Pulley Definition and 1000 Threads

A pulley is a wheel on an axle or shaft that is designed to support movement and change of direction of a taut cable or belt, or transfer of power between the shaft and cable or belt. In the case of a pulley supported by a frame or shell that does not transfer power to a shaft, but is used to guide the cable or exert a force, the supporting shell is called a block, and the pulley may be called a sheave.
A pulley may have a groove or grooves between flanges around its circumference to locate the cable or belt. The drive element of a pulley system can be a rope, cable, belt, or chain.
The earliest evidence of pulleys dates back to Ancient Egypt in the Twelfth Dynasty (1991-1802 BCE) and Mesopotamia in the early 2nd millennium BCE. In Roman Egypt, Hero of Alexandria (c. 10-70 CE) identified the pulley as one of six simple machines used to lift weights. Pulleys are assembled to form a block and tackle in order to provide mechanical advantage to apply large forces. Pulleys are also assembled as part of belt and chain drives in order to transmit power from one rotating shaft to another. Plutarch's Parallel Lives recounts a scene where Archimedes proved the effectiveness of compound pulleys and the block-and-tackle system by using one to pull a fully laden ship towards him as if it was gliding through water.

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  1. A

    Normal force of real pulley: Which direction is it?

    Consider a pulley fixed to the ceiling. A mass-less string is wrapped around it, with each side of the string hanging down either side of the pulley. Since the pulley has friction with the string, tension along the string will vary. Let's say the string is attempting to move clockwise, so the...
  2. D

    Finding acceleration with ideal pulley

    Homework Statement Two blocks are connected by a string as in the figure. (below) What is the upper block's acceleration if the coefficient of kinetic friction between the block and the table is 0.18? Express your answer to two significant figures and include the appropriate units. Homework...
  3. D

    Two stacked boxes and a pulley with a weight attached

    Homework Statement The system shown is released from rest. Mass one (0.450 kg) rests on mass two (0.820 kg) and the coefficient of static friction between the two masses is 0.560 and the same for the mass and the table. Determine the maximum mass for M3 such that the mass one will not slide on...
  4. A

    Conservation of energy: mass-spring system

    1. A 1 kg block is on a flat frictionless surface. Attached to a relaxed spring (k=50N/m). A light string is attached to the block and runs over a frictionleas pulley to a .45kg dangling mass. If the dangling mass is released from rest, how far will if fall before stopping? Homework Equations...
  5. NATURE.M

    Unraveling a Complex Pulley System: Finding Accelerations of Two Attached Masses

    Homework Statement Note this problem is from Morin 3.28. The atwood machine has two masses, m. The axle of the bottom pulley has two string ends attached to it, as shown. Find the accelerations of the masses. A small diagram is attached below. Note, at the two loose ends of string, there is...
  6. J

    Two Blocks and a pulley (Equation derivation)

    Homework Statement Look at the figure below. Derive the formula for the magnitude of the force F exerted on the large block (mC) in the figure such that the mass mA does not move relative to mC. Ignore all friction. Assume mB does not make contact with mC. Homework Equations F = ma...
  7. T

    Pulley Equations: Learn How to Calculate Lifting Power

    Hello, Im looking to pay around with some pulley equations amount distance and angles and how they alter the pulley lifting power, if anyone could post them or point me in the write direction
  8. END

    Mechanics: Acceleration in Pulley System

    1. The problem A 3.0-kg block sits on top of a 5.0-kg block which is on a horizontal surface. The 5.0-kg block is pulled to the right with a force ##\overrightarrow{F}## shown in the figure. The coefficient of static friction between all surfaces is 0.65 and the kinetic coefficient is 0.37. If...
  9. Z

    Statics/Equilibrium Physics question-- Two weights and a single pulley

    Homework Statement The 60 lb collar "A" is on a friction-less vertical rod and is connect to a 65 lb counterweight "C". Determine the value "h" (which is the height between "A" and "B") for which the system is in equilibrium. Also, find the horizontal force "N" acting on collar "A". Here is a...
  10. A

    Help Midterm tomorrow Pulley, Newton's Laws Problem

    1. Homework Statement An object consists of 3 connected masses as seen in the figure. None of the surfaces have friction except the surface on m1 which has the coefficients μs=0.4 y μk=0.3. What is the acceleration of each one of the masses? It looks like the following image but m1 is the...
  11. A

    Newton's 3rd Law, pulley, only given friction coefficients

    Homework Statement An object consists of 3 connected masses as seen in the figure. None of the surfaces have friction except the surface on m1 which has the coefficients μs=0.4 y μk=0.3. What is the acceleration of each one of the masses? It looks like the following image but m1 is the table...
  12. C

    What is the tension in the rope used to pull two blocks with friction?

