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. O

    Solve for aa = 3.38 m/s^2Pulley Quesiton Homework: Tension in Massless String

    Homework Statement The figure below shows an object on an inclined ramp of mass 0.98kg. The angle of the inclined surface is 32deg with the horizontal. The object on the ramp is connected to a second object of mass 2.13kg on a horizontal surface below an overhang that is formed by the inclined...
  2. C

    Solving Torque on a Pulley: 0.5Nm, 4kg Block, 12cm Diameter

    The problem is: The two blocks in the figure are connected by a massless rope that passes over a pulley. The pulley is 12cm in diameter and has a mass of 2kg. As the pulley turns, friction at the axle exerts a torque of magnitude 0.5Nm. If the blocks are released from rest, how long does it take...
  3. C

    Pulley Problem With Tension Direction

    In the attached picture, one sees a pulley with a mass which is holding two different weights. In chegg, the tension due to a weight is represented as a downward direction. Then, when the tension is seen in relation to the pulley, the direction switches for both weights. WHY IS THIS...
  4. A

    A friction problem containing a frictionless pulley

    Homework Statement Two masses are connected by an inelastic string over a frictionless pulley. M1 is 4 kg and the coefficient of static friction between M1 and the inclined plane Us = 0.25. What minimum and maximum amount of mass can M2 have so that M1 remains stationary on the plane? (In the...
  5. J

    Two Pulley System (Driver/Driven) power transmission.

    Homework Statement A pulley 150 mm diameter is driven directly by an electric motor at 250 revs min-1. A V-belt is used to transmit power from this pulley to a second pulley 400 mm diameter against a load of 200 Nm. The distance between the centre of the pulleys is 600 mm, the included...
  6. totallyclone

    Popeye pulling himself up using a pulley

    Popeye was lifting himself to the top of a 30m mast until he was 10 m away from the pulley. The rope was 100m long and weighed 50kg and he would pull himself off of the ground using a slow constant speed. How hard was he pulling when he was 10m below the pulley?
  7. S

    Pulley Hoist Free Body Diagram

    Hi All, I am an old dog, and rusty propeller head. I am having the most difficult time figuring out the forces on a pulley system I am working on. Can someone please review my sketch and tell me if I am even close. I would accept any suggestions and direction. Much Obliged -Steve
  8. totallyclone

    Tricky question involving masses, a pulley on incline with friction

    Homework Statement M1=5.0kg μs1=0.30 M2=? μs2=0.20 What does M2 need to be in order to move? The interesting thing with this question is if it does move, will it move up or down? Homework Equations Fun=ma Ffs=μsFn The Attempt at a Solution I thought about this and if it's...
  9. G

    Tutor (me) needs help on pulley angular accel question

    I am a high school teacher tutoring a family member in an introductory university class. I have good knowledge of typical pulley questions and semi-decent knowledge of angular acceleration (it is no longer in the high school curriculum here and I am out of practice). Can anyone give me a...
  10. R

    Exercise combining Wave and Hydrostatic: Pulley and Submerged Ball

    Homework Statement One end of a horizontal string is attached to the wall, and the other end passes over a pulley. A sphere of an unknown material hangs on the end of the string. The string is vibrating with a frequency of 392 cycles per second. A container of water is raised under the sphere...
  11. Y

    How Do You Solve a Frictionless Pulley System Problem?

    Homework Statement A light rope is attached to a block with mass 4.00 kg that rests on a frictionless, horizontal surface. The horizontal rope passes over a frictionless, massless pulley, and a block with mass m is suspended from the other end. When the blocks are released, the tension in...
  12. N

    Calculate the speed of the Cylinder in the pulley system

    Homework Statement Each of the two systems is released from rest. Calculate the speed v of each 47-lb cylinder after the 38-lb cylinder has dropped 5.2 ft. The 17-lb cylinder of case (a) is replaced by a 17-lb force in case (b). I have attached an image of the question. Homework...
  13. I

    Find the mass of m1 on an inclined pulley system

    Homework Statement Two masses ##m_1## and ##m_2## are connected by a massless cord and a pulley, on a rough ramp, tilted at angle ∅ The pulley is massless and frictionless. The coefficient of kinetic friction between the ramp and m1 is ##μ_k.## Derive an expression for ##m_1,## given that...
  14. D

    Atwood's Machine, massive pulley and upwards force acting upon it.

