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

    What is the acceleration of each mass in a pulley system with two masses?

    2 masses are tied in the followin configuaration, the 1st with a mass of m1 the 2nd mass of m2, pulleys and ropes have no mass or friction. what is the acceleration of each mass, using only parameters g, m1, and m2...
  2. A

    Pulley System: Solving for Acceleration (a3)

    Homework Statement Hey guys. Look at this pulley system, I wrote down all the equations. The pulley on the left is massless, the one on the right has the mass of m3 and radius R. I also wrote the the torque equation of the pulley and the thing I don't understand is the what is the...
  3. A

    Simple Pulley System: Accelerations Equation Explained

    Homework Statement Hey guys. I have the following pulley system (in the pic). I wrote down all the equations. The thing I don't get is the accelerations equation (a1 = 2*a2). I understand that I can get to this equation somehow by the length of the rope, but how? Thanks. Homework...
  4. H

    Tension and Acceleration in Pulley System

    I recently did a problem where two masses were connected to the same massless string in an Atwood's machine, yet they had different accelerations. This wasn't really intuitive to me. If one mass had a greater magnitude of acceleration than the other mass, then it would imply that the bit of...
  5. A

    Analyzing Pulley System: Acceleration and Masses

    Homework Statement Hey guys. look at this pulley system. I drew all the forces, and also, the pulleys have no mass and so as the rope. What do you say about the equations I wrote, are they right? And BTW the first part of the question is to figure which mass has acceleration bigger then g and...
  6. F

    Tension Equal in Pulley System w/ 2 Strings

    This is a general question... Given a pulley system that consists of one pulley and 2 strings--each with a mass hanging from it. One mass is 3kg, the other is 4kg. In class we concluded that the tension on each string was equal--why?
  7. T

    Work done using a pulley system

    Homework Statement There is a pulley system, identical to system (ii) in the following image: http://www.phys.unsw.edu.au/~jw/graphics/blocks1.GIF A 1.24 kg canister hangs from one pulley, you are lifting with constant speed, what is the work you do while lifting the canister 1.60 cm and...
  8. C

    Energy and WET (Incline pulley system)

    A m1 = 45.0 kg block and a m2 = 105.0 kg block are connected by a string as in Figure P7.44. The pulley is frictionless and of negligible mass. The coefficient of kinetic friction between the 45.0 kg block and incline is 0.250. Determine the change in the kinetic energy of the 45.0 kg block as...
  9. K

    Solving Two-Block Pulley System w/Expln

    Homework Statement As part a of the drawing shows, two blocks are connected by a rope that passes over a set of pulleys. One block has a weight of m1 = 312 N, and the other has a weight of m2 = 758 N. The rope and the pulleys are massless and there is no friction. (a) What is the...
  10. DocZaius

    Pulley system with a weight's acceleration of g/5

    Homework Statement In the system shown in the figure (see attachment), the pulleys on the left and right are fixed, but the pulley in the center can move to the left or right. The two masses are identical. Show that the mass on the left will have an upward acceleration equal to g/5. Assume...
  11. C

    Simple pulley system + kinetic friction, find tension

    A 9.00 kg hanging weight is connected by a string over a light pulley to a 5.00 kg block that is sliding on a flat table (Fig. P5.8). If the coefficient of kinetic friction is 0.560, find the tension in the string. fk = µkN, F = ma, N2 = m2g, 5.00 kg mass = m2, 9.00 kg mass = m1 N =...
  12. N

    Lagrangian Mechanics - Pulley System

    Homework Statement Here's a little diagram I whipped up in paint: http://img83.imageshack.us/img83/7625/diagramcj4.th.jpg Sorry about my sucky art skills. The wiggly line is a spring with spring constant mk and natural length d. The actual length of the spring is y. The two masses to...
  13. D

    Unknown mass on a pulley system - Help

    Homework Statement The 100 kg block shown in the diagram takes 6.0s to reach the floor 1.0m below after being released from rest. What is the mass of the block on the left?Homework Equations Newton's Third Law F=ma F (a on b) = -F (b on a)The Attempt at a Solution I don't even know where to...
  14. G

