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. Haniah

    Calculating Toolbox Mass in Horizontal Pulley System

    Homework Statement A group of construction workers are building a house and want to lower down an excess bundle of 1400 kg bricks to ground. They tie one end of a rope to the bundle of bricks, loop it through a pulley, and tie the other end of the rope to a toolbox. If the coefficient of...
  2. C

    Masses Over a Uniform Cylindrical Pulley

    ηϖ1. Homework Statement Homework Equations I=½MR2 PE=mgh The Attempt at a Solution The first thing that jumped out at me was "uniform cylinder" so I went ahead and calculated the moment of inertia for the cylinder and got I=½(4.4)(.4)2 = .352 and held onto that. Then, I calculated the...
  3. C

    Masses over a Pulley (w/ angular kinematics)

    Homework Statement http://imgur.com/koz4PpI Homework EquationsThe Attempt at a Solution I was able to calculate the net torque on the pulley as 55.88 and the Inertia as .352. Those could be wrong, but that's as far as I could get. I really have no idea. Any kind of help/explanation would be...
  4. deusy

    Acceleration of the end of a hinged rod in a pulley system

    Homework Statement As shown in image. 2. Homework Equations Moment of inertia of pulley = 1/2*M*R^2 Moment of inertia of rod (about end) = 1/3*M*L^2 Acceleration of end of rod in theta direction = L*α Acceleration of end of rod in radial direction = L*ω^2 The Attempt at a Solution...
  5. Adriano25

    Pulley Problem: Find the acceleration of M2 & M3

    1. Homework Statement Pulley is mass less accelerating downward at 2.0 m/s2. M1 = 4.0 kg M2 = 2.0 kg M3 = 3.0 kg Find the acceleration of M2 & M3. Homework Equations I made up the slope positive pointing up. Since M2 and M3 have the same acceleration, a2=a3 ⇒ a Since it's accelerating...
  6. Eclair_de_XII

    How do I calculate the acceleration of the C.O.M. of a pulley system?

    Homework Statement "Figure 9-44 shows an arrangement with an air track, in which a cart is connected by a cord to a hanging block. The cart has mass ##m_1=\frac{3}{5}kg##, and its center is initially at xy coordinates ##(-\frac{1}{2}m,0)##; the block has mass ##m_2=\frac{2}{5}kg##, and its...
  7. F

    Find work given a pulley and two weights

    Homework Statement Problem 6.65 Two blocks are connected by a very light string passing over a massless and frictionless pulley (Figure (Figure 1) ). The 20.0-N block moves 75.0 cm to the right and the 12.0-N block moves 75.0 cm downward. Question: Find the total work done on 20.0-N block if...
  8. B

    Pulley system on rough surface.

    Homework Statement [/B] Question :- Find the acceleration of block of mass ##M##. The coefficient of friction between blocks is ##\mu_1## and between block and ground is ##\mu_2##. free body diagram at the end. Variables :- ##f_1## - friction between blocks. ##f_2## - friction between block...
  9. V

    Block on movable wedge pulley system

    Homework Statement What is the relationship between " acceleration of block with respect to wedge" and "acceleration of wedge " ? Homework EquationsThe Attempt at a Solution If the wedge moves by x units , then the string gets loosened/shortened at three places . The top two are x units...
  10. S

    Help With Pulleys: Answers to Acceleration Questions

    A block of mass m1 is attached to a block of mass m2 by a massless rope (see diagram); the pulleys and surfaces are frictionless. When the blocks are let go, they move. Answer the following three questions using the choices given below. i) Select the correct expression for the relationship...
  11. K

    Pulley Question, mechanics question

    Homework Statement Two particles A and B of mass 4kg and 3kg respectively are connected by a light inextensible string which passes over a small smooth pulley. The particles are released from rest with taut. When A has traveled a distance of 2m it strikes the ground and immediately comes to...
  12. S

    Calculating Tension & Reactions in an Unbalanced Pulley System

    Homework Statement An unbalanced pulley 8in. radio. and 32.3 pounds weighing. It has a radius of gyration of 6in with respect to its axis. When a pair M = 100pie.lb applies, lifts a weight W = 96.6 pounds. In the position shown in the figure, the pulley has an angular velocity of 3 rad / sec...
  13. P

    Statics Double-Mass Pulley Incline Problem

    Homework Statement Homework EquationsThe Attempt at a Solution I'm having trouble coming up with the equations for the system. At first, I thought that m2 = m1sin(theta), but that's not correct. How can I set this problem up?
  14. V

    Forces pulley and bricks Problem

    Homework Statement I have a man who is 100kg and a barrel of bricks weighing at 220kg. The man is using a pulley to lower the bricks onto the ground however since they are much higher in weight he rapidly travels up. Then the bricks fall onto the ground and the barrel weighs 60kg since it's...
  15. C

    Why Does a2 Equal m1g/m2 in an Accelerating Pulley System?

