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. C

    Constrained motion with movable pulley

    Homework Statement In this, if I want the acceleration constraint between M and 2M, I write $$AM+2AB$$=LENGTH OF STRING, which on differentiating twice gives $$a_{m}=2a_{2m}$$(which turns out to be correct). However, if we look closely, the, lower end of string is FIXED to the pulley A, and...
  2. AHashemi

    Pulley attached to a pulley - Find the balance equation

    Homework Statement A string is hung over a fixed pulley, and a mass of m3 is suspended from one end of the string. The other end of the string supports a massless pulley, over which a second string is hung. This string has a m2 mass attached to one end, and a m1 mass attached to the other end...
  3. CentrifugalKing

    Need a bit of help -- Pulley accelerated by a force....

    Homework Statement A pulley, with a rotational inertia of 1.5✕ 10-3kg·m2 about its axle and a radius of 10 cm, is acted on by a force applied tangentially at its rim. The force magnitude varies in time as F = 0.50t + 0.30t2, where F is in Newtons and t in seconds. The pulley is initially at...
  4. C

    Velocity of boat connected by a pulley fixed at some height

    Homework Statement A pulley fixed on a wall of height h connects a toy boat with a man on the wall. The string is pulled by the man at a constant speed u m/s. Find the velocity of boat when the string makes an angle $$\theta$$ with the water. Homework Equations The question will be more...
  5. AliGh

    Pulley on a moving base problem

    Hi today the teacher showed us analyzing forces in a system he showed them on easy problems But at the end of the class he gave us this question to solve Its not homework because its way beyond what he taught The base moves without friction on surface So i want to find a3 and theta and a of 2...
  6. K

    Determining velocity for a pulley/rope system

    The Question: Using a simply pulley/rope system, a crewman on an Arctic expedition is trying to lower a 5.65-kg crate to the bottom of a steep ravine of height 23.9 meters. The 60.9-kg crewman is walking along holding the rope, being careful to lower the crate at a constant speed of 1.50 m/s...
  7. B

    Dynamics - Pulley System with Rotating Rod

    Homework Statement At the instant shown, the rod R is rotating about its centre of rotation with ω=3.8rad/s. mA=10kg; The pulley, with mP=8.7kg and RP=0.2m, may be modeled as a uniform disc. The rod, with mR=4.1kg and L=0.8m, may be modeled as a thin beam rotating about one end. g=9.8m/s ²...
  8. J

    Two blocks on a plane with a pulley

    Homework Statement A block of mass m1 = 3.70 kg on a frictionless inclined plane of angle 30.0° is connected by a cord over a massless, frictionless pulley to a second block of mass m2= 2.30 kg hanging vertically. What are (a) the magnitude of the acceleration of each block and (b) the...
  9. T

    Ratio of two masses connected by pulley

    Homework Statement [/B] Figure 1) Block 1, of mass m1, is connected over an ideal (massless and frictionless) pulley to block 2, of mass m2, as shown. Assume that the blocks accelerate as shown with an acceleration of magnitude a and that the coefficient of kinetic friction between block 2 and...
  10. mia_material_x1

    How Much Work is Done Raising a Load with a Two-Pulley System?

    Homework Statement A 60 kg load is raised by a two-pulley arrangement. How much work is done by the force F to raise the load 3 m if there is a frictional force of 20 N in each pulley? Note that the pulleys do not rotate, but the rope slides across each surface. I've solved the problem, I...
  11. U

    Pulley system w/hanging mass, two unknown masses and Mk

    Homework Statement A mass m1 on a horizontal shelf is attached by a thin string that passes over a frictionless pulley to a 2.4 kg mass (m2) that hangs over the side of the shelf 1.4 m above the ground. The system is released from rest at t = 0 and the 2.4 kg mass strikes the ground at t = 0.85...
  12. T

    Acceleration on a Pulley: Equal or Different for Connected Masses?