    Homework Statement The usual configuration of an Atwood's Machine. Two masses: m1, m2 Accelerations (unknown): a1, a2, ap (Pulley) Rope Tension: T (Unknown) BUT: Massive pulley: mp Upwards force acting on pulley (i.e the pulley is not in equilibrium): F NOTE: Consider that all the...
  15. A

    Acceleration on Inclined Plane and Pulley System

    Homework Statement I believe that I have my answer. I would appreciate it if someone could check my work. m1 = 33 kg m2 = 14 kg μ = 0.19 Angle is given by 5,12,23 triangle shown in figure. Assume pulleys are massless. What is the acceleration of mass m2 on the incline plane...
  16. D

    MHB Definition of H in pulley diagram

    Why can $H = \left(\ell - \frac{b}{\sin\theta}\right)$ where $\ell$ is the length of the rope. (everything is frictionless.) http://img690.imageshack.us/img690/579/pulley.png
  17. K

    Does the mechanical advantage of a pulley change when lifting yourself

    So basically, at my work at a science center, we have this exhibit where you lift yourself using different pulleys. I noticed that the pulleys were labeled wrong. They should have been, 1/2, 1/3, and 1/5 but were labeled, 1/3, 1/4, and 1/6. I brought this up with management and received an email...
  18. E

    How a movable pulley increases mechanical advantage?

    Firstly, I'm sorry for posting this here it seems like the best place possible, but I'm not quite so sure I didn't see a section for civil engineering. So I don't understand why a movable pulley increases the mechanical advantage. This occurs in a situation when one end of the string is fixed...
  19. J

    How Do You Solve the Moving Pulley Problem with a 100 kg Sack for Equilibrium?

    Homework Statement http://media.cheggcdn.com/media/76d/76dd5c56-43a5-44d3-b8b8-40ba63a9010a/phpYYNJyN.png Cable ABC has a length of 5 m. Determine the position x and the tension developed in ABC required for equilibrium of the 100 kg sack. Neglect the size of the pulley Homework...
  20. A

    Resultant force on a pulley system

    Homework Statement Could anyone give me an idea of how to start this problem to work out the resultant force's magnitude, direction and couple in the top (alternator) pulley? Does the 30° angle affect the equations? As all the notes I have seem to only have pulleys with the force at each...
  21. S

    Acceleration of block 1 in a pulley system

    Homework Statement http://prntscr.com/otut8 Find acceleration of block 1, knowing that the mass of block 1 is 2kg and of block 2 is 4kg. You may ignore friction and pulley mass. Homework Equations Fr = ma The Attempt at a Solution I Drew free body diagrams to block 1, 2 and the...
  22. W

    What is the relationship between angular velocity and radius in a pulley system?

    Homework Statement All data is in the attached image. The lower pulley has rotation velocity of 0.6 rad/s but I don't understand why. Both pulleys have same radius and the same rope passes through both of them so why are their velocities different? Homework Equations ω = v/r The...
  23. S

    An inclined plane, a pulley, and three masses

    Homework Statement A system comprising blocks, a light frictionless pulley, a frictionless incline, and connecting ropes is shown. The 9 kg block accelerates downward when the system is released from rest. The acceleration of the system is closest to: A.) 1.9 m/s^2 B.) 2.1 m/s^2 C.) 1.7 m/s^2...
  24. P

    For this pulley system, why is it m1g - T1-T2=m1a?

    Three objects with masses m1 = 66.0 kg, m2 = 37.4 kg, and m3 = 21.8 kg are hanging from ropes that run over pulleys. What is the acceleration of m1? (Take the upward direction to be positive.) So for the two outside blocks, I know that the forces acting on the blocks are T1=m2g+m2a, and...
  25. T

    How Do You Calculate Tension in a Pulley System with Two Masses?