    a1 = a2 a1 = F/(M+m1+m2) | Force/(Mass of entire system) = acceleration of entire system *a2 = (m1g)/(m2+m1) | Force = m1g; acceleration of m2 and m1 = m1g/(m1+m2) My answer: F = (m1g)(M+m1+m2)/(m2+m1) The book's answer: F = (m1g)(M+m1+m2)/(m2) *This step is what leads me to a slight variation...
  16. Turkus2

    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...
  17. nysnacc

    Solving Pulley Type Problem: Mass, Forces & Momentum

    Homework Statement Homework Equations Sum of Force g = 32.174 ft/ s^2 The Attempt at a Solution I consider the right hand side weight, T = -mg = - 10*32.174 = 321.74 lb Why is the answer 3.33, which seems to be even smaller than the mass?? Should I consider the momentum, or something with...
  18. W

    Identifying the Potential Energy of a Spring Pulley System

    Homework Statement Homework Equations U = 1/2 kx2 The Attempt at a Solution So, I took dynamics off campus and needless to say, we didn't really do very much deriving so that aspect of physics really bogs me down and I'm trying to learn it now in another class. So if anyone wants to also...
  19. donaldparida

    Weight of pulley with mass attached to it.

    Suppose there is a pulley(of negligible mass) and a string(of negligible mass) passes through the groove and two equal masses are attached to each end of the string. Now, if the whole arrangement is attached on a spring balance what will be the reading of the spring balance. Will it be zero?
  20. Mr Davis 97

    Accelerations in a Three Mass Pulley System: How Are They Related?

    Homework Statement The system of masses M1, M2, and M3 in the sketch uses massless pulleys and ropes. The horizontal table is frictionless How are the accelerations related? Homework EquationsThe Attempt at a Solution I feel like the solution will come from the constraint equation involving...
  21. Mr Davis 97

    Two masses and two pulleys problem

    Homework Statement Masses M1 and M2 are connected to a system of strings and pulleys as shown. The strings are massless and inextensible, and the pulleys are massless and frictionless. Find the acceleration of M1. Homework Equations Newton's 2nd Law of motion The Attempt at a Solution So...
  22. K

    2 masses, a massive pulley and an inclined surface

    Homework Statement [/B]A mass m lies on an inclined surface with equal coefficients of friction μ=μs=μk. the pulley has also mass m and the weight is 2m. what is the velocity after it has descended distance h and during how much time. Homework Equations Moment of inertia of a massive disk...
  23. Alexanddros81

    Related Rates of Accelerations in Pulley Problem

    Homework Statement Hi! I am new to this forum and i have problem understanding sample problem 13.5 from Vector Mechanics for Engineers 10th edition Statics and dynamics. (Beer) In particular I don't understant in part b how he comes to the assumption aC=-1/2aD If anyone can help thanks...
  24. C

    Two pulley and three mass system

    Homework Statement A light pulley can rotate freely about its axis of symmetry which is fixed in a horizontal position. A light inextensible string passes over the pulley. At one end the string carries a mass 4m, while the other end supports a second light pulley. A second string passes over...
  25. D

    Force does work -- Two masses and a pulley system....

    Homework Statement Two blocks ##A## and ##B## having masses ##m_1= 1 kg, m_2 = 4 kg## are arranged as shown in the figure, The pulleys ##P## and ##Q## are light and frictionless. All the blocks are resting on a horizontal floor and the pulleys are held such that strings remain just taut. At...
  26. D

    Condition to not let the block descend

    Homework Statement In the system shown in Fig. ##2E.5 (a)##. block ##m_2## is being prevented from descending by pulling ##m_1## to the right with force ##F##. Assuming all the surfaces to be frictionless, Find ##F## Homework Equations F.B.D of ##m_1## From the F.B.D of ##m_1## we get the...
  27. J

    Moment of Inertia of Massless Pulley w/String & Mass m Attached

    What is the moment of inertia of massless (ideal) pulley that has a string attached to its center and a mass m attached to that string? If this pulley were hanging from a massless rope that was attached on one side to the cieling and the other side had a tension of mg, what would be the...
  28. Eclair_de_XII

    Finding static friction of a block on a table on a pulley?

    Homework Statement "When the three blocks in Fig. 6-29 are released from rest, they accelerate with a magnitude of ##0.500 \frac{m}{s^2}##. Block 1 has mass M, Block 2 has mass 2M, and Block 3 has mass 3M. What is the coefficient of static friction between Block 2 and the table?" Homework...
  29. F

    Combined Stress of Cable Around Pulley

    I have an application where I'm trying to lift an object by using a pulley and pulling on the cable. We were forced to use a pretty small pulley and thin cable, so my question is how to analyze the total stress of the cable? I should be looking for axial stress, bending stress (cable around...
  30. MartinLoland

    Transfer of forces from a pulley to a beam

    Homework Statement I am trying to understand how forces transfer from a wheel / pulley onto a beam, and then calculating the resulting moment. The image describe the problem. The rope is in tension with force "S", the wheel/pulley can rotate freely without any friction. Homework Equations...
  31. 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...
  32. C

