# 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. ### Solving for Masses in an Atwood Machine

I've tried to solve this exercise but I haven't used one of the properties of the system (the displacement of the masses) so I don't know if I'm wrong about my procedure. First of all, we (obviously) know that $$P=P$$ And since we can express the power of a force in two different ways, we...

18. ### How Does the Speed of Block B Compare in a Three Mass Atwood Machine?

In the cable-pulley system shown here, block A is moving upwards at a speed of 5m/s and block C is moving downwards at a speed of 2.5m/s. What is the speed of block B? (See attached picture) This seems easy, I just want to make sure I'm not crazy. If mass B moves downward some distance d...
19. ### Atwood machine with variable mass

Homework Statement We have an Atwood machine like the picture below. one side (left) is a bucket full of water which has a hole on the bottom and the water is flowing with rate ##dm/dt = \alpha = const##. The initial mass of bucket with the water is ##m_0##. On the other side (right) we have a...
20. ### Half Atwood machine: acceleration after inital force

Homework Statement Assume that the block on the table (Figure 1) has twice the inertia of the hanging block. (a)You give the block on the table a push to the right so that it starts to move. If the magnitude of the frictional force exerted by the table on the block is half the magnitude of...
21. ### Is the block moving in an Atwood machine when climbing up a rope?

Homework Statement [/B] As stated in the included pics, you are climbing up a massless rope on a frictionless pulley, attached to a block equal to your mass which is hanging on the other side. You move a distance d along the rope. Does the block move? If so, how much? Homework Equations F =...
22. ### Potential Acceleration of an Atwood Machine

Homework Statement In the diagram, m1 has a mass of 47 kg and m2 has a mass of 35 kg. The coefficients of friction between m1 and the surface of the inclined plane are ยตs = 0.42 and ยตk = 0.19. (a) If the masses are held in place and then released, will they start to move? (b) If the answer...
23. ### Calculating Accelerations in an Atwood Machine with an Applied Force

Homework Statement The masses of blocks ##A## and ##B## are 20kg and 10 kg, respectively. The blocks are initially at rest on the floor and are connected by a massless and frictionless pulley. An upward force ##\vec{F}## is applied to the pulley. Find the accelerations ## \vec{a_A}## of block...
24. ### Kinetic energy of a compound system (atwood machine)

A system is defined as two connected masses in an atwood machine and the earth. How do I find total kinetic energy in a system where more than one object is moving (or is only one object actually moving since the two masses are connected with a string? idk) This is an isolated system so... ฮK...
25. ### Finding the decrease in potential energy of atwood machine

Homework Statement In the system below, m1<m2. When the object of mass m2 has descended a distance h, the potential energy of the system has decreased by: Homework Equations the answer is (m2-m1)gh The Attempt at a Solution I used ฮU= Uf-Ui m1gh-m2gh=ฮU (I think that the decrease in...
26. ### "Shifting" non-inertial frame in Accelerating Atwood Machine

Hello, I was referring to this thread: https://www.physicsforums.com/threads/accelerating-atwoods-machine-problem.44305/ to solve a problem on accelerating atwood machines in which, naturally, one attempts to find the acceleration of each of the individual masses. Although I now understand how...
27. ### Effects of Rolling Resistance on Tension and Acceleration in an Atwood Machine

We had a lab using an Atwood Machine with block A being on the surface and block B as the hanging object with different masses each round. Rolling resistance was present. Question 1 asked whether or not the tension in the string was less than, greater than or equal to the magnitude of the...
28. ### Double Atwood Machine Problem

Homework Statement If the masses for a double Atwood machine similar to the own shown in the attached picture are m1=2.0kg, m2=3.0kg, and m3=8.0kg: (a) what is the magnitude of the acceleration of the system and (b) how would you draw free-body diagrams for this problem? NOTE: m3 does not...
29. ### Infinite Atwood Machine (Morin Problem 3.3)

I could've peeked at the solution manual and end with it at that. However, I'm trying to change this nasty habit and solve this problem myself. I might be too ambitious. Here goes. Homework Statement Consider the infinite Atwood's machine shown. A string passes over each pulley, with one end...
30. ### What is the acceleration of the masses in a double double Atwood machine?

Homework Statement This is actually a problem I solved but I'm having trouble reconcile the answer with my intuition (Check the end of the post for my actual question). The problem: Find the acceleration of the masses for the double double Atwood machine (see figure) The masses are from left...
31. ### Velocity of masses on an atwood machine?

Homework Statement 2 masses m1 and m2 are attached by a string to a massless pulley. mass 1 is on the surface while mass 2 is hanging off. mass 1 experiences a friction force (mu)k. What is the acceleration of the system? What is the velocity of mass 1 in terms of mass 2? Homework Equations...
32. ### Atwood Machine: Find M in Terms of m1 & m2

Homework Statement In the Atwoodโs machine, what should M be, in terms of m1 and m2, so that it doesnโt move? Homework Equations F=ma The Attempt at a Solution I've set T1=Mg as T1 is the tension of the rope attached to M. m1 and m2 are both connected together by the same rope so I assumed...
33. ### Effective Friction Related to Pulley Radius (Atwood Machine)

First time posting on the forum - I've been coming here a lot the past year or so to seek answers. This one is concerning a lab. I think I've already done the legwork but am sort of looking for either something I'm missing or a confirmation of sorts. It's pretty messy and wordsy but if you...
34. ### I Intuitive Explanation of an Atwood Machine

