What is Atwood machine: Definition and 161 Discussions

The Atwood machine (or Atwood's machine) was invented in 1784 by the English mathematician George Atwood as a laboratory experiment to verify the mechanical laws of motion with constant acceleration. Atwood's machine is a common classroom demonstration used to illustrate principles of classical mechanics.
The ideal Atwood machine consists of two objects of mass m1 and m2, connected by an inextensible massless string over an ideal massless pulley.Both masses experience uniform acceleration. When m1 = m2, the machine is in neutral equilibrium regardless of the position of the weights.

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  1. Calpalned

    How Do You Calculate Acceleration in a Double Atwood Machine?

    Homework Statement The double Atwood machine shown in the figure has frictionless, mass-less pulleys and cords. Determine the acceleration of mA, mB, mC. Homework Equations F = ma The Attempt at a Solution...
  2. Calpalned

    Acceleration of a triple Atwood Machine

    Homework Statement http://photo1.ask.fm/723/921/945/-419996993-1shh761-9gamg0f647hgbk/original/IMG_4081.jpg There is no friction at all and this is a pulley system. The pulleys and string are mass-less. The numbers correspond to the block weight (ex: 3 = 3kg). Homework Equations F = ma...
  3. Poetria

    Atwood machine at rest and released

    Homework Statement In the image shown, two blocks hang on a pulley. Assume that m1 is the more massive block, and that the pulley is massless and frictionless. Take the initial case to be the instant just after m1 is released from rest, and the final case to be the instant just before m2 hits...
  4. J

    Example Problem in the book, why is tension ignored?

    Homework Statement An Atwood machine consists of two masses, M and m, which are connected by an inelastic cord of negligible mass that passes over a pulley. If the pulley has radius R and moment of inertia I about its axle, determine the acceleration of the masses M and m. Homework Equations...
  5. R

    Atwood Machine Lab: Graphing and Finding Moment of Inertia | Homework Help

    Homework Statement Good Morning, my teacher is making us redo this lab with data he collected. I was wondering if someone could check to see if I did it right so far. I have to graph the left side of equation B (in the spreadsheet) and the same for A. then I have to find the moment of inertia...
  6. O

    Changing masses on an atwood machine

    An example of this kind of a problem would be a frictionless, massless pulley holding two equal masses(say, 5kg each). But then, an additional mass is added to one side (ie, a frog jumping on to mass 1, 1 kg). What would happen to the system? What if the frog jumps off?Initially, I know that the...
  7. H

    How Do You Calculate Acceleration and Tension in a Double Atwood Machine?

    Homework Statement [/B] The double Atwood machine has frictionless, massless pulleys and cords. Determine the acceleration of masses mA,mB,mC, and the tensions in the cords.Homework Equations [/B] F=maThe Attempt at a Solution [/B] First I looked down the bottom section. Assuming mB> mA...
  8. T

    Atwood Machine Problem: Analyzing Friction & KE

    I'm actually grading this stuff, and have a question. Ideally there's no friction and no kinetic energy of pulley. If we take them into account, which one is more important? I wonder how to analyze this? Thanks a lot.
  9. S

    Need Help finding theoretical and actual acceleration (Atwood)

    So, I have an atwood machine lab. What I have been given is the masses of either end and time it takes the heavier mass to hit the ground from a distance. M1= .2kg M2 = .15kg avg time = 1.12 sec What i think I have to do: To find the actual acceleration I have to use v = vi + at and solve for...
  10. kq6up

    Lagrange EQ for a Double Atwood Machine

    Homework Statement 7.27 ** Consider a double Atwood machine constructed as follows: A mass 4m is suspended from a string that passes over a massless pulley on frictionless bearings. The other end of this string supports a second similar pulley, over which passes a second string supporting a...
  11. A

    What is the Force Exerted by the Ground on Object 1 in an Atwood Machine?