    Homework Statement We are dealing with a frictionless table with one mass on the table, while the other one hangs over the edge on a pulley connected by a string... and the mass on the table is greater than the mass hanging from the edge... When the blocks are released from their resting...
  13. L

    Acceleration and Tension in Multiple Pulleys

    Homework Statement Block "m1" sits on a horizontal frictionless surface. Block "m2" is hanging below the pulleys as shown. All of the pulleys are massless and frictionless. Given [m1, m2]. Determine: a. The tension in each rope. b. The acceleration of each block. Homework Equations Sum(F) =...
  14. K

    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...
  15. L

    Pulley problem with 2 masses and an incline

    1. A mass on a flat surface is pulled with an angled force of 200N (as shown) and is connected by a massless rope/pulley to another mass below on an incline. Find the acceleration and Tension in the rope.Homework Equations Fnet = ma Fg = mg Ff = Mu x Fn The Attempt at a Solution Had a question...
  16. Thornak

    Force With a Pulley: Theoretical and Experimental

    Homework Statement [/B] This is not a typical homework problem, so I hope I am posting this in the correct place. I am in 12th grade physics and we are dealing with basic kinematics. However, we recently did a set of problems that I did in a way which makes sense and which our textbook (and the...
  17. J

    Struggling to Understand Pulley System Dynamics

    Homework Statement it is Problem 3.30. Homework Equations I am not sure how to sum the forces about each consecutive pulley I have been at this for 4 hours now. It is sad I can solve the DE questions and not this. The Attempt at a Solution I had the first pulley at the top as (where y is...
  18. Skilen

    A man hangs from a hole, Horizontal pulley

    I 1. A man of mass m = 80.0 kg hangs from a rope down into a hole. The rope goes over a massless pulley and is connected to a block of rock of mass M = 200 kg, which is lying on a frictionless horizontal surface. The distance between pulley and man is 5.00 m; between pulley and block 20.0 m...
  19. Jonski

    Reaction Force, find tension, a in the tangential, or alpha

    Homework Statement The diagram shows the instant when a long slender bar of mass 4.9 kg and length 4.9 m is horizontal. At this instant the mass m= 6.5 kg has a vertical velocity of 4.0 m/s. If the pulley has negligible mass and all friction effects may be ignored, what is the magnitude of the...
  20. P

    Tensions with 3 blocks on a single pulley

    Homework Statement The diagram shows two blocks, each of mass m, connected by cord A, and the top block of mass m connected to the block of mass M by cord B. Both cords are of negligible mass. Cord B passes over a frictionless peg that is fixed in place. The system of blocks and cords is...
  21. A

    Pulleys - Relationship between mass and aceleration

    1. Homework Statement 2. Homework Equations How to get ax=2ay? 3. The Attempt at a Solution a=10m/s2 And the solution I found was a=2m/s2 I found this at : http://www.physicstutorials.org/home/exams/dynamics-exams/142-dynamics-exam1
  22. 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...
  23. A

    Forces acting on a pulley question

    Homework Statement Student 1 (50-kg), sits on a chair with metal runners, at rest. Student 2 (85-kg), sits on an identical chair. Both students keep their feet off the floor. A rope runs from student 1's hands around a light pulley and then over her shoulder to the hands of a teacher standing...
  24. O

    Easy statics problem -- Block being hoisted by a pulley and rope

    I drew a FBD about point A and came up with the two equations: ∑Fx=0 20sinθ - T-ab(cos70)=0 ΣFy =0 -20cosθ + T-ab(sin70) -20=0 My answer is not coming out so I either messed up on the FBD or the equations, some help would be appreciated. I'm on 3-10 by the way.
  25. E

    Using a bimetallic coil to turn a pulley

    Hello, I am looking at the possibility of turning a pulley using a bimetallic coil embedded inside. How can I calculate the thermal "spring constant" of the coil, as a function of geometry and material properties? Does anyone know of devices with similar actuation mechanisms? thank you.
  26. Crimpchimp

