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. H

    Friction and Couples: Understanding Coefficients

    Homework Statement Usually in any question will the magnitude of the couple(friction) be given or is it possible to find the couple from the co efficient of friction between the rotating object and the axis ? Homework EquationsThe Attempt at a Solution
  2. Mayzu

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  3. 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...
  4. S

    How to find the volume of this pulley?

    Homework Statement The problem is asking to find the volume of this pulley Formulas that is in the chapter. Area = r^2*θ/(2) Where θ is in radians Homework Equations I drew the drawing in solid works and got the volume to come out to 6.27 cubic inch. But I am not sure if this is the correct...
  5. K

    How Does the Monkey's Movement Affect the Box in a Pulley System?

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  6. L

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  7. Puddles

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  8. R

    Tension on a Rope Deflected by a Pulley: Differentials

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  9. T

    Collision involving blocks and pulley

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  10. isaac206

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  11. D

    (Vector statics) Effect of a pulley on free body diagram?

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  12. AdityaDev

    Finding acceleration of block connected to pulley with mass

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  13. ChiHawksFan

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  14. M

    Wall strength and tension on rope-pulley system

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  15. Hellmut1956

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  16. JesseJC

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  17. R

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  18. D

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  19. J

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  20. S

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  21. B

    Inclined Plane with Pulley: Finding Velocity with Tension and Acceleration

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  22. N

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  23. A

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  24. RJLiberator

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  25. wirefree

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  26. G

    Newton's second law (friction and pulley)

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  27. Dustin11H3

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  28. J

    How Do Pulley Tensions Affect Performance?

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  29. M

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

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  30. 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...
  31. 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...
  32. 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...
  33. 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.
  34. B

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    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...
  35. P

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

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  36. K

    Two masses hanging from a pulley (conservation of energy)

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  37. H

    Mass needed for static equilibrium compound pulley system

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  38. 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...
  39. Q

    Problem of fluid -- Blocks, pulley, two fluids

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  40. Y

    Massive cable and massive pulley

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  41. 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...
  42. G

    Simple Pulley Problem With Acceleration

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  43. K

    A string over a pulley, same tension?

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  44. T

    Forces; Two blocks connected by a pulley with friction

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  45. 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...
  46. F

    What is the solution to this pulley problem?

    Please help me with https://www.physicsforums.com/threads/i-need-an-answer-fast.799372/
  47. G

    What is the Correct Free Body Diagram for a Pulley System?

    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) )...
  48. 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...
  49. 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...
  50. 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...
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