What is Pulley: Definition and 1000 Discussions

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.

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

    Atwood Incline Pulley problem with two pulleys

    Homework Statement Given that a weight m1 is attached to a string going over a perfect pulley attached to another pulley suspending weight m2, and that weight m1 is on an incline with an angle of 37 degrees, find acceleration, tension, which mass hits the ground first, time needed to hit the...
  2. R

    Tension on a Rope Deflected by a Pulley: Differentials

    Hi all, first post here. I'm a junior Physics/Math double major at UMass Amherst, playing with some problems over the summer. I'll get right into it. A rope with constant tension T is deflected through the angle 2\theta_{0} by a smooth, fixed pulley. What is the force on the pulley? It is...
  3. T

    Collision involving blocks and pulley

    Homework Statement Homework EquationsThe Attempt at a Solution When the particle of mass M/2 collides with the pan ,an impulsive tension acts on the (pan+particle) . Let us call this J . Tension acting in the string between the two blocks is T . Speed of particle before collision = u =...
  4. isaac206

    Tension on Rope, greater then, less than, or equal to

    https://auddoq.dm2302.livefilestore.com/y2mGb2n5mfKxwU4nZlLmOvyElgDcG0-5GG9dGoP4AbrV1taK31XrOoPmeyf9x9RQZ8kXLi0WG2Etd0-I8bVWqOgVufahONs02hTGFS-SUwBVRyd-ajz5Eza-nrk9yWa7kF6kPFtMdPD6MGIpfwQMhywCLfOOuIO4-3tLe1_KjSf9V0/20150505_234057356_iOS.jpg?psid=1 if the image does not show here's the link...
  5. 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?
  6. AdityaDev

    Finding acceleration of block connected to pulley with mass

    Homework Statement Homework Equations a=Rα The Attempt at a Solution Free body diagrams: For larger pulley, TR=Iα ⇒ T=½MRα If this pulley rotates by some amount suchat x length of rope becomes free, and if I hold the smaller pulley at rest, then this extra length of rope comes bellow the...
  7. ChiHawksFan

    Moment of Inertia of a Disk and Pulley System

    Homework Statement Hi all, I just had a quick question regarding a problem that I have to write a lab report on. The problem involves solving for the moment of inertia of a system that involves a pulley with a hanging mass attached to a spool that turns a flywheel. The solution is supposed to...
  8. M

    Wall strength and tension on rope-pulley system

    Hello, My friend needs to transfer construction objects across a pond, came up with this idea of tying a rope between the pond and a big tree then transfer objects through a pulley, I'd like to know how to calculate the tension and will the thin concrete wall withstand the load? Here a diagram...
  9. Hellmut1956

    Model Pulley: Understanding System Physics

    Dear friends, I am a naval modelist and as i am retired due to health problems I use my project ob building a sail boat model as a red line to learn about the diverse technologies I am confronted on this path. So my goal is not that of finishing the project of my sail boat, but to learn ans...
  10. JesseJC

    Inclined plane with block and cylinder, pulley with mas

    Homework Statement Find the acceleration of the system if the mass m1 is a disk with radius R rolling down an incline which makes an angle theta with the horizontal, and the disk is connected to a pulley with mass M and radius R, which is connected to a block m2 hanging from that pulley. The...
  11. R

    Torque Calculation for Suspended Mass and Cylinder System

    Homework Statement A 16 kg mass is suspended from the end of a rope around a 22 kg cylinder with a 6.0 m diameter. What torque applied to the drive axle of the cylinder is required to accelerate the 16 kg mass 2.0 m/s^2 upwards?Homework Equations Torque = Radius cross Force The Attempt at a...
  12. D

    Rotational Inertia of a Pulley System

    Homework Statement Homework Equations Kinetic Energy = 0.5 I w^2 v = r * w torque = Inertia * angular acceleration The Attempt at a Solution That's the problem. I have no idea where to start. I assume that the end goal is to find the angular velocity, and convert to linear velocity, but I...
  13. J

    Can Increasing a Spool's Diameter Boost a Motor's RPM?

