg bear walks out onto a beam as illustrated in Fig P8.20 trying to get to a picnic basket with mass 10kg. The beam is 6m long and has mass 40kg (you can consider its weight to be concentrated at a point 3m from the wall. (a)...
  33. J

    What is the Free Body Diagram for a Chain with Four Links?

    hello. I need help drawing free body diagram for four links on a chain. The picture looks like this: | <-thats a rope 8 <-these are links; they should all be connected 8 heres a good picture of a chain: http://homepage.mac.com/kpreid/povray/chain.png the first link is connected...
  34. S

    Solve Free Body Diagrams: What to Do?

    im having trouble solving this? what do i do with mew? thanks :cry:
  35. P

    Simple Free Body Diagram question

    I have a question in my textbook that I can't answer for the life of me. "A 6500-kg helicopter accelerates upward at .6 m/s^2 while lifting a 1200-kg car. (a) what is the lift force exerted by the air on the rotors?" Now, my diagram has a vector pointing up with a force of (6500*9.8)N...
  36. F

    Free body diagram for the block showing all the forces

    A block is held in place on a frictionless incline by a massless string. The string is horizontal. I have to sketch a free body diagram for the block showing all the forces exerted on the block.
  37. C

    Dynamics Problem HELP - Free body diagram

    IM in Phys.20 Got this question for an assignment. Tried it and got stuck. I really need help -------- When golfing, uphill and downhill putts present different levels of difficulty. Suppose a green has a 5.0 degree slope and the force of friction will be 0.10N...
  38. M

    Is my Free Body Diagram right?

    Howdy, I had Physics two years ago in High School and am now in Engineering Physics. I am trying to have a head start on everything and it is also a project, can anyone check my FDB for correctness? Thanks, Matt http://homepage.mac.com/jjacques2/fbd.gif
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