So I'm working through a physics a textbook on my own, and because of that don't always have a professor who can help explain concepts I don't understand, so I'm turning to you good folks. Could someone explain why both masses need to be taken into account when determining the acceleration of...
35. ### Atwood's machine with two connected discs

Homework Statement The system looks like this: I have two discs which are connected. Disc 1 has ##R_1##(radius) and ##M_1##(mass) Disc 2 has ##R_2## and ##M_2## ## R_2 > R_1 ## ## M_2 > M_1 ## on both discs weights are attached on opposite sides. On smaller ##m_1## is pulling and on bigger...
36. ### Understanding the Motion of Double Pulleys: Exploring Acceleration and Forces

Homework Statement A mass m1 is hung on a pulley with another pulley on th eother side with two masses;m2 and m3.Find the accelerations of the masses Homework Equations F=M.a a1=-(a2+a3)/2 The Attempt at a Solution So in my book ,the solution provided was 2T-m1g=m1a1 T-m2g=m2a2 and T-m3g...
37. ### Coefficient of Friction of Fixed Atwood Pulley

Homework Statement Hi, I was wondering how you would isolate for and calculate the coefficient of friction in an Atwood pulley, with one fixed pulley, with two masses hanging off of it on either side. There is no table or surface that the masses are touching or resting on, they are both...
38. ### Is the Tension Force in an Atwood Machine Only Transmitted Between Blocks?

Homework Statement When talking about an Atwood machine, a student states: Is the student correct or incorrect? Why? Homework Equations Tension = mg + ma The Attempt at a Solution This is how it is making sense in my mind, but correct me if I'm wrong. I am thinking that the student is...
39. ### Double pulley Atwood machine (with 3 masses)

Homework Statement I need help with number 4. Also I am altogether unsure of this problem... if you catch any mistakes, point them out! :) Homework Equations F = ma Here are the variables I used in my attempt at the solution mx = m subscript 1, 2, or 3 ยฑa1 = acceleration of either mass on...
40. ### Negative Moment of Inertia from Atwood Machine Experiment?

I'm currently completing an Atwood Machine Experiment with two 100g weights on either side of the pulley, with a variance in weight created by attaching dimes and pennies to either side of the weights. The point of the experiment is to validate: (m1 โ m2)g = (m1 + m2 + I/R2) Homework Statement...
41. ### Atwood Machine, finding mass

Homework Statement atwood machine: pulley with negligible mass and frictionless with 2 blocks hanging at rest. The first block "m" has a mass of 3.66kg The second Block "M" is unknown The blocks are released; block M accelerates at .255*g m/s2 downward Find the mass of block "M" Hint: There...
42. ### Atwood Machine Lab Homework: Solve for Moment of Inertia

Homework Statement I am given the equation (m1 โ m2)g = (m1 + m2 + I/R2)a and the experiment is to validate this equation. Homework Equations The Attempt at a Solution After following the lab guide, it tells you to plot the weight difference (m1โ m2)g against acceleration and determine...
43. ### Tension force in Atwood machine

I've read a couple other threads about this issue. And one even addressed my exact question but the answer didn't help me understand this at all. In an Atwood machine, why isn't the total force on a mass = its gravity minus the gravity of the mass on the other side? I keep seeing tension in...
44. ### Atwood Machine Inertia Friction and directional forces

I have an Atwood Machine. I have an aluminium Pulley of radius 4 inch. A gym cable running over it. Not sure coefficient of friction but smooth movement. One end of rope, I attach wt. of 0.5 kg. I had to attach weight of 1 kg for acceleration to start. If I attach 2 kg, I had to attach 3.1 kg...
45. ### How to find mass in an Atwood machine

Homework Statement A pumpkin and a weight are attached to a frictionless pulley. As the 5kg weight is released, the pumpkin accelerates down at 4.65 m/s^2 to the ground. What is the mass of the pumpkin? [/B]Homework Equations How do I find the mass? The Attempt at a Solution T=m1g ma=m2g-T...
46. ### Half atwood machine with accelerating pulley

Homework Statement [/B] Consider a half-atwood machine on a cart as below, with mass m_2 attached to M via a frictionless track that keeps it pinned to M but allows it to move vertically. All surfaces (except between the wheels/ground) are frictionless, and the pulley and rope are massless. If...
47. ### The double Atwood machine has frictionless, massless pulleys

Homework Statement The double Atwood machine has frictionless, massless pulleys and cords. Determine (a) the acceleration of masses ma, mb, and mc, and (b) the tensions Fta and Ftc in the cords. Homework Equations F=ma The Attempt at a Solution So I drew free body diagrams for the mass A...
48. ### Atwood Machine, deriving equation for acceleration

Homework Statement I still don't got the hang on Atwood Machines, and i don't know if I am wrong here or just overthinking it. But i got this one exercise where i am kind of stuck in two of the sub-exercises. So I am hoping there is someone here who could guide me in the right direction.Atwood...
49. ### Faulty approach to solving a double Atwood's machine

Hello. I'm wondering why my approach to solving this problem (Morin 3.2) is faulty. Homework Statement A double Atwood's machine is shown, with masses ##m_1##, ##m_2##, and ##m_3##. Find the accelerations of the masses. Homework Equations ##F = ma## The Attempt at a Solution Let's say the...
50. ### Does Acceleration Affect the Stability of an Atwood Machine in an Elevator?

Homework Statement Please see attached for diagram. We know that the elevator arm is horizontal when the lift is stationary, with ## M_{1}=\frac{4M_{2}M_{3}}{(M_{2}+M_{3})}## It wants us to find out if this is still the case when the lift is accelerated upwards at a constant velocity ##g##...