    Hi all, I have a small DC motor which turns at 20 rpm. The shaft diameter is 6mm, giving a circumference of 18.85 mm. What I want to do is get an effective rate of 30 rpm. Can I do this by simply attaching a spool or spindle to the motor output shaft with a larger diameter? If so, would it...
  14. S

    Statics: find tension/wrap angle for pulley

    Homework Statement Given: T(sub-B) plus T(sub-B) prime = 36. Both T(sub-C) values are 0. T (sub-D) =36 and T (sub-D) prime = 12. Find values of T (sub-B) and T (sub-B) prime[/B]Homework Equations OK, so we need to find the wrap angle, which should be 180 + 30 -22, which comes to 188...
  15. B

    Inclined Plane with Pulley: Finding Velocity with Tension and Acceleration

    Homework Statement A 10 kg mass is on a frictionless inclined plane 30 degrees to the horizontal. At the top of the plane is a pulley that has a rope attached to mass with tension T = 75 N. If the mass starts from rest, what is its velocity after 2 seconds? Homework Equations F = ma Vf=Vi +...
  16. N

    Spring mass pulley system frequency equation

    Homework Statement A spring is attached to the ceiling, a pulley is attached to the other end of the spring, a string is suspended over the pulley, and a mass attached to the free end of this string. The system oscillates vertically. Can someone PLEASE help me derive this equation for natural...
  17. A

    Speed of a transverse on a pulley

    Homework Statement Hi, I encountered a problem whilst doing problems involving transverse waves. If somebody could give me a pointer I would appreciate it. The question is: "One end of a horizontal rope is attached to a prong of an electrically driven tuning fork that vibrates the rope...
  18. RJLiberator

    Energy Methods + Pulley + Friction, finding final velocity

    Homework Statement The pulley in the figure has radius R=0.160m and a moment of Inertia I_p = 0.560 kg*m^2. The rope does not slip on the pulley rim. As m_4 (4kg block) drops due to gravity, m_2 (2kg block) is dragged up a ramp inclined at theta = 65 degrees. The coefficient of kinetic friction...
  19. wirefree

    Two cylinders: free to fall and rotate

    Problem: Find the acceleration of the blue cylindrical disk. Both, red and blue, cylinders have same mass and radius, and string is massless. Attempt: Identified three equations: one for linear acceleration of blue cylinder, and two of angular accelerations (one each for blue and red...
  20. G

    Newton's second law (friction and pulley)

    Homework Statement Homework Equations F=ma, Fr = μN The Attempt at a Solution 1kg(1m/s^2) = 1N Fnet = (x) - 1.18 1N = x - 1.18 x = 2.18N 2.18N/9.81m/s^2 = 0.223kg I know this is not right because I was told that in my calculations Fnet and Fr go in the same direction. Also I didn't use...
  21. Dustin11H3

    Angle/Coordinate Calculation for two "Pulley" System

    Hello everyone. This is my first post on here. I figured that I would give it a shot. Just as a quick background: I'm studying electrical engineering and I'm working an internship for a machine manufacturing company now. One of the projects I have been assigned is to come up with a system to...
  22. J

    How Do Pulley Tensions Affect Performance?

    Hi I am new to this site, I'm currently studying my Engineering Foundation degree and I am massively struggling on the theory side to pulley tensions. Please could anybody point me to some sites or some information which would help me understand and answer this question in detail. I have not...
  23. M

    Find the weight of a sphere connected to a pulley and to wall

    Homework Statement The system of 2 spheres is in equilibrium. Figure: . If the weight of the second sphere P2=20N, ABC=60 degrees and BAC=30 degrees, find the weight of the first P1 and the force that is applied on the drum of the pulley. Homework Equations P1=m*a The Attempt at a Solution...
  24. L

    Acceleration of two masses on pulley.

    Homework Statement Two masses are connected by massless and frictionless pulleys and string. The coefficients of friction are µs = 0.35 and µk = 0.25 between mass m1 and the table. The masses are m1 = 8.0 kg and m2 = 8.0 kg. Find the acceleration of each mass and the tension in the string...
  25. A

    How Does Hanging a Weight Affect the Sag and Tension in a Pulley System?

