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.

View More On Wikipedia.org
Recent contents Top users
  1. W

    Easy Free Body Diagram Question

    Homework Statement Draw the free body diagram of the system. (I know that's not what the problem is, but that's what I need clarity on) Homework EquationsThe Attempt at a Solution So I drew the same thing, more or less, but for mine Ay went up. This was how a very similar problem was done -...
  2. C

    Truss Free Body Diagram & initial conditions

    Homework Statement Complete a free body diagram for the truss structure with a weight attached to node 2 (this is known as 151N) Homework EquationsThe Attempt at a Solution I have attached my Free Body Diagram The diagram is to display what is know at the start of the problem before working...
  3. O

    Why is Block B not experiencing a normal force in this static friction problem?

    Homework Statement How come for the following image when I assume block B slips up, block A does not move. The free body diagram at block B does not have a normal from the ground. This is a static friction problem. [/B]Homework Equations No relevant equations all theory[/B] The Attempt at a...
  4. Racer_Rob

    Free body diagram for a sliding contact

    Homework Statement Component A is pushed vertically down with a known force F into component B. The angled surface of B is parallel to the angled surface of A. The contact between A and B is rough and so is the contact between B and the ground. The coefficients of friction are known and so is...
  5. J

    Help please -- Free body diagram for a weightlifter?

    Homework Statement A weightlifter stands up at constant speed from a squatting position while holding a heavy barbell across his shoulders. Draw the free body diagram of the lifer using Fg, normal force, and force by barbell Homework Equations Fnet=0 ? The Attempt at a Solution I tried...
  6. Mr Davis 97

    Representing Free body diagrams

    I have a simple question. I know that the objects that we work with in introductory physics are point particles. Thus, say we have a picture frame that is put on a wall. There is a wire holding it up, where the wire is attached to the top right and the top left corners of the frame. The passes...
  7. W

    Free body diagram of pin support and cable

    Homework Statement A) Draw a free body B) determine the tension in rope A and the reactions in B. Homework Equations [/B] Standard equilibrium equations The Attempt at a Solution My free body shows a collinear force T through the rope, the given downward force at 5ft, and then a Bx and By...
  8. W

    Setting up systems of forces and free body diagrams

    Homework Statement Suppose I've got a static mass on a downward plane. (For instance a car on a drive way). How would you set up this free body diagram? Homework Equations F = f1+f2...etc The Attempt at a Solution My preference is A, but I've seen it displayed in examples in my book as B...
  9. A

    Statics: four crates, four springs, free body diagram

    Homework Statement In figure (a), four identical crates weighing 2,000 lb each are stacked one on top of another, and in figure (b) a simple model for determining the deformation of the stack of crates is shown. In this model, each spring has the same stiffness k = 4,500 lb/in. and the forces...
  10. A

    Equilibrium of a Collar and Pulley System with Spring - Free Body Diagram

    Homework Statement A collar with a pulley slides on a frictionless vertical bar GH. A string A B C D is wrapped around, where portion AB of the string is horizontal. A spring with 2.5 lb/in. stiffness is placed between the collar and point H. The spring has 7 in. unstreched length and 5 in...
  11. K

    Classical Practicing Free Body Diagrams & improve problem solving skills

    Hi, I once considered myself enough to be decent enough to solve some problems but lately I'm thinking to revisit and start solving problems again. I would like to know whether there is a book good which has problems (starting from basic to tough ones) for practicing free body diagrams. The book...
  12. L

    Free body diagram drawing for a two force members on machine

    Homework Statement When a force of 2 lb is applied to the handles of the brad squeezer, it pulls in the smooth rod AB. Determine the force P exerted on each of the smooth brads at C and D Homework Equations ##\sum F_x=0## ##\sum M=0## ##\sum F_y=0## The Attempt at a Solution I drew a free...
  13. monsteruf