    Calculating the force acting on a pulley in a hoist system

    In the diagram below there is a hoisting system set up to lift a 1000 lb. unit up a radio tower. This unit is used for painting towers and is lifted using a capstan hoist. As the unit is lifted, it will be tagged with a 6ft. (adjustable) tag line with a pulley that travels up the end of the...
  27. K

    Could we throw stuff into space?

    hello everyone. just wondering with development in modular robotics, could we possibly throw a space station into space bit by bit via something as simple as a pulley system? doing a bit of research i found out you can get a 1000 ton crane, therefore 9,800,000N of force, i also found out that...
  28. L

    Virtual Work in a Pulley System

    Homework Statement The system shown in Fig. 2-6 is in static equilibrium. Use the principle of virtual work to find the weights A and B. Neglect the weight of the strings and the friction in the pulleys. Quick aside: This is straight out of the Exercises for the Feynman Lectures on Physics, in...
  29. oreo

    Is the Pulley Reacting to Tension in Lifting Rope?

    Suppose a pulley is lifting a mass through rope so the rope is applying force to mass in form of Tension. Is the rope also applying that force to pulley i.e Is pulley being acted upon by Tension??
  30. C

    Mechanical advantage of a mountain climber (pulley)

    Hi I have a hard time undersanding the mechanical advantage of this pulley system (in the video below): I understand that when a person is holding you, then the mechanical advantage is 2, because 50% of the weight or Load is on the rope going from the harness to the top left anchor point, and...
  31. W

    Calculation of Cable tension through pulley system

    Hi, I'm new to PF so this is my first post. I have a real case scenario as my first thread in which I have a gravitational tensioning system that provides tension to a cable conveyor. The tensioning system includes a series of pulleys in a particular reeving arrangement that is fixed on one...
  32. K

    Pulley project of mine requiring help

    text is same as on pic. I'm trying to express this diagram as algebraically as possible so later on I can add real world limitations into my equation and see what other requirements are needed. I got the first and simplest one which is to be in equilibrium the mass/weight of B has to be...
  33. S

    How to find shaft torque for belt pulley arragement?

    I am facing problem in calculating the shaft torque for my system. Motor is driving pulley and that pulley is coupled with belt with another big pulley (please refer attached file image). Motor power 19.4 kw, Torque- 71.8 Nm, Motor Rated speed- 2580 rpm, motor shaft dia=42mm Pulley dia (refer...
  34. K

    Pulley question -- 2 pulleys and 2 weights

    THIS THREAD WAS INCORRECTLY PLACED IN THE CLASSICAL PHYSICS FORUM, SO THERE IS NO TEMPLATE Hi, everyone. my teacher stuck me with these questions and i am need of a little help answering question 2. here's my answers to question 1 first. 1a) a=0, as system would be in equilibrium when F=0 b)...
  35. J-dizzal

    Static equilibrium problem -- with a pulley

    Homework Statement Homework Equations sum of forces equal to zero. The Attempt at a Solution
  36. D

    Calculating Work and Kinetic Energy in a Two Mass Pulley System

    Homework Statement https://int.erlace.com/uploads/teacher/1533/images/3modifiedatwood(1).jpg Ignore friction and the the rope and the pulley and the rope have negligible mass. When the hanging block has descended a distance , how much work has the gravitational force by the Earth done on...
  37. J-dizzal

    Pulley problem, acceleration, angular velocity, inertia

    Homework Statement In the figure, block 1 has mass m1 = 450 g, block 2 has mass m2 = 530 g, and the pulley is on a frictionless horizontal axle and has radius R = 5.3 cm. When released from rest, block 2 falls 71 cm in 5.0 s without the cord slipping on the pulley. (a) What is the magnitude of...
  38. O

    Pulley -- Solving for an unknown mass

    Homework Statement If I have a mass attached to each side of an atwood's machine and then add some mass, x, to one side, how could you determine x, the mass added to the atwood's machine? 2. Homework Equations F = ma I would guess. 3. The Attempt at a Solution Attempt 1: F_{2net}=...
  39. J