    Homework Statement Sorry to be posting here but trying to look for previous similar questions I just managed to baffle me further! This is just me trying to revise and came across this.. Two masses of 10 kg and 5 kg are joined by a cable and placed over a massless frictionless pulley as...
  26. K

    A String is Connected to a Vibrating Arm and Passes Over a Light Pulley

    Here is a tricky one (for me) that uses linear mass density and two masses. I don't really know which to do so I did both! Homework Statement An object can be hung from a string (with linear mass density μ=0.00200kg/m) that passes over a light pulley. The string is connected to a...
  27. O

    Calculating Mass and Tension of Stone Suspended from Pulley

    A stone is suspended from the free end of a wire that is wrapped around the outer rim of a pulley, as shown in the figure. The pulley is a uniform disk with mass 11.3kg and radius 49.0cm and turns on frictionless bearings. You measure that the stone travels a distance 12.3m during a time...
  28. M

    Calculating the moment of inertia in a pulley system

    Homework Statement An object with a mass of m = 5.10 kg is attached to the free end of a light string wrapped around a reel of radius R = 0.250 m and mass M = 3.00 kg. The reel is a solid disk, free to rotate in a vertical plane about the horizontal axis passing through its center. The...
  29. M

    2 equal masses raised on pulley at constant velocity, what is the force ?

    Homework Statement 2 equal masses (massA, massB) are raised up a pulley, at a constant velocity. massB has a velocity twice as fast as massA. What is the force acting on these 2 masses? Homework Equations The Attempt at a Solution If it is a constant velocity, the upwards force...
  30. D

    How Do You Calculate the Acceleration of a Bucket on a Pulley System?

    Homework Statement A 2.85 kg bucket is attached to a disk-shaped pulley of radius .121 m and mass .742 kg. If the bucket is allowed to fall, what is the linear acceleration, angular acceleration, and how far does it drop in 1.5 seconds. I really only need help with the first part since...
  31. L

    How Do You Calculate the Moment of Inertia for a Pulley?

    Homework Statement A 1.3 kg block is tied to a string that is wrapped around the rim of a pulley of radius 7.2cm. The mass of the pulley is 0.31kg. The block is released from rest. If the velocity of the block is 3.0m/s after it falls 0.5m, what is the moment of inertia for the pulley?[/b]...
  32. S

    Help with a complex pulley problem

    Homework Statement The problem is based in the diagram (the jpg attached). All pulleys are ideal pulleys, and the hanging surface is massless. the problem states that the guy with mass m pulls each string with a force F, and asks to solve the value of F in terms of m and g. Since the...
  33. P

    Finding Kinetic Energy and Velocity of a pulley / block system

    Homework Statement In the problem, a hanging block, m, is attached to a pulley that is mounted on a horizontal axle with negligible friction. The pulley has a mass of M=75kg and a radius of R=6.0cm. The mass of the hanging block is m=1kg. The block is released from rest at a height above the...
  34. I

    How to find acceleration of 2 masses on a pulley on slanted plane

    ---see attachment for picture of problem--- There is no actual numbers given. We are supposed to be solving for acceleration and I tried but can't find an answer. I'll show you my work and please tell me what I did wrong Ʃfx= Ff + T - w1sinθ = m1ax = 0 Ʃfy= N - wcosθ = m1ay Ʃfx= 0 = m2ax = 0...
  35. N

    Net torque question? Block 1 and block 2 hanging on pulley?

    In Fig. 10.45, block 1 has mass m1=460g, block 2 has mass m2=500g, and the pulley, which is mounted on a horizontal axle with negligible friction ahs radius R=5.0cm. When released from rest, block 2 falls 75.0cm in 5.00 s without the cord slipping on the pulley. (e) What is its rotational...
  36. E

    Calculating Speed of Blocks in Pulley System with Spring Compression

    Homework Statement A block of 4 kg hangs from an ideal string which passes by a pulley and is attached at the other end to a block of 6kg, which is in turn lying on a rough table of friction coefficion μ=0.2. The block on the table is pushed towards a spring with elastic constant k = 60 N/m...
  37. N

