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.

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  1. M

    Motor fan pulley sizing for HVAC

    Hi Everyone! I designed a motor fan system pulley system. So, basically, the motor is of 15 kw with a driver pulley of 7" dia. And through a v-belt I attached a backward curved fan with a 10" dia pulley on the shaft. My fan shaft power is 13.24 kw. This selection was given to me by the software...
  2. Ahmed Ayman

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    Can anyone please explain to me how can I calculate the "Tension" and "acceleration" of M in this question interms of M,m1,m2 and g? I can't understand how M has an acceleration or why M is involved in the calculation of the tension my solution was that acc of M is zero and Tension = m1g x...
  3. YMMMA

    Describe what happens to a box attached to a pulley + spring

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  4. S

    Pulley System Part c: Homework Statement & Relevant Equation

    Homework Statement 2. Relevant equationThe Attempt at a Solution ...[/B] Part c) I'm confused as to how the actual pulley system works. If its balanced wouldn't it be stationary. How does it move? I thought that since its balanced the acceleration of the system is constant and therefore to...
  5. Zeke Bevan

    Newton's Third Law Problem: Two masses, a rope and a pulley

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  6. S

    Need help with a pulley and tension problem

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  7. S

    Force applied on the pulley of a system

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  8. S

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  9. J

    Finding the acceleration of two masses on a pulley system

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  10. J

    Lowering a climber with the belay rope routed through a pulley at an angle

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  11. alexi_b

    Find when the acceleration is 0

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  12. Physicsterian

    Defining equilibrium and movement in pulley arrangements

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  13. J

    Finding the force on a cord from a pulley

    (Mentor note: moved from General Eng hence not homework template) This is the given scenario. I'm trying to find the 'String R (lower part)' force. I know every other variable (the angles, string L and string R and the Rectangle is a mass m). Any help would be appreciated!
  14. P

    Energy: What will be the minimum ratio of m/M here

    Homework Statement The objects are set free from the scenario shown in the attached image. Their masses have been given and they are under the effect of gravity. The length of the string has been shown in the figure. If the two blocks cross each other, then we need to determine the minimum...
  15. sal1234

    Find Minimum Height to Lift 4kg Mass with 0.1kg Block & Pulley

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  16. J

    Distance Traveled by an object on a pulley

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  17. Beth N

    Newton’s Law of Motions: tension forces in a pulley

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  18. ForecasterJason

    Calculating actual weight lifted on a pulley weight machine

    Hi, I have a pin-loaded pulley weight home gym machine. There are 9 weight plates that are 10 lbs each, so for each exercise the maximum weight that can be done is 90 lbs. However, there is a chart in the manual that shows the weight resistance for various exercises based on how many plates are...
  19. R

    You're welcome, Rémi! Good luck with your exercise.

    Hello ! Homework Statement Two blocks M1 and M2 are connected by a string of negligible mass. If the system is released from rest, find how far block M1 slide in time ##t##. Neglect friction. Diagram: See Attached Image Clue given in the manual: If M1 = M2, then solution is ##x(t)=...
  20. J

    Using conservation of energy vs. Newton's laws in a pulley problem

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  21. E

    Basic forces question with a pulley problem

    Homework Statement A boy holds the rope so it can't move. What is the tension in point A? Homework Equations ma=F The Attempt at a Solution The answer in the book is 4N. I understand how to get it, but, I believe that the tension of S1 would be 9N (due to m1), and then the forces on m2 would...
  22. W

    2 weights on strings, 1 attached to pulley, the other end anchored

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  23. Alyssa Eiger

    Length a Block on Pulley Moves - (Basic Energy Question)

    Homework Statement Two masses are connected by a string that is passed over a massless pulley. At t=0, the 6-kg mass is moving upwards at 2m/s, while the 4-kg mass is descending at the same speed. How far will the 6-kg mass rise before it stops? Homework Equations KE= 1/2*m*v^2 PEg: m*g*h...
  24. H

    Complicated pulley system on an incline?