    Homework Statement Mass Ma lies on top of mass Mb, as shown. Assume Mb > Ma. The two blocks are pulled from rest by a massless rope passing over a pulley. The pulley is accelerated at rate A. Block Mb slides on the table without friction, but there is a constant friction force f between Ma and...
  13. S

    Variable pulley distance - tensioner force help needed

    Greetings, lurked for a long time, but I need some help here so I joined up. Please have some patience with me if I miss any important information. I am working on a belted pulley drive system where the driveN pulley will move relative to the driveR while in the stopped state. An outside...
  14. J

    Calculate Motor Torque for Running 8 Pulleys off One Motor

    I would like to run 8 pulleys off of one motor. Each "pulley" would be 19" in diameter with 20lb of weight at 30RPM. I would like to know how to calculate the inch-lb that would be required of the motor. I read this on masterdrives.com Torque(inch-lb) = (.03908 x N x W x R^2)/t Where N...
  15. K

    Angular acceleration of pulley with two masses

    1. Homework Statement The system shown in the diagram contains two blocks, of masses 1.9 kg and 5.7 kg, connected by a light string over a pulley of radius 0.15 m and rotational inertia 2.8 kg m 2 . The block of mass 5.7 kg is free to slide on a horizontal frictionless surface and the pulley is...
  16. matineesuxxx

    Work-Energy Principle: Pulley System

    Homework Statement (see attatchment) We know masses M and m, and I am trying to describe the downward speed of m in terms of the hight from the ground. There is no friction Homework Equations \sum \text{F} = ma W_{\text{total}} = \Delta K = \int \text{F} \cdot d\text{s} The Attempt at...
  17. BrainMan

    Torque and angular acceleration pulley problem

    Homework Statement A pulley in the shape of a cylinder of mass 5 kg and radius 0.6 m has a force of magnitude 30 N exerted tangentially on it. Find the angular acceleration of the pulley and its angular velocity after 3 s, assuming it starts from rest. Homework Equations T = Ftr T = mr^2a...
  18. P

    Solving Pulley on a Pulley Problem using Force Analysis

    I'm currently reading Kleppner and Kolenkow's "Introduction to Mechanics", and I'm working through the problem sets. I'm only on chapter 2, but I happen to know Lagrangian mechanics. When I get stuck on a problem I occasionally take the Lagrangian approach to find the solution, and then I try...
  19. T

    What is the Tension in Block m2's String in a Pulley System?

    Homework Statement The diagram shows a system of two blocks suspended by ideal strings and pulleys. If the tension of the string attached to block m1 is T, what is the tension of the string attached to block m2?Homework Equations Due to conservation of string, a1/2 = a2 Force balance on mass...
  20. S

    Spring - Pulley - Mass <Oscilations problem>

    We have a mass M attached to a string. In the other extreme of the string we have a spring. We know the moment of inertia of the alloy I, and it's radius R. We know the constant of the spring k. The string is inextensible. String mass is negligible. There's not friction. There's no slipping...
  21. N

    What Is the Acceleration of Block A and the Tension in the Cord?

    Homework Statement Block A has a weight of 400N and block B has a weight of 100N. The coefficient of friction between all surfaces of contact are μs = 0.7 and μk = 0.2. Knowing that θ = 60°, determine the acceleration of block A and the tension in the cord. Assume block A is moving downwards...
  22. I

    Two Pulley Problem: Solve & Find Correct Answer

    Tried the problem but answer is not matching with the given answer. Can you tell me what is the correct answer and how you got it? (problem is attached as image)
  23. J

    Blocks and pulley with mass - rotational dynamics

    Homework Statement Two blocks of masses m1 = 8.00 kg and m2 = 12.00 kg are connected by a string of insignificant mass. The string lies on a cylinder of mass 0.50 kg and a radius of 0.15 m. The coefficient of kinetic friction between m1 and the surface of an inclined plane is 0.10. The angle...
  24. G

    How Well Do You Understand Atwood Machine Pulleys?