    1. A 77.00 Nt object (denoted as object 1) rests on the ground. A light cord is connected to this object which runs vertically upward over a light frictionless pulley and is attached to another object denoted as object 2. a) Calculate the force that the ground exerts on object 1 if object 2 is...
  12. G

    Atwood Machine pulley homework

    Homework Statement A pulley with mass Mp and a radius Rp is attached to the ceiling, in a gravity field of 9.81 m/s2 and rotates with no friction about its pivot. Mass M2 is larger than mass m1. The quantities Tn and g are magnitudes. 1) The magnitude of the acceleration of m1 is ...
  13. P

    Atwood machine with two ropes on one of the blocks

    Homework Statement Block 2 has a mass of 10kg and is attached to a pulley. The string going through the pulley is fixed to a bar on one end. The other end of the string goes over a pulley and a cylinder, of mass 20kg hangs on the string. The coefficient of friction between block 2 and the...
  14. T

    Atwood Machine: Acceleration of m1

    Homework Statement Three objects with masses m1 = 35.1 kg, m2 = 16.8 kg, and m3 = 10.5 kg are hanging from ropes that are redirected over pulleys. What is the acceleration of m1? Negative numbers for downward, and positive numbers for upward, please. Homework Equations F=ma...
  15. C

    Atwood machine with forces, not masses

    I am having difficulty reconciling this in my head. Imagine two Atwood machines (example). In both machines, the pulley is massless, there is no friction, but the rope is not massless, though it is inextensible. The rope and pulley in each machine are identical. The first is a traditional Atwood...
  16. U

    Lagrangian equation for 5 pulley Atwood Machine.

    Homework Statement Consider the Atwood’s pulley shown below. The masses are 4m, 3m, and m. Let x and y be the directed distances from the centers of the fixed (i.e. inertial) top pulleys for the left and right masses as indicated. http://imgur.com/VXEygxt a) Write down the Lagrangian...
  17. J

    Why Does the Atwood Machine Calculation Yield the Same Tension on Both Sides?

    Hello, I have a question about a sample problem in the McGraw Hill Physics 12 book. (p. 38-39). "An Atwood machine is made of two objects connected by a rope that runs over a pulley. The objects on the left (m1) has a mass of 8.5 and the object on the right (m2) has a mass of 17kg. a) What is...
  18. D

    Moment of inertia and Atwood Machine

    Homework Statement The question is from a lab. The lab used an Atwood Machine with two masses suspended string looped over a pulley. The time for one mass to reach the ground was measured and acceleration of the mass was calculated. The results were plotted on a graph of weight difference...
  19. C

    Archived Atwood Machine, I determining position of the masses.

    Homework Statement I know how to do this type of problem, I'm just confused as to how to determine the distance the (4m) mass goes up . Homework Equations N/A The Attempt at a Solution So I was thinking that if mass (5m) and mass (3m) go in opposite directions then mass (4m)...
  20. H

    Derivatives in an Atwood Machine

    Homework Statement I have the professor's solutions for a homework we handed in. There is a part that is confusing me. We have the following equation: $$E = \frac{1}{2}(m_1 + m_2)\dot{x}^2-(m_1-m_2)gx$$ Homework Equations We want to find: $$dE/dt = 0$$ The Attempt at a Solution...
  21. D

    Determining Scale Readings on an Atwood Machine

    Homework Statement Two masses, measuring 800g and 400g respectively, are attached to spring scales and an Atwood Machine. What will the reading of each scale be? https://www.physicsforums.com/attachments/52223 Homework Equations Fg = mg The Attempt at a Solution I think that...
  22. K

    Atwood Machine: Energy & Work Homework Soln

    Homework Statement An atwood machince has a m1 = 4.92-kg block resting on a frictionless horizontal ledge. This block is attached to a string that passes over a pulley, and the other end of the string is attached to a hanging m2 = 2.46-kg block. The pulley is a uniform disk of radius...
  23. A

    Atwood machine with two holes in pulley.

    Homework Statement A system consists of a pulley and two masses m1, m2 haning from it as shown in the figure. The pulley is a disk of radius R with constant mass density that has two circular hole with radius R/2. Find the angular acceleration of the pulley. Figure attached. Homework...
  24. P

    Modified Atwood Machine Problem

    Homework Statement Consider a modified Atwood machine, where one mass of 20 kg lies on a flat tabletop, and another mass of 5 kg hangs off the edge of the table, where the two masses are connected to each other by a massless string and a frictionless pulley on the edge of the table. The...
  25. D

    What is the acceleration of masses in an Atwood machine with a rotating pulley?