    Free body diagram for all forces

    Homework Statement Two ropes are connected to a steel cable that supports a hanging weight as shown in the figure. Draw a free-body diagram showing all of the forces acting at the knot that connects the two ropes to the steel cable. Draw the force vectors with their tails at the knot. The...
  14. E

    Free body diagram of a wheel driven by a motor

    Neglecting drag, I'm trying to understand how a wheel driven by a motor on a level surface rolls without sliding and experiences constant velocity. I'm trying to construct a free-body diagram. The wheel has a weight and a normal force acting on it in the vertical directions. The sum of...
  15. T

    What is the Sign Convention for Moments in Free Body Diagrams?

    Homework Statement In the picture, I am confused with the sign of the moments. When taking moments about D, the moment due to the 100N is taken as positive, but when they take moments about B, its negative. Homework EquationsThe Attempt at a Solution Shouldn't both cases be negative since in...
  16. D

    MHB Free Body Diagram Explained: Why is Right FBD Upward?

    Can you explain why the free body diagram of each members are as shown? I kind of understand why the FBD of the member on the left is drawn as shown. But the FBD on the right is confusing, Why does it have a component in Y (upward) direction? thanks!
  17. D

    (Vector statics) Effect of a pulley on free body diagram?

    For example, a 1-m bar fixed to a wall holding a weight of 100 N, like this: How will the free body diagram of the second case different from the first?
  18. K

    Free body diagrams and Newton's Law

    Homework Statement 2 masses, m1 and m2 are connected by a cord and placed on a frictionless table as shown in the diagram below. m1 slides on the frictionless table while m2 is hanging from a light frictionless pulley. What would be the mass of the hanging mass m2 if we know that the tension in...
  19. C

    Free Body Diagram of a ice skater?

    Homework Statement In our science class, we had to draw a free body diagram of an ice skater. The ice skater pushes against a force plate and that results in her skating in the other direction. (Newton's third law of motion). We have to use Newton's three law of motions to explain this...
  20. T

    Help with free body diagram for a pendulum

    Homework Statement I want to sum the forces perpendicular to the pendulum and sum the moments about the pendulums center of gravity. Homework EquationsThe Attempt at a Solution P\sin \theta - mg\cos \theta - N\cos \theta = -m\ddot x\cos \theta + ml\ddot \theta -Pl\sin \theta - Nl\cos \theta +...
  21. K

    Free body diagram of a beam construction

    Homework Statement Beams AC and BD are light (no mass) and they're conjoined at B. Points A and D are fixed but frictionless. The radius of the wheel is R and the weight hanging on the pulley has the mass m. Homework Equations Fx=0 Fy=0 M=0 The Attempt at a Solution I'm stuck at the very...
  22. nate crosby

    Free Body Diagram -- forces on a structure over a balcony wall

    Hi, I am trying to work out the forces involved at the contact points in a design of a structure over a balcony wall. I have drawn up the cross section of the situation equilibrium, with a tolerance. I want to find out what forces will be acting on the structure and the balcony wall when a...
  23. S

    What causes drag on a stationary car?

    See attached photographs. For the car problem, I think the drag should be smaller than the forward acceleration but I'm not sure. For the Rocket question, I am pretty sure I am correct but I'm not sure why. The drag and the weight would both be in the down position.
  24. G

    Free Body Diragram of a pulley

    Homework Statement In the figure (Figure 1) each of the suspended blocks has weight w. The pulleys are frictionless and the ropes have negligible weight. Homework Equations w = mg Forces cancel out, so Tension = weight (since they are suspended) The Attempt at a Solution For a (pulley) )...
  25. T

    Free Body Diagram of Car on Mountain

    If a car is on top of a mountain moving with an initial velocity, will it only forces acting on it be the normal force counteracted by the force due to gravity?
  26. hdp12