    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 ...
  25. A

    2 masses suspended over a pulley, finding a mistake

    Homework Statement http://i.imgur.com/1j19V0n.jpg Two masses are suspended from a pulley as on the pic. I have pulleys radius R and moment of inertia I and masses m1 m2. Homework Equations The Attempt at a Solution So 2nd law of motion: N_{1} - m_{1}g=m_{1}a m_{2}g-N_{2}...
  26. STEMucator

    Troubleshooting a FBD of a Pulley

    Homework Statement I'm having a bit of trouble understanding something from this: http://gyazo.com/88a466b57d8516d2df1b12008947be43 Homework Equations The Attempt at a Solution I understand how to get the components of reaction at ##A## as well as the tension in segment...
  27. G

    How Is Acceleration Calculated in a Basic Table Pulley System?

    Homework Statement Mass m1 = 14.9 kg is on a horizontal surface. Mass m2 = 7.48 kg hangs freely on a rope which is attached to the first mass. The coefficient of static friction between m1 and the horizontal surface is μs = 0.571, while the coefficient of kinetic friction is μk = 0.105. If the...
  28. B

    Return of the Inclined Plane Double Pulley: Part II: Energy

    Homework Statement My last inclined plane problem has a second part to it: There are some energy problems I need to solve. A double pulley consists of two separate pieces that are welded together; a hoop of radius 10.0 cm and a disk of radius 15.0 cm. The moment of inertia of the pulley is...
  29. B

    Inclined Plane Double Pulley Problem

    Homework Statement A double pulley consists of two separate pieces that are welded together; a hoop of radius 10.0 cm and a disk of radius 25.0 cm. The moment of inertia of the pulley is 0.160 kg-m^2. A 15.0 kg block (m1), on a 35.0° incline, is attached to the outer pulley by a massless...
  30. C

    How Do Pulley Systems Affect the Force Needed to Lift Weights?

    I am having trouble understanding the distribution of forces present within a pulley system; namely, how the number of sections of rope that supports an item manages to decrease the force necessary to move it. For example, look at this picture I am aware that system A only requires 5...
  31. M

    Atwood pulley and calculating inertia based on slope (m)

    I am working on a lab that is meant to test the validity of (m1
  32. RaikkoBoy7

    Solve Step Pulley System Homework: Acceleration Relation

    Homework Statement A step Pulley system is shown in the figure.The string and Pulley are of Negligible Mass.The relation Between the acceleration of Block and Block will be what then ?I am having troubles in approaching this question! Homework Equations The Attempt at a Solution
  33. C

    What is the Lagrangian of a Pulley System with a Uniform Chain?

    Homework Statement A uniform flexible chain of mass M and length L is hung under gravity over a frictionless pulley of radius a and moment of inertia I whose axle is at a fixed height above the ground. Write down the Lagrangian of this system in terms of a generalized coordinate l denoting the...
  34. A

    How Does Conservation of Energy Determine the Final Velocity in a Pulley System?

    Homework Statement Use conservation of energy to find the final velocity of m1. m1=0.05kg m2=0.02kg m3=0.5kg r=16cm h=2m Homework Equations Kinetic Energy=1/2m*v2 Rotational Kinetic Energy=1/2I*ω2 Gravitational Potential Energy=mgh The Attempt at a Solution 0=(1/2m1v2) +...
  35. D

    Mass and pulley system question

    Homework Statement A mass M = 53 g hangs from a light, inextensible string. It passes without sliding over a pulley. The pulley can be treated as a solid homogeneous disc with mass mp = 12 g and radius 3.6 cm, that turns without friction on its axis. The other end is attached to a mass m =...
  36. R

    Pulley & Angle: Tension Calculation

    Hello everybody Im trying to calculate the tension in wire (se attached image). the wire is wrapped around a pulley and combined in the end at which you pull with 50 kN. As far as I understand, if youdon´t have this angle so that that the wire ends follow the red dotted line then one can just...
  37. D

    Massive Pulley Dilemma: How to Account for Acceleration?