    Homework Statement I'm trying to find the acceleration of the masses in an atwood machine, the pulley has a rotational inertia I. The pulley has a radius R Picture : http://en.wikipedia.org/wiki/File:Atwood.svg But I made it accelerate the other way, so the equations from Newtons 2nd law are...
  26. D

    How does friction affect data in a modified Atwood machine?

    Homework Statement I have a modified atwood machine which is made up of a vertical mass hanger (hanging over the side of a table) connected to a horizontal cart (on the table) via a rope (un-stretchable) and a pulley (massless, frictionless, etc). The cart wheels have negligible friction...
  27. P

    How Do You Calculate Forces in a Modified Atwood Machine?

    1. I am trying to figure out the equation for tension force, friction force, acceleration, it looks from my very little physics knowledge is that it is based on the Atwood Machine, not the free hanging Pulley, but the pulley with the table (where one block is hanging, one is flat on the table)...
  28. G

    Swinging Atwood Machine, Hamilton-Jacobi Eq.

    This is a question about the swinging Atwood machine. I have completed the first half of the problems which involved finding a lagrangian involving the obvious co-ordinates, finding the conjugate momenta and writing a new Hamiltonian: H = E =...
  29. L

    Atwood Machine Problem and Newton's 2nd Law

    【Atwood Machine Problem】 Homework Statement Regular atwood machine lab where you test the proportionality of net force and acceleration as stated in Newton's 2nd Law. The regular lab procedure is to release the smaller mass at rest, to let it be lifted by the heavier one. Question is: "How...
  30. P

    Theoretical and Actual Acceleration for an Atwood Machine

    Homework Statement Include free body diagrams and equations solved independently for acceleration and tension. Note: a and T are to be expressed in terms of m1, m2, and g only. Trial 1:Mass1= 55g and Mass2= 60g Trial 2:Mass1= 55g and Mass2= 65g We are doing 2 trials but i need help with the...
  31. L

    Simplest Atwood machine question.

    Homework Statement Hi, the question is like in the picture. How hard should she pull the string to raise with constant speed? She weighs 70 kg together with the bucket. The Attempt at a Solution The system must have 0 acceleration, but does this mean she should pull the string with an...
  32. I

    Unequal Accelerations in Double Atwood Machine

    I have a simple question about the Double Atwood machine. I am able to follow the solution but one thing makes no sense to me. The accelerations for block A and block B are: Why aren't these equal? If they aren't, doesn't that mean the rope stretches? Or is this just an...
  33. J

    Double Atwood Machine Question

    Homework Statement I've tried and tried and can't solve this to look like this equation. Please Help! http://i233.photobucket.com/albums/ee237/biggyjoe210/IMAG0175.jpg 1. Show that the Acceleration of Mass A is given by : (look at picture) Homework Equations F = ma The...
  34. A

    How to Calculate Masses and Acceleration in an Atwood Machine Problem

    Atwood Machine Problem please help :) If one of the masses of an Atwood machine is 1.9 kg, what must be the other mass if the displacement of either mass is to be 0.1 m in the first second after release?
  35. S

    Free body diagram of atwood machine

    Homework Statement I need to find the forces on this modified atwood machine: http://imageshack.us/photo/my-images/36/atwood.jpg/ The Attempt at a Solution What I think: - On mass M there are two forces, Mg and -T. - On the mass above the spring there are two more forces, -2mg...
  36. S

    What is the maximum height reached by the 2kg mass in a modified Atwood machine?

    Homework Statement Two masses, 5kg and 2kg on the two ends of an atwood machine (ie. over a pulley). Initially, both are 0.6m above ground. Find the maximum height the 2kg mass will reach when the system is released. Homework Equations The Attempt at a Solution Maximum height...
  37. D

    Solving Atwood Machine: m1 & m2 Reaching Floor & Ascending Height

    Homework Statement One mass, m1 = 215g, of an ideal Atwood machine rests on the floor 1.10m below the other mass, m2 = 255g. (a) If the masses are released from rest, how long does it take m2 to reach the floor? (b) How high will mass m1 ascend from the floor? Known variables: m1 = 215g...
  38. G