    Acceleration in a Pulley System

    For the system in the figure mass m1 is 10 kg and mass m2 is 5 kg. What is acceleration of m1 if the horizontal surface is frictionless? Hint: How does a1 compare to a2? http://geocities.com/grouchy187/untitled.bmp My attemp: T = m1a T - m2g = m2a m1a = m2g + m2a a= m2g / m1-m2
  15. R

    Two Pulley System: Equilibrium & Theta Calculation

    http://users.on.net/~rohanlal/Q40.jpg Does the tension in the rope from B to A and from A to C remain the same? To determine the value of theta when the system is in equilibrium do I need to calculate the sum of all acting x and y components? If so would B and C be negative and A be positive?
  16. R

    Determining T and Theta in a 10kN Pulley System

    http://users.on.net/~rohanlal/Q5.jpg The maximum force of the block, T, must be determined. The 2nd rope that the pulley is attached to has the same maximum tension force as the rope of the pulley which is 10kN. Theta also needs to be determined.
  17. C

    Solving Pulley System Dynamics: Acceleration & Tension

    Two masses are attached to a massless, frictionless pulley as shown. (image is attached) A) Find the acceleration of the two masses and the tension of the rope connecting them. B) Now the top surface is replaced with one which has a coefficient of kinetic friction of 0.2. FInd the...
  18. S

    Newton's Third Law and Pulley system

    The lower block in the figure is pulled on by a rope with a tension force of 20 N. The coefficient of kinetic friction between the lower block and the surface is 0.30. The coefficient of kinetic friction between the lower block and the upper block is also 0.30. What is the acceleration of the...
  19. L

    Calculating Tensions and Acceleration in Frictionless Pulley System

    The weights of the objects are 200 N and 300 N. The pulleys are essentially frictionless and massless. P1 has a stationary axle but P2 is free to move up and down. Find the tensions FT1 and FT2 and the acceleration of each body. Diagram I made in paint attached. Now my problem is not that...
  20. R

    Closed Loop Pulley System, which scenario is better?

    Hi Friends, We are stuck between two scenarios here on a closed loop shade system we are putting together. First, the way this system works is there is a roller containing a shade panel wrapped around it (just like a window shade) and the shade panel connects to a hem bar. Then a steel cord...
  21. P

    The "Lifting Your Fridge with a Pulley System

    Homework Statement You wish to put your fridge on the second floor of your house (again). You decide to rig up a pulley system so as to not overexert yourself. Your maximum force is 250N and the fridge weighs 950N. a) diagram a pulley system using the fewest number of pulleys, which can...
  22. L

    Acceleration in a Pulley System

    Hey, I'm doing a review packet for my AP Physics class, and I was just looking for some confirmation that I'm on the right track. Here's the image of the problem: http://img297.imageshack.us/img297/2681/imgrx6.jpg Ignore the scribbles. I'm using the formula a = ((mB)(g)- (µ)(mA)(g)(cos...
  23. A

    Pulley system for telescoping crane

    Hey guys, I'm trying to figure out how the pulley system / gearing works on something like this - http://www.chapman-leonard.com/products/telescoping%20crane%20arms/15'%20Telescoping%20Hydrascope.htm Basically some kind of pulley system make the front 2 telescoping sleeve move in and out...
  24. K

    Pulley System: Acceleration & Angular Acceleration

    Homework Statement Given a frictionless pulley system with the pulley having a mass 1/3M and radius R, and two weights of mass M and 4M attached to a light, frictionless rope on either side of the pulley: 1) Find the acceleration of the blocks 2) Find the angular acceleration of the...
  25. B

    Solving a Pulley System: Friction, Tension & Acceleration

    Homework Statement http://img214.imageshack.us/img214/6531/pulleysystemph6.th.jpg Homework Equations sum of forces The Attempt at a Solution So I tried summing the forces in the x-direction where m*a (block a) = -Ff + T = m(block a)*g*u + m*a(block b) + m*g(block b)...
  26. G