    Hi all: I am studying the mechanics of a system where there is string wrapped around a massive pulley, and a block at the end of the string. Correct me if any of this is wrong, but the system (pulley and block) must have the same linear acceleration. So, in the case that the pulley is...
  38. R

    Tension in the string of a rotating, massive pulley

    Homework Statement Hi, everyone. Me again. This time I'm here to ask about the tension in the string on a massive pulley. We have a wheel of radius R with a moment of inertia about its principal axis of 2/3 MR2 , suspended above the ground on frictionless bearings. A massless string of...
  39. B

    How do mass affect the acceleration of a pulley?

    Hi, i am doing physics 20 and i am still quite new at this stuff. I have a base understanding of how the mass affect the acceleration but i can't find a way to explanation of why the the mass affects the acceleration by making it faster or slower of a pulley for my lab like this one...
  40. B

    Pulley with 2 Blocks on an Inclined Plane. Help please

    Homework Statement I've been stuck on this problem for hours now. I know it has to be somewhat simple, but I am not too great in physics, so I am asking for help on how to complete this problem. Two blocks are positioned on surfaces, each inclined at the same angle 50 degrees with respect...
  41. N

    Ratio of work done using pulley

    Homework Statement As you are trying to move a heavy box of mass m, you realize that it is too heavy for you to lift by yourself. There is no one around to help, so you attach an ideal pulley to the box and a massless rope to the ceiling, which you wrap around the pulley. You pull up on the...
  42. N

    Equal tension on rope in a pulley system?

    Suppose the rope involved in the pulley is massless and experience no friction. Why is the force on the right hand side equal to the tension experienced by the rope on the left hand side?
  43. M

    Acceleration on a pulley system with 3 blocks

    Homework Statement Three objects are connected on an inclined table. The objects have masses 8.0 kg, 4.0 kg and 2.0 kg as shown, and the pulleys are frictionless. The tabletop is rough, with a coefficient of kinetic friction of 0.47, and makes an angle of 20.0° with the horizontal. The 8.0kg...
  44. A

    A pulley system with two objects stacked on each other

    Homework Statement Block B, with mass 5.00kg, rests on block A, with mass 8.00kg , which in turn is on a horizontal tabletop. There is no friction between block A and the tabletop, but the coefficient of static friction between block A and block B is 0.750. A light string attached to block A...
  45. F

    Find Mass of Object 2 in Two-Mass Pulley System

    Homework Statement Two masses are attached by a light string and looped over two frictionless pulleys. Object 1 (200g) accelerates upwards at a rate of 4.90 m/s squared. Determine mass of object 2. Homework EquationsThe Attempt at a Solution I tries doing this but don't think its right...
  46. K

    Block-on-Block attached by String to Block in Pulley on Incline

    Hi all, The problem is shown below - but no answer was given to this, and the teacher did not plan on taking it up, since it was optional extra practice. My attempt at a solution: http://imgur.com/DmrgMMO, my final answer was 2.76 kg. I was wondering if this was right or wrong, and if...
  47. A

    How Much Can Block A Weigh Without Block C Slipping Off?

    Problem: Block A is suspended from a vertical string. The string passes over a pulley and is attached to block B. The mass of block B is 1.8 kg. The mass of block C is 0.75 kg. If the coefficient of kinetic friction is 0.100 between block B and the ramp and the coefficient of static friction...
  48. D

    How Is Acceleration Calculated in a Pulley System with Unequal Masses?

    Homework Statement Two particles of masses m and 2m lie together on a smooth horizontal table. A string which joins them hangs over the edge and supports a pulley carrying a mass 3m. prove that the acceleration of the latter mass is 9g/17 Homework Equations f=m1g/m1+m2 The Attempt...
  49. T

    Find the Value of θ in a Pulley Blocks Problem - Homework Solution

    Homework Statement Q. In the figure shown, find out the value of θ [ assume string to be tight ] Homework Equations The Attempt at a Solution If the pulley was not moving ,then we could have equated the component of velocities of the two blocks along the string . But,since...
  50. Rugile

    What is the solution for the Pulley System Problem?

    Homework Statement No friction, pulleys and also string are weightless, the tension through the string is distributed uniformly. Find the acceleration of the mass 3M (see image attached) Homework Equations II law of Newton The Attempt at a Solution Well I wrote such equations for...
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