    What force(s) make(s) change of direction in a pulley

    Hi guys .. Glad to be here in this forum of physcs fans. This is the classical problem of cart HORIZONTALLY pulled by a rope that wraps around a pulley and it's pulled VERTICALLY by say, the same mass as the cart (yeah T1 = T2 horizontal and vertical tensions .. = in MAGNITUDE BUT NOT IN...
  40. Tony Stark

    Violation of Energy conservation by use of pulley

    A person has reached H height by 100J energy whereas by the use of pulley, the man can reach the height by a fraction of that energy. In this manner, it is reaching height H by giving off less energy than required by gravitational potential energy. So isn't the law of conservation of energy...
  41. E

    Force Question -- Solidworks model of a pulley system

    Hello Everyone, I'm currently making simulations in Solidworks and am confused. I have to double the force on a pulley and change the dimensions from the original pulley, in order to withstand the new force. My hypothesis: If I multiply all the dimensions by the cubed root of 2, then my...
  42. J-dizzal

    Static equilibrium; pulley and inclined plane problem.

    Homework Statement What weight WB will cause the system to be in equilibrium? Neglect all friction, and state any other assumptions. Homework Equations ΣF=0 The Attempt at a Solution I can't figure out what I am doing wrong with these pully problems, I tried putting in resultant forces at...
  43. R

    How to Simulate Moving Loads in Ansys 15?

    Hi, I am trying to simulate a moving load in ansys 15. Could anybody guide me on how I could do it? A typical example: Calculating stress across a steel Rope ( assume solid circular c/s) between point A to B while a pulley load moves over it between the 2 points with a certain velocity. I will...
  44. O

    2 blocks connected by massless string VS. pulley system

    (Note: The title would better describe the subject if written like this: "2 blocks on a horizontal frictionless surface connected by a massless string vs. pulley system")Hello, I have a problem regarding pulling two blocks of different masses connected by a string horizontally with opposing...
  45. MironeDagains

    Why Do My Pulley System Calculations Differ From My Teacher's Measurements?

    Homework Statement There's a 200g piece of weight hanging by a string. That string is then split into two strings, each at θ from the horizontal and Φ from the horizontal. These two strings are each connected to force sensors which measure their tension in Newtons. I know how to do this...
  46. M

    Friction in a 3 block and pulley system

    Homework Statement A block of mass m1 is on top of a block of mass m2. Block 2 is connected by an ideal rope passing through a pulley to a block of unknown mass m3 as shown. The pulley is massless and frictionless. There is friction between block 1 and 2 and between the horizontal surface and...
  47. F

    Friction - 3 Blocks and a Pulley

    Homework Statement http://imgur.com/C0XYEKw Homework Equations Fnet = m*a FG = m*g fstatic = μ*N The Attempt at a Solution If both Block 1 and Block 2 have acceleration a in the x-direction and have an acceleration of 0 in the y-direction, then the force of static friction on Block 1 due to...
  48. F

    Solve Pulley Problem: Frustrated After Weeks of Trying

    Homework Statement http://imgur.com/SE50jeP Homework Equations Fnet = m*a FG = m*g The Attempt at a Solution I'm so confused about this problem and I still can't solve it after weeks. The initial distance of the workers is irrelevant. If I treat the workers and the platform as a single...
  49. R

    Mass Pulley System, Acceleration

    Homework Statement A block of 1kg is resting on an incline of 20° that has a coefficient of friction μk=0.45 with the surface. It is connected with a mass less string to a friction-less pulley of mass 0.10 kg to a hanging block of 2 kg. What is the acceleration of the system without ignoring...
  50. H

    Friction and Couples: Understanding Coefficients

    Homework Statement Usually in any question will the magnitude of the couple(friction) be given or is it possible to find the couple from the co efficient of friction between the rotating object and the axis ? Homework EquationsThe Attempt at a Solution
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