    Rotational Energy and Pulley System

    Homework Statement Problem reads: The pulley in the figure has radius 0.160 m and a moment of inertia 0.480 kgm^2. The rope does not slip on the pulley rim. Use energy methods to calculate the speed of the 4.00-kg block just before it strikes the floor. Homework Equations...
  27. S

    Kinetic Energy of Pulley System with Unequal Weights

    Homework Statement Force of gravity = 10 http://img80.imageshack.us/img80/1156/kineticec6.png http://img80.imageshack.us/img80/1156/kineticec6.png Pulley System Two unequal weights, A = 6KG and B = 4KG What is the kinetic energy of the movement after 4 seconds? I think my calculations are so...
  28. W

    Calculating Weight Pull for a Pulley System

    i have a 230lb weight i need to lift 12feet in the air. i have a 2 1/8 inch dia. pulley directly above it, and then 17 feet horizonally i have a 3 inch dia. sheave block. Than i drop straight down 25 feet to another 3 inch dia. sheave block which is turned at a 30 degree angle to the sheave...
  29. A

    What are the equations for equilibrium in a pulley system?

    The problem involves a picture so i posted it so it can be seen and easier or you guys to help me i know that the total sum of the tensions in this need to equal 37.4N + 61.4N but i get confused when angles get brought into play link to problem...
  30. T

    Solving Acceleration of Blocks in Pulley System

    Homework Statement Pulley System: B-------O //// ////// | | | | | | ---O--- | B O = Pulley B = Block Find the acceleration of each block in terms of m1,m2 and g. Homework Equations F = ma The Attempt at a Solution I drew free body diagrams for each block...
  31. S

    How Do You Calculate Acceleration in a Pulley System with Different Masses?

    Homework Statement A 8.8 kg watermelon and a 7.7 kg pumpkin are attached to each other via a cord that wraps over a pulley, as shown. Friction is negligible everywhere in this system. Find the accelerations of the pumpkin and the watermelon. Specify magnitude and direction. Homework...
  32. D

    How to Determine the Upward Acceleration of a Mass in a Pulley System?

    Homework Statement Mass m1=26.1 kg is on a horizontal surface, connected to mass m2= 5.50 kg by a light string as shown. The pulley has negligible mass and no friction. A force of 197.7 N acts on m1 at an angle of 33.3 deg. The coefficient of kinetic friction between m1 and the surface is...
  33. L

    Solving for Speed of Blocks in Uniform Pulley System

    Homework Statement A pulley is a uniform cylindrical disk of mass m and radius r. The strings are massless and there is no friction. If the system is initially at rest, find the speed of the blocks (m1 and m2) after they have moved a distance d. m1----------0 **********l **********l...
  34. K

    Solve Pulley System Problem: Lift 52 kg Desk 2.32 m with 620 N

    Homework Statement A pulley system has an efficiency of 76.9%. The acceleration of gravity is 9.81 m/s^2. How much of the rope must be pulled in if a force of 620 N is needed to lift a 52 kg desk 2.32 m? Homework Equations Force = ma Work = force * distance The Attempt at a...
  35. B

    Solving Acceleration of 4kg Mass in Pulley System

    Homework Statement One end of a light inextensible string is attatched to a 4kg mass on a smooth horizontal table. The string passes over the edge of the table and to it's other end is attatched a light smooth pulley. Over this pulley passes another light inextensible string, with masses of...
  36. P

    Finding the masses of two blocks in a pulley system using work-energy theorem

    Two blocks with different mass are attached to either end of a light rope that passes over a light, frictionless pulley that is suspended from the ceiling. The masses are released from rest, and the more massive one starts to descend. After this block has descended a distance 1.00m , its speed...
  37. T

    Pulley system with Moment of Inertia

    A block of mass m1 = 2.05 kg and a block of mass m2 = 5.95 kg are connected by a massless string over a pulley in the shape of a solid disk having radius R = 0.250 m and mass M = 10.0 kg. These blocks are allowed to move on a fixed block-wedge of angle = 30.0°. The coefficient of kinetic...
  38. C

    Tricky Pulley System: How to Solve for Tension and Acceleration?