    Equilibrium of a Particle: Determining Forces in Cables and F for a 4-kg Lamp

    Homework Statement I am stuck on this problem for my mechanics class. Please help me. Determine the force in each cable and the force F needed to hold the 4-kg lamp in the position shown. Hint: First analyze the equilibrium at B; then, using the result for the force in BC, analyze the...
  27. M

    Resources for Practicing Drawing Free Body Diagrams

    I am absolutely clueless when it comes to drawing free body diagrams. I think I understand the concepts but as soon as I see an unfamiliar system I have no idea what goes where. Are there any resourcess that provide a large number of practice problems (with solutions) for drawing free body...
  28. M

    Help Drawing Free Body Diagrams?

    Homework Statement At a construction site, a small crane is raising two boxes of nails on a plank to the roof. One box has already been opened and is half full, while the other box is new. The boxes, including the nails, weigh 10kg and 20kg, respectively, and are both the same size. If the...
  29. U

    How Do You Balance Forces in a Bicycle Free Body Diagram?

    Homework Statement Bicycle with a rider applying weight to on pedal. Draw as free bodies in equilibrium. There are different situations. Homework Equations N/A The Attempt at a Solution So I am working on part a). 1. I believe it is only referring to just the pedal, chain, and the two...
  30. kiwimia

    Help on a free body diagram and equation

    1. Relevant information This is a two-block-system on top of each other to the right side of a wall, both attached with springs that are also attached to the wall. A force is applied on the bottom block to the right direction, frictions occurred on both bottoms of the two blocks. Here is the...
  31. S

    Free body diagram of an incline

    Homework Statement For the maximum angle for which you have data draw a free body diagram and explain how the forces add to give the resultant (net) force and show the calculations required to determine the acceleration. The lab was about using Galileo's inclined plane to measure acceleration...
  32. N

    Free body diagram and applying Newtons law

    hello! this is a question that iv been working on and can't seem to figure it out, i checked out the other two threads on this same question but they were of no help, anyway here it is: A wedge with mass M rests on a frictionless horizontal table top. A block with mass m is placed on the wedge...
  33. G

    How do I model the motor in this free body diagram problem?

    Hi I have a problem in understanding the attached free body diagram problem. I have a shaft that is pivoted at the top. Below the pivot is a magnetic bearing with a radial stiffness of 2600N/mm. I've modeled this as a springs in parallel. Below the bearing is a motor with a radial stiffness of...
  34. G

    Free Body Diagram Forces of a Rope Hoisting a Weight via Pillars

    So I am designing an apparatus to lift a 500g load up 500mm and I am trying to find reactions. I have filled in these values in my head with my own logic but I don't know how to do the maths and if I am right or not. I can do the initial position ok but it is the final position I am unsure of...
  35. C

    Free Body Diagram of a Truck with a Box

    Homework Statement A large box containing your new computer sits on the bed of your pickup truck. You are stopped at a red light. The light turns green and you stomp on the gas and the truck accelerates. To your horror, the box starts to slide toward the back of the truck. (Assume that the...
  36. P

    Help With Drawing a Free Body Diagram

    Homework Statement A large box containing your new computer sits on the bed of your pickup truck. You are stopped at a red light. The light turns green and you stomp on the gas and the truck accelerates. To your horror, the box starts to slide toward the back of the truck. (Assume that the...
  37. L

    MHB Free Body Diagram Solve Problem: Find Force Normal

    SOLVE THIS PROBLEM And this is the figure I need the free body diagram because the book solve this problem in this way the force normsl is n = fcosx the verticall componente is fsenx = w + miuN why does the fr is vertical in this case?
  38. Greg Bernhardt

    What Are the Rules for Drawing a Free Body Diagram?