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  25. J

    Finding the tension of a rope given the mass of a pulley

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  26. isukatphysics69

    Can I Solve This Massive Pulley Problem Without Using Energies?

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  27. lc99

    Pulley and Pins on a Frame (beginner statics)

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  28. V

    Vector addition and the force applied to the shaft of the pulley

    Homework Statement Hello, I am currently studying mathematics and physics on my own, and I ran into a type of problem in physics that is a bit unclear to me. Say we have pulley at the top of an inclined plane with a base angle of alpha and the top angle is alpha. Homework Equations I assume...
  29. Suyash Singh

    What is the tension in part GH?

    Homework Statement Homework Equations g is the acceleration due to gravity a is the acceleration of system The Attempt at a Solution g is the acceleration due to gravity Force=3(g+a) Force=6(g-a) solving both equations, a=g/3 tension =force=4g How do i calculate tension in the particular...
  30. E

    What are the forces on the center of mass?

    Homework Statement [/B] A light rope passes over a light frictionless pulley attached to the ceiling. An object with a large mass is tied to one end and an object with a smaller mass is tied to the other end. Starting from rest the heavier object moves downward and the lighter object moves...
  31. I

    Ball suspended by a pulley: oscillation

    A ball of 100g, suspended from a pulley of a dynamometer, oscillates freely. The length of the pendulum thus obtained is 1m. What are the indications of the dynamometer when the ball is at the point A of it's trajectory? The maximum offset angle is 15 degrees. Homework Equations α - alpha...
  32. A

    How does unbalanced tension affect the motion of a rope?

    Homework Statement There is a block of known mass m on a horizontal surface. The block is connected to a pulley via a rope. The other end of the rope is pulled vertically, downwards, with a known force F. The pulley has a known moment of inertia I and radius r. Calculate the acceleration a of...
  33. Suyash Singh

    What is the formula for calculating force using a spring balance?

    Homework Statement Homework Equations only basic school level physics will be needed in this question. The Attempt at a Solution The mass m1 pulls spring from first side and m2 pulls spring from the other side therefore reading should be m1-m2. But my answer is wrong. I can't understand what...
  34. isukatphysics69

    Find the acceleration of a block on an inclined plane with a pulley

    1. Homework Statement picture Homework Equations f=ma The Attempt at a Solution Below is my attempt for part B, i am not sure what i am doing wrong here but my answer is off for acceleration
  35. E

    Question about tensions in pulley problems?

    Homework Statement The scenario I'll use specifically is in the attached file. I can understand why the pulley can have two different tensions, one for each side of the pulley, but what I don't get is why the direction of each individual tension reverses direction? For example, in the free body...
  36. isukatphysics69

    Calculating Rank Pulley Forces with Newton's Equations

    1. Homework Statement In picture Homework Equations f=ma The Attempt at a Solution i can use Newtons equations here, but i am confused about the frictional force.. so it doesn't specify whether it is a frictional or unfrictional surface.. is there something I'm missing here? does friction not...
  37. E

    Static Pulley Problem on an Incline

    The problem is: Two blocks of mass m and M are connected via pulley with a configuration as shown. The coefficient of static friction is 0.64, between blocks and surface. If the inclined angle is 23deg and M = 3.1kg, what is the maximum mass m so that no sliding occurs? The question is: I...
  38. House

    Accelerating motion with a pulley

    Let's suppose we have a body A with mass M that can move on a horizontal frictionless ground. Now we connect that with another body B, mass m, with the help of a rope. The body B can move vertically and the rope is curved with a pulley. Now we set the body B free to move. What's the relationship...
  39. S

    Disk connected to another object through a pulley on an incline

    Homework Statement A disk of radius r and mass m is placed on an incline which makes an angle of 30 degree. The disk is suspended by a string attached to its center and a mass 3m is hung at the other end. The surface of incline is rough with the coefficient of static and kinetic friction...
  40. S