    Hi guys, this question is driving me up the wall because I always thought pulley system questions were easy and enjoyable to do, but this one refuses to cooperate! The question: Someone exerts a force F directly up on the axle of a pulley. Two objects, m1 of mass 1.2kg and m2 of mass 1.9kg...
  39. S

    What is the Coefficient of Kinetic Friction and Acceleration in a Pulley System?

    Block A has weight w_A and block B has weight w_B. Block A is positioned on the horizontal surface of a table. Block A is connected to a cord passing over an easily turned pulley that has Block B hanging down from the pulley. Once Block B is now set into downward motion, it descends at a...
  40. J

    Calculating Kinetic Energy Change for m1 in a Pulley System

    A m1 = 48.0 kg block and a m2 = 104.0 kg block are connected by a string as in Figure P8.36. The pulley is frictionless and of negligible mass. The coefficient of kinetic friction between the 48.0 kg block and incline is 0.250. Determine the change in the kinetic energy of the 48.0 kg block as...
  41. D

    Calculating Acceleration in Pulley System with m_1 = 5.0 kg and m_2 = 4.0 kg

    If m_1 = 5.0 \ kg \ and \ m_2 = 4.0 \ kg, what is the acceleration of m_2? I think the following equations describing the situation are correct: m_1a_1=T_1 - m_1g m_2a_2=T_2 - m_2g But I don't know how I can go about solving for a_2. Is there a relationship between the two tensions, and...
  42. A

    What Forces Affect the Motion in an Inclined Pulley System?

    I am having a problem finding the last part of this problem, and I'm not really sure if I did the first part right. The 1.0 kg physics book in Figure P8.38 is connected by a string to a 600 g coffee cup. The book is given a push up the slope and released with a speed of 3.0 m/s. The...
  43. J

    Tension Problem in a pulley system

    Tension Problem! Help please! I have a question that relates to a vertical/horizontal pulley system: i'll try drawing the diagram, hopefully someone can understand! O-------------|2.0kg| |...
  44. N

    Max Speed Glider w/Double Pulley System & Tub of Cement

    A glider is attached to a bathtub full of cement via a double pulley system, (the bath tub is hanging over a cliff). Assume the glider rests on a freely rolling cart. I wasn't sure of exactly how a double pulley works. The picture shows the one where the Glider is attached through the outer...
  45. B

    What is the mass of the bottom weight in this pulley system?

    The system is a 3kg weight on a table top attached to a string leading to a pulley at the end of the table. Attached to the string straight down is a weight with an unknown mass: ( )--------------- 3kg l...
  46. S

    Help With Pulley System: Calculating Angle Theta for Upper Rope

    I need help with this question (the picture is attached): A foot, mass of 4 kg, is suspended by a pulley system. The net traction force needs to pull straight out on the leg. What is the proper angle theta for the upper rope? I know that the system is frictionless so the tension in the...
  47. M

    How Can You Calculate Acceleration in a Two-Weight Pulley System?

    Hi, I'm working on a project involving a two-weight pulley system. The idea is to take two washers of slightly different masses and devise a method of determining a numerical value for the acceleration of gravity using the pulley. Basically the pulley slows down the effect of gravity, and I need...
  48. C

    Acceleration of a Pulley System: 100g & 120g Masses

    Okay...i did this lab where two different masses are on opposite ends of a string and hung over a pulley...how do i find the acceleration of the system if mass one is 100g and mass 2 is 120g. help! please...
  49. A

    Calculating Tension in Pulley System w/ Friction

    Two blocks A and B are connected via a pulley. http://img23.photobucket.com/albums/v68/AngelOfMusic/pulley.jpg They are initially at height h = 2 m from the ground. When block A hits the ground, it is moving at 3 m/s. For part a), I already determined the amount of frictional energy...
  50. P

    Acceleration of Pulley System with Masses m1 & m2

    There is a pulley system with 2 masses, m1 = 3.2kg and m2 = 1.2 kg the pulley is massless and frictionless. What I have to do is determine the acceleration of the system and the tension force in the rope. How would I find the acceleration?
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