    Definition/Summary A free-body diagram is a diagram of all the contact and non-contact forces acting directly on a body (in a non-inertial frame, that includes "fictitious" forces). Indirect forces (such as the weight of a different body), and internal forces, should not be shown...
  39. L

    Physics Fundamentals : Free Body Diagram

    Homework Statement A 5.0kg mass is suspended from the ceiling. A horizontal force F is applied to hold the string in position as shown http://i.imgur.com/ZdR72ff.jpg Determine the reading of F on the spring balance by using a scale diagram Homework Equations None The Attempt at...
  40. J

    A couple questions regarding force and free body diagram

    Hey guy, I would like to ask a few question about force and free body diagram. First question, I conduct a compressive experiment a few day back, using compression machine to test the strength of different materials e.g., Aluminium, PVC and Ceramic. However there is one thing that I don't...
  41. E

    Understanding Friction in Car and Trailer: Free Body Diagram Help

    Homework Statement http://postimg.org/image/vnn9m9au9/ For the car why is the friction acting towards the left. Shouldn't it be towards the right since the car is moving to the left And why is there no friction for the trailer? Homework Equations The Attempt at a Solution
  42. H

    Weight in an elevator? Free body diagrams

    A 60kg student is standing on a scale in an elevator that measures weight in Newtons. Calculate the reading on the scale if the elevator is accelerating down at 4 m/s^2...when the elevator is accelerating up at 4 m/s^2... and in free fall. Not sure if my work/answer is correct accelerating...
  43. P

    Free Body Diagram: Explaining 3 Cord Tensions for Block C

    Homework Statement http://postimg.org/image/5h0hvdi4l/ Can someone explain why the FBD of Block C would involve three cord tensions? Homework Equations The Attempt at a Solution
  44. samjohnny

    Free body diagram and force vectors

    Homework Statement Attached, where AC=BC=2R and CD=CE=3R. I need to work out the force the cylinder exerts on the cross section (in order to work out the moment at C). So first I'm trying to work out the free body diagrams for this system. Is it as I've attached? How do I draw the tension...
  45. T

    Free Body Diagram of a incline

    Homework Statement Draw a free body diagram of the incline. Build the free body diagram of the man. Which is the force which makes the man to go up the incline? http://imagizer.imageshack.us/v2/800x600q90/46/t92m.png Homework Equations Newton's 2º Law The Attempt at a Solution...
  46. C

    Can anyone help me check my free body diagram for mobile crane

    Homework Statement https://www.icloud.com/photostream/#AE5oqs3qHTNWQ;B21C49F3-02FB-4EA3-8CE5-D1E2C1FA7C49 Homework Equations The Attempt at a Solution https://www.icloud.com/photostream/#AE5oqs3qHTNWQ;A55D9431-FD6D-4884-9AFC-C4D7C8E39AF1
  47. P

    Discover How to Select Internal Forces for Free Body Diagrams

    Homework Statement http://postimg.org/image/4lvunjeoz/ Solution: http://postimg.org/image/v1d7gilef/ When you have to calculate the internal forces at a point, how do you decide which forces are included in the free body diagram? For D, why isn't the rectangular bit of the distributed load...
  48. P

    Solving Free Body Diagrams Homework

    Homework Statement http://postimg.org/image/i7phx5pp1/ Im trying to draw an FBD for this, but I don't know how the treat the distributed load or what forces the thing at E contributes. Is it some kind of support? For the distributed load, I don't know what part of it the 800N/m and...
  49. F

    Solving Free Body Diagrams with 1.9kg Object & F1=5, F2=2

    1. The question I'm struggling on has been answered on here before but with different values. Here is the link to the question https://www.physicsforums.com/showthread.php?t=344213 but on mine I have a 1.9kg object and F1=5 and F2=2. I figured out that the Y components are 0 for both of...
  50. marellasunny

    Free body diagram from whole system-direction of forces in free-body d

    Homework Statement A car and a trailer are connected by a joint. The car and trailer system are on a inclined place at a gradient of 8 degrees. The rolling friction coefficient along with other vehicle parameters are given.We are asked to draw the free body diagrams of the car and trailer...
Back
Top