    Suppose we have a weight D (1 Kg) hanging from a pulley on a rope connected to a wall A suppose also the distance AB from the wall is 1 m. If I hung a weight C =1 kg as a counterweight and the pulley were not connected to the wall, the length of the rope BD (1) would equal the length of the...
  26. D

    Mechanical energy of frictionless pulley

    Homework Statement In the system shown, the block M (mass of 15.65 kg) is initially moving to the left with a speed of 3.4 m/s The mass of m is 8.26 kg and the coefficients of friction are μs=0.411 and μk=0.304. The string is massless and the pulley is massless and frictionless. How fast will M...
  27. H

    Finding Power Ratio of Two Pulley Systems

    Homework Statement Part C: http://imgur.com/mFlXGZs Homework Equations Power = τω The Attempt at a Solution P1/P2 = τ1ω1/τ2ω2 = (T1/T2) * (ω1/ω2) T1/T2 is found in part B: r1/r2 (ω1/ω2) = vr1/vr2 (velocities are the same) = (r1/r2) (r1/r2)*(r1/r2) = (r1)^2/(r2)^2 The answer is 1.
  28. B

    System in static equilibrium given a nudge. What happens?

    We're given a problem: A 2.0 kg mass hangs from a rope attached to an unknown mass m on a frictionless ramp inclined at 20 degrees above the horizontal. This is drawn as a diagram which shows the incline at 20 degrees where the hanging mass is 2.0 kg and the attatched mass on the frictionless...
  29. P

    Rope Slipping in Pulley System: Does ##\ddot{l} = 0##?

    In this derivation (see attached image), does the author assume that the rope doesn't slip? Because if it does, then there is no guarantee that ##\ddot{l} = 0##, right? Also, does this equation apply to all pulley systems where one pulley is fixed and the other is allowed to move? For example...
  30. K

    Two masses hanging from a pulley (conservation of energy)

    Homework Statement Two masses are connected by a string that hangs over a frictionless pulley with mass 8kg, radius .25m, and moment of inertia .5mr^2. One mass lays on the ground and has mass 15kg. The other mass is 22.5 kg and is 2.75 m above the ground. Use conservation of energy to...
  31. H

    Mass needed for static equilibrium compound pulley system

    Homework Statement For what m1 will the illustrated pulley system be in static equilibrium if m2 = 60 kg? Homework EquationsThe Attempt at a Solution im supposed to use the change in lengths but don't know how to do it
  32. T

    Engineering, Statics -- A pulley is free to move on the cable

    Homework Statement 1. Pulley B is free to move on the cable ABC which is fastened at A and being pulled by force F through the pulley C. Neglecting friction: a. Determine location of point B as a function of d. b. Express the force F required to maintain equilibrium in terms of P...
  33. Q

    Problem of fluid -- Blocks, pulley, two fluids

    Homework Statement dynamic viscosity 1 = 1125 2 kgf-s / m2 , dynamic viscosity 2 = 62.5 2 kgf-s / m2 , Areas: A1 = 20 cm2 , A2 = 50 cm2 W1 = 15 Kgf, W2 = 40 Kgf. The block (2) is displaced downwards with a constant speed of 80 mm / sec, whereas linear velocity distribution determined: 1) The...
  34. Y

    Massive cable and massive pulley

    Homework Statement A cable of length L and mass density λ is rolled on a pulley of mass m and radius r, with its tip hanging. The cable starts to unravel and fall due to gravity; the system starts from rest. Assume the cable has negligible thickness and rolls without slipping on the pulley...
  35. J

    Aceleration & tension in a system involving pulley

    1. Homework Statement I am stuck on this problem involving tension, acceleration of a system, friction and a pulley. I have an idea of how to find the acceleration of the system neglecting the mass of the pulley, but it is not the solution. How does adding a frictionless pulley in the system...
  36. G

    Simple Pulley Problem With Acceleration

    Homework Statement Block A in the figure has a mass of 5.00kg , and block B has mass 12.0kg . The coefficient of kinetic friction between block B and the horizontal surface is 0.25. What is the mass of block C if block B is moving to the right and speeding up with an acceleration 3.00m/s2 ...
  37. K

    A string over a pulley, same tension?