    Solving a Tricky Pulley Problem: Input Forces for 200 N Load

    Homework Statement "What are the input forces needed to lift the 200 N load for the arrangement shown?" Notice how there are two movable pulleys that move in opposite directions as the weight is lifted. That is the confusing part to me. Homework Equations Ma=Fo/Fi The Attempt at...
  38. S

    How do you solve compound body problems with three masses and one pulley?

    http://www.chegg.com/homework-help/questions-and-answers/consider-situation-shown-figure-40-kg-mass-replaced-65-kg-mass-frictional-coefficient-0301-q1351583 I missed class recently, and I don't understand how to do compound body problems. Any help would be appreciated!
  39. J

    Pulley problem (Two masses acting on a third body)

    First off,I would like to apologise for not introducing myself. I have yet to find that certain part of the forum,but if the mistake was on my part,mods please direct me. Now to go to the real issue. This is something I've long "gotten over",meaning it was in the introductory lessons in...
  40. R

    Power Transmission, Gear, Pulley

    I need to lift 75 pounds when only using 4 pounds of force. Is there a gear set or pulley system that can do that? Thanks
  41. L

    What is the Acceleration and Tension in an Inclined Pulley System?

    Homework Statement please take a look at the picture m1= 4kg m2= 5kg angle is 30 degrees (surfaces are frictionless) find the acceleration and the tension what are the formulas used for solving this?
  42. E

    Two Masses on a Massed Pulley and a variation

    1a. Homework Statement Hi all, I'm having quite a bit of problem on a physics question. I've seen some examples of this problem, but when I follow the suggestions and equations out, the answer I get back is wrong... Anyways, here's the problem: Given two masses (m_1,~m_2) hanging from...
  43. S

    Blocks, Pulley, Ropes, and Tension

    Homework Statement Look at figure 4 Two blocks are attached to mass-less ropes and pulleys that have negligible mass and negligible friction. a. Find the connection between the tensions in the ropes. b. Find the connection between the accelerations of the blocks. c. Calculate...
  44. L

    Pulley system to lift container. How much force?

    1. I am stuck. Could anybody push me in the right direction? Best Regards Lasse
  45. M

    How to Solve a Spring and Pulley Problem with a 3.8-kg Sphere?

    A 3.8-kg sphere is suspended by a cord that passes over a 1.3-kg pulley of radius 3.5 cm. The cord is attached to a spring whose force constant is k = 86 N/m as in the figure below. Assume the pulley is a solid disk. (a) If the sphere is released from rest with the spring unstretched, what...
  46. K

    Horzontal Massive Pulley Problem with Friction

    Homework Statement Consider 2 masses (m1=13kg, m2=26kg) connected by a string. The pulley is a uniform disc of radius R=0.05m and mass m=1kg. μ between the horizontal surface and the larger mass is 0.2. Find Frictional force acting on larger mass. Find the linear acceleration of the...
  47. P

    HW Lab PHYS101: Net torque of pulley system and meterstick position balance

    THANKS, I ONLY NEED HELP #2 NOW, PLEASE 10/31/12 @ 9:10 pm bumpHomework Statement 1)If the fulcrum of a 0.1 kg meter stick was placed at the 40 cm mark and a 200 g mass at the 0 cm mark, would it be possible to balance the meter stick with a 200 g mass on the long side of the meter stick? What...
  48. J

    Find "x" for Pulley Problem of 5kg & 1kg Masses

    There are two bodies of mass 5kg and 1 kg on either sides of a pulley. (The string stays vertical and straight at all times). The heavier mass is doubled. The downward acceleration on the string of the hevier mass is "x". Find "x" when g=10m/s-2. Please help fast! Desperate!
  49. P

    Question about pulley with relative motion

    for part(i) the answer is g/4 + g/2 = 3g/4 ms^-2 how to calculate the acceleration of the 9N blcok relative to the small pulley to be g/4?? Did I miss something? thank you so much!o:)
  50. P

    Newtons 3rd Law (Ropes, Pulley)

    Homework Statement A 2.5 kg mass is attached to a 3.5 kg mass by a light string that passes over a friction-less pulley. The masses are released. a) What is the magnitude of the acceleration of the masses? b) What is the tension in the string? Homework Equations (I think) Ft - mg = ma The...
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