    Atwood Machine + Torque - need a nudge

    Homework Statement Two weights, 75N (mass 1) & 125N (mass 2) are connected by a very light flexible cord that passes over a 70.0 N frictionless pulley of radius 0.200 m. The pulley is a solid uniform disk and is supported by a hook connected to the ceiling. What force does the ceiling exert...
  39. F

    Atwood machine rope tension problem

    Homework Statement Smaller mass on an Atwood machine is 5.2 kg (m1). If the mass accelerates at 4.6 m/s2what is the mass of the object? What is the tension of the rope? Homework Equations a = g(m2-m1)/(m2+m1) The Attempt at a Solution I can't approach this questions, because we...
  40. M

    Atwood Machine, weight of the string

    1. In the experiment(using a Atwood machine), should the mass of the string be added to the total mass moved by the unbalanced force for better accuracy? Explain. I think the answer is no because the weight of the string is very small and when doing the calculations to find acceleration, one...
  41. B

    Double Atwood Machine: relation between the contraints & the variables ?

    Double Atwood Machine: relation between the contraints & the variables ?! Hello. I am taking an analytical mechanics course & there's 2 "simple" equations relating the constraints to the variables. The problem is actually a class example. Here is it 1. The figure of the example is attached...
  42. N

    Atwood Machine Tensional Value Problem HELP

    1. A pulley with mass Mp and a radius Rp is attached to the ceiling, in a gravity field of 9.81 m/s^2 and rotates with no friction about its pivot. Mass M2 is larger than mass m1. The quantities Tn and g are magnitudes. A) T3 is ... T1 + T2 B) T1 is ... m1g. C) The C.M. of Mp+m1+M2 does not...
  43. M

    Potential Energy of Modified Atwood Machine

    Homework Statement The two weights on the left have equal masses m and ar connected by a massless spring of force constant k. The weight on the right has mass 2m, and the pulley is massless and frictionless. The coordinate x is the extension of the spring from its equilibrium length; that...
  44. D

    Atwood Machine, two masses + two pulleys (w/ mass)

    Homework Statement An Atwood machine is constructed using two wheels (with the masses concentrated at the rims). The left wheel (m1) has a mass of 2.1 kg and radius 21.44 cm. The right wheel (m2) has a mass of 2.8 kg and radius 33.94 cm. The hanging mass on the left (m3) is 1.53 kg and on...
  45. J

    Physics / Statistics question related to Atwood Machine and calculus of g

    Hello everyone. I am a 12th grade Portuguese student and have a theoretical question to pose, which is probably more related to maths & statistics. In our class, we made an experiment with an Atwood Machine and deduced the formula for the acceleration of the system (ignoring the string's...
  46. A

    Theoretical Acceleration of an Atwood machine

    Homework Statement The descending mass of the pulley system (atwood machine) is 60g and the ascending mass is 55g. Using DataStudio to measured the slope of the velocity over time (read by the spinning spokes of the pulley) the acceleration (constant) is experimentally given as 0.316m/s^2...
  47. V

    How Does Friction Affect the Timing in an Atwood Machine?

    Homework Statement It appears that the subscript is not working properly, please take m1 to means mass 1 and m2 to mean mass2 Atwood's machine consists of two masses connected by a string that passes over a pulley, as show in the figure. Consider the pulley to be massless and frictionless...
  48. M

    Calculating Mass of Atwood Machine to Keep It Still

    In the Atwood machine, what should M be, in terms of m1 and m2 so that it doesn't move? [PLAIN]http://img163.imageshack.us/img163/8288/atwood.jpg My work: It doesn't move, so I said T1=Mg (T1 is the tension in the rope attached to M), I believe the tension in the rope connecting m1 and m2 is...
  49. A

    Atwood Machine and the Work done

    The two block in an atwood machine have masses 2kg and 3kg. Find the work done by gravity during the fourth second after the system is released from rest.I have attached my attempt here..Kindly tell me where I went wrong. I am sure that I didnt go anywhere wrong in finding the acceleration and...
  50. U

    Atwood machine bounce, how high?

    Homework Statement Basically, an ideal Atwood machine is released from rest (m1 != m2) and I have to find out how high the mass, say m1, bounces after an absolutely inelastic collision with the floor (no energy is lost). Homework Equations Conservation of energy, Newtons equations...
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