    Rolling & Pulley Homework: Find Max Mass for Cylinder to Roll

    Homework Statement A solid cylinder is attached by a rope on its center.It has mass of 5kg and is lying on a table.The other end of the rope is a block of mass m2 which is not on the table .if the coeficient of friction between cylinder and table is 0.2.Find the maximum mass 2 so that the...
  33. J

    Feynman's (err, Gottlieb's) infinite pulley problem

    Homework Statement OK, I've worked up my nerve to ask a stupid question about this problem. I've read the various discussions of it, but I'm clearly missing something.2. Homework Equations [/B] The right-hand mass is 1/(1-t). The sum of the left-hand masses (an infinite series) is also...
  34. Giannakoulis

    Helping out with pulley diameter calculation

    Hey guys.. Sorry for my english, i'am only 16 and it's not my parent language. I need help about a problem on mechanical engineering, and i really appreciated if you can help me out. I assume that I've got a moter currents which gives me out 220-230 Volt trend, and has 1800 bends per minute. Now...
  35. 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 ##, ##...
  36. Clara Chung

    Rotation dynamics pulley concept confusion

    Homework Statement A light string is passed over a pulley and two masses m1 and m2 are suspended from the two free ends. The pulley is a uniform circular disc of mass M. Find the linear acceleration of the two masses. Friction may be neglected. Homework Equations I through center of the disc =...
  37. G

    Pulley systems and friction (simple or compound)

    This is a two part question: 1. With a simple pulley system using one pulley - say 10000 kg on each side - the ability to pull either one up or down to change the position is theoretically just the friction on the system and any extra length of rope on one side? 2. Would it be more work lost...
  38. S

    How Do You Calculate the Dynamics of a Mass Suspended from a Flywheel?

    Homework Statement A mass of 0.5kg is suspended from a flywheel, if the mass is released from rest and falls a distance of 0.5m in 1.5s calculate: A, the Linear acceleration of the mass B, the angular acceleration of the wheel C, the tension in the rope D, the friction torque. Known...
  39. B

    Calculate Tension in the String

    Homework Statement Two blocks are connected by a massless string that passes over a frictionless pulley. The coefficient of static friction between m1 and the table is 0.45. The coefficient of kinetic friction is 0.35. Mass m1 is 45kg and mass m2 is 12kg. Determine tension in the string. ***I...
  40. S

    Static Equilibrium Pulley Problem

    Homework Statement The attachment above contains the diagram given in the problem M1 = 25kg M2 = 35kg Friction coefficient between M1 and stucture = 0.15 Friction coefficient between M1 and M2 = 0.25 Friction on pulleys and mass on pulleys is negligible. Find the minimum mass M3 for sliding...
  41. D

    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...
  42. A

    Two blocks connected with spring and pulley

    Homework Statement A block of mass m1= 20.0kg connected to a block of mass m2 =30.0 kg by a massless string that passes over a light, frictionless pulley. The 30.0-kg block is connected to a spring that has negligible mass and a force constant of k =250 N/m as shown in Figure P8.64. The spring...
  43. 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...
  44. L

    Friction problem involving a block and pulley on a ramp....

    Homework Statement In the system, find minimum weight of the block 'B' to start the motion of the block 'A' up the plane.weight of block 'A' 10 KN. The angle of friction for the block and the incline,between the pulley and the string may be assumed as 15° (assume pulley is locked) Homework...
  45. P

    Second Newton's law in rotation with pulley.

    Homework Statement The rope doesn't slide on the pulley, it's mass is negligible and it doesn't stretch .The pulley's moment of inertia is 0.00300 kg * m^2 with a radius of 10 cm. As the first mass goes down the rope's friction generates a moment of force of 0.150 N*m opposed to the angular...
  46. 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...
  47. Sahil Kukreja

    Rotational Dynamics Pulley Problem Help needed

    1.) Homework Statement A Pulley System is shown below Find the accelerations of m1, m2 and m3 (such that there is no slipping between the disk and the rope.) Assume the threads to be massless. Homework Equations The Relevant equations i think are Newtons 2nd...
  48. Daisy Muller

    What Happens to Angular Acceleration and Moment of Inertia in a Pulley System?

    1. Homework Statement In each question: you place mass m on the mass holder, and released the system from rest. The system includes the long rod with two point masses on it (see the picture next to the list of equipment). Since this is a rotational and translational motion, I set up two...
  49. S

    Question about static friction adjusting itself

    In a situation like this, there are two equilibrium's, For just about to accelerate downwards: mgsinθ - Ffriction - T = 0 For just about to accelerate upwards: T - Ffriction - mgsinθ = 0 Is there a situation where there is no static friction i.e. when mgsinθ = T?
  50. I

    Pulley Force Vector: Check Friction on 10kg Weight

    I'd like to ask the question as above, I think it successfully acted as a lever and redirected the force vector perpendicular to the arm of the machine, but it does've > friction, reducing the force acting on the 10kg Weight, could anyone that knows pls help check for me?*Edit, ... I think it...
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