    Hi, I am new here! 1. There is no actually data given, I am just supposed to explain why a string that crosses a pulley have the same tension both sides. The pulleys moment of inertia is zero and friction is negligible. There is a little hint in this problem that says; study equation 9-15...
  38. T

    Forces; Two blocks connected by a pulley with friction

    Homework Statement A massless rope is attached to Block A, which as mass m_A and rests on a horizontal surface with coefficient of kinetic friction u_k. The rope passes over a frictionless, massless pulley and Block B is attached to the other end. When the blocks are released, Block A moves to...
  39. G

    Pulley System Question: Find Relationship Between Force and Tension

    Homework Statement Hi Guys, I am looking at a simple movable pulley system like the one two in from the left. I am trying to work out the relationship between the force applied to the free end (called F2 in the picture) and the tension in the cable Homework EquationsThe Attempt at a Solution...
  40. F

    What is the solution to this pulley problem?

    Please help me with https://www.physicsforums.com/threads/i-need-an-answer-fast.799372/
  41. 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) )...
  42. Y

    Inclined plane and pulley: how to know the acceleration's direction

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

    Pulley suspending two different masses lifted upwards

    The force F pulls upwards two masses, m1 and m2(m2>m1), which are connected to each othet via a massless pulley. The masses are perched on the ground before movement starts. A. What is the acceleration of each one of the respective masses in each of the following situations: 1)F<2*m1*g...
  44. M

    Designing a Pulley System to Increase Weightlifting Force

    Hi, I am building a simple pulley for a weightlifting machine. In most cases pulleys are designed to lift heavier loads easier, I want to actually make it harder to lift the load… So I don't have to put so much weight on the end. Can I amend my simple pulley design in a (simple) way to...
  45. P

    Analyzing Forces in a Platform and Pulley System

    A girl stands on a platform and pulley system. The masses of the platform, girl and pulley are M, m and u respectively. The rope is mass-less. Let the girl pull up on the rope so that she accelerates a upwards. What is the tension of the rope? What is the normal force between the person and the...
  46. J

    Solving for different masses in pulley system with KE

    Homework Statement So I am stuck on this homework problem. I understand the general direction I have to take, but my algebra and physics aren't good. Here's the problem: A simple Atwood's machine uses two masses, m1 and m2. Starting from rest, the speed of the two masses is 10.0 m/s at the end...
  47. Wayland Bugg

    Rope tangent angle over pully given position of offset load

    I am trying to symbolically resolve the angle of rope that suspends a load (rectangle) between two pulleys given the length of rope that is let out over the pulleys. See attached image. the load is not intended to move horizontally, only vertically. so you can imagine each pulley must have an...
  48. terryds

    Pulley Problem (with force upward)

    Homework Statement http://www.sumoware.com/images/temp/xzstefmnkmsctpxh.png A man pulls up a pulley shaft with force F (see the picture above) Assume that the pulley and cord have no mass, and the mass of object 2 is bigger than the mass of object 1. a) Determine the maximum normal force to...
  49. B

    Acceleration of massless pulley and blocks

    Homework Statement Consider a situation I'm curious why is that the massless pulley's acceleration is just the avarage of acceleration of m1 and that of m2? ab=(a1+a2)/2 Homework Equations Forces acting on pulley are Tc-2Ta=0 (because pulley is massless, force can't give it acceleration)...
  50. A

    Tension with a pulley question

    Homework Statement Homework Equations us*Fn = Fs FNET = ma Fk = us*Fn 3. The Attempt at a Solution A 0.42*9.8*4.4 = Fs Fs = 18.1104N B F = ma m = 18.1104N/9.8m/s/s m = 1.848kg 1.848kg-0.120kg = 1.728kg for the washers to make up for 1.728kg/(0.02kg/washer) = ~86 washers C I'm not sure...
Back
Top