    Calculating Pulley and Shaft Loads for an Existing System

    Hi, i need to do a pulley/shaft check on an existing system. Pulley is 840mm diameter and the motor has 47kw and 390 nm breakdown torque so to find the force from the belt can i assume that the force at the pulley o.d. distance is the force? So 390*0.84 will give the torque at that distance...
  41. E

    Angular Acceleration and Linear Acceleration of a Pulley

    Homework Statement There are two blocks, m1 and m2, that are hanging from a rope which passes over a pulley. The mass of the pulley is 0.15 kg. The radius of the pulley is 0.055 m. The mass of m1 is 0.165 kg. The mass of m2 is 0.18 kg. The linear acceleration is m1 is 0.3504 m/s/s downward, and...
  42. E

    Acceleration of a block on a massive pulley

    Homework Statement A block of mass MB = 0.7 kg hangs from a string wrapped around a hoop that can rotate around its center. The hoop has a mass of MH = 1.3 kg and a radius of R = 0.4 m. The block descends under the influence of gravity. What is the magnitude of the acceleration of the mass in...
  43. M

    MHB Calculate the rotational frequency in r/s and the diameter of the drive pulley

    a belt is driven by a pulley at 33m/s the pulley rotates at 750 r/min. calculate: (a) the rotational frequency in r/s (b) the diameter of the drive pulley
  44. Phantoful

    Calculate the initial acceleration of this pulley system

    Homework Statement Homework Equations W=mg F=ma The Attempt at a Solution I'm not sure how I should be answering this problem, and the diagram itself looks odd. I was thinking about how it would work in real life, since the biggest pulley is attached to the leftmost pulley, by the same...
  45. Abhimessi10

    Pulley-Block-Spring System: Understanding the Forces Acting on a Hanging Block

    Homework Statement [/B]Homework Equations [/B]The Attempt at a Solution In the second question at 5:32,why doesn't the block have a spring force.In FBD of 2nd block it should have been mg-(T+kx)=ma right?
  46. HydroMarioUSA

    Tension on Pulley HW: Block A & B Force Analysis

    Homework Statement Block B is positioned on a fixed incline. Attached to block B is a massless, ideal string that runs over a massless ideal pulley and is attached to a hanging block block A at the other end. The mass of block A is 2 kg and the mass of block B is 10 kg. The angle of the incline...
  47. Victoria_235

    How Does a Lift's Acceleration Affect the Pulley System Dynamics?

    Homework Statement Two blocks are attached by strings of negligible mass to a pulley with two radii R1=0.06 m and R2=0.08 m. The strings are wrapped around their respective radios so that the masses can move either up or down. The pulley has a moment of inertia I=0.0023 kgm2 , and is supported...
  48. I

    Pulley Acceleration and Tension Relations

    Homework Statement Determine bodies' acceleration if their masses are the following: m1 = 25kg, m2 = 1kg, m3 = 3kg and the Tension of the ropes. Friction is neglected, as well as the mass of the pulley. It is considered that the ropes are perfect. m1 = 25kg; m2=1kg; m3=3kg; ___________ a=...
  49. A

    Trouble understanding Newton's Third Law in Pulleys

    Hi everyone. I found this image online that made me question a couple of things that might be a bit humiliating to ask: I always thought that tension is simply a pulling force, meaning that the mass is suspended because the tension force pulling the mass is equal to the weight force of the...
  50. K

    Pulley problem with two masses

    Homework Statement [/B]Homework Equations F = m*aThe Attempt at a Solution [/B] Hello, i think i understand d and e so only the first three tasks are important.a) a = (m2 - m1)/(m1 + m2) *g -> (5kg - 2kg)/(2kg+5kg) *10ms^-2 = 4.29 ms^-2 T = m1 (a+g) -> 2kg (4.29ms^-2 + 10ms^-2) = 28...
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