What is Pulley system: Definition and 352 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.

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  1. D

    Time for Bead to Lose Contact: Solving for Friction and Tension Forces

    Homework Statement In the figure shown, friction force between the bead and the light string is ##\dfrac{mg}{4}##. Find the time in which the bead looses contact with the string after the system is released from rest. Homework Equations Weight of the bead ##(m_1)=mg## Friction acting on the...
  2. Bray__

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    Masses m1 and m2 are connected by a light string (A) over a light, friction-less pulley (B). The Axle of Pulley B is connected to another light string (C), which goes over a light, friction-less pulley (D), to a mass m3. Pulley D is attached to the ceiling by an attachment to its axle. The...
  3. M

    Acceleration and Tension in a Pulley System

    Homework Statement Consider the systems of 2kg and 5kg blocks. The 2kg block is resting upon a smooth frictionless horizontal surface and friction in pulley bearing is negligible. The 5kg block is suspended by a cord connected to the 2kg block. Determine the acceleration of system and tension...
  4. marsupial

    Coefficients of kinetic and static friction in a pulley

    Homework Statement A block of mass ## M_1 ## is on an inclined plane (the plane is inclined at 30 degrees), and is attached with a light cord over a light, frictionless pulley to another mass ## M_2 ##. ## M_1 ## is fixed at 5.00kg, and ## M_2 ## can be varied. When ## M_2 = 3.20 kg ##, ##...
  5. TiernanW

    Finding the speed of an object on a pulley system

    Homework Statement Homework Equations PE = mgh KE = 0.5mv^2 WD = F * s The Attempt at a Solution Its part i. I understand the solution when you look at the whole system. You do not need to consider the tension in the string because they cancel out, but I want to be able to do it just...
  6. D

    Angular acceleration on a pulley

    Homework Statement [/B] A mass of 6.1 kg tied to a string is wrapped around a disk as shown. If the disk has a mass of 8.2 kg and a radius of 2.3 m, how fast will the disk be rotating when the weight has fallen 7.4 m and was released from rest? Homework Equations Θ = S/R = x/R Θ = 0.5 α t^2 τ...
  7. Blockade

    Are the sum of all forces written correctly for this system?

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  8. P

    Finding the spring constant of a spring in a pulley system

    Homework Statement Ok so here is the prompt: a 3kg object is fastened to a light spring over a pulley. The pulley is frictionless and its inertia may be neglected. The object is released from rest when the spring is unstretched. If the object drops 0.1 meters before stopping, find the spring...
  9. K

    How Do You Calculate the Second Mass in an Atwood Machine Problem?

    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...
  10. W

    Work on 1 pulley system and two masses

    Homework Statement this is from an example problem in the hibbler dynamics book 13th edition in the section of work so i don't really have a question on how to do it. the question is why is the problem solved the way it is solved. the system has one pulley.one rope.and two masses at each end...
  11. jgillard1986

    Pulley System for Children's Playground

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  12. A

    Finding acceleration in multiple pulley system

    Homework Statement All the masses of the black dots are the same, the pulleys and ropes are massless. Calculate the acceleration of the right most object (the one that is just on the single hanging rope) Homework Equations Fnet= ∑F : ma=T-mg d= v1t + 1/2at^2 The Attempt at a Solution The left...
  13. Alexstrasza

    Min. and max. mass to keep pulley system stationary

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  14. W

    Statics Questions - Equilibrium in a pulley system

    Homework Statement Find the value of W to maintain equilibrium Homework EquationsThe Attempt at a Solution I have split the system into two, creating a triangle. From this I have a right angle triangle with an adjacent of 2m, opposite of 0.6m and an hypotenuse of 2.088m (calculated through...
  15. S

    Conservation of Energy in a Pulley System

    Homework Statement Two masses are connected by a light string passing over a light, frictionless pulley, as shown in the figure below. The mass m1 (which is greater than m2) is released from rest. Use the isolated system model to answer the following. In terms of m1, m2, and h, determine the...
  16. A

    Finding time in a pulley system

    Homework Statement A horizontal bar with a mass of 3.2 kg and a length L of 64 cm is rigidly mounted to a vertical spindle of negligible mass such that the two objects spin together. The spindle has a diameter of 2.0 cm, and it is attached to the bar a distance of L /4 from its centre of mass...
  17. jcruise322

    Question regarding block and pulley system with inertia

    This problem is an example from Mosca and Tipler, 9-13, 6th edition. I believe the books equation for the acceleration of the system is incorrect according to my work... Anyway, here goes 1. Homework Statement "Two blocks are connected by a string that passes over a disk pulley of radius R...
  18. K

    Power by Motor on Pulley System

    Homework Statement Homework Equations P = T*V F=ma 3. The Attempt at a Solution [/B] My approach was this: Using the pin at C as a datum, I figured that DB=CD and thus 2CD + AC = l. Thus I figured that at 3 ft/s, A was rising 3/2 feet per second. However, I also figured the it would...
  19. fissifizz

    How to find tension of a single object in a pulley system?

    Homework Statement LETTER d only [/B] Homework Equations Fnet = ma The Attempt at a Solution So I considered 2m independently and set its net force equal to its gravity minus its tension. (2m)a = Fg - Ft = (2m)g - Ft I then rearranged the equation so that Ft = (2m)g - (2m)a = 2m(g-a)...
  20. 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...
  21. B

    Dynamics - Pulley System with Rotating Rod

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  22. 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...
  23. 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...
  24. 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...
  25. K

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    This was a problem on an exam that our professor later discovered was unsolvable THE WAY HE POSED THE QUESTION. First off, it's important to note that this is from a statics class, therefore Fnet = 0 will be true for all problems in our course. So here's my thoughts on this and I would like to...
  26. A

    Equilibrium of a Collar and Pulley System with Spring - Free Body Diagram

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  27. Rinzler09

    Proof of T.a=0 rule in mechanics (Laws of motion)

    There is this T.a rule in laws of motion which can be applied to a system to solve problems regarding constraint motion. Here's an example This example is pretty simple so I've decided to show the application of the rule here. Consider the FBD of m, T is in the same direction as the...
  28. 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...
  29. 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...
  30. 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...
  31. 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...
  32. 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...
  33. 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...
  34. 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...
  35. 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...
  36. P

    How do I find rotational energy for a pulley system?

    Homework Statement So I have a horizontal pulley positioned at the edge of table with a mass of .2kg hanging down from a height of .76meters, the other end of the string is attached to a wooden block of mass .25kg that when the .2kg weight is dropped the wooden block is pulled towards the...
  37. 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...
  38. 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...
  39. 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...
  40. 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...
  41. 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
  42. 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...
  43. 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...
  44. 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...
  45. 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...
  46. F

    Dynamics Problem -- box accelerated horizontally via a mass & pulley system

    Homework Statement A 1.0 kg box on a horizontal frictionless surface is accelerated by attaching a 1.5 kg mass as shown in the diagram. What is the magnitude of acceleration of the box?(Remember, both boxes accelerate.) Homework Equations F = ma The Attempt at a Solution I drew a free body...
  47. C

    Spring Pulley System: Find Max Velocity of Block

    Homework Statement We have a system, consisting of a Disk radius R, with weight M, with a cordless string attached on its edge, at one edge of this cordless string we have a block of mass m, at the other end, we have the string attached to a spring with one end fixed to the floor, with spring...
  48. J

    Centripetal force involved with a pulley system

    Homework Statement If you have a motor pulley and a drum pulley connected by a belt then how do you explain why the belt can sometimes slip if the washing machine is rotating too fast? Homework Equations The Attempt at a Solution I know that the answer involves the tension of the belt being...
  49. T

    Unequal tension of a rope in a pulley system

    I am having a bit of difficulty with the concept of unequal tension in a rope. What are the conditions for unequal tension? I read that the tension is the same when there is no acceleration. Why is this the case? Can someone explain this concept to me? Thanks :)
  50. C

    Calculate Acceleration & Tension of a Pulley System

    Homework Statement Three equal masses are hung from a pulley(2 on one side, 1 on the other). Find the acceleration of the system and the tension between: a) the 2 sides of the pulley and b) between the 2 masses on the same side Homework EquationsThe Attempt at a Solution Got a= g/3, for a) T=...
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