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. H

    Complicated pulley system on an incline?

    Homework Statement Under the action of force P the constant acceleration of B is 6 m/s^2 up the incline as in figure. For the instant when B's velocity is 3 m/s up incline, what is the velocity of point C? How do I solve this using constraints? [/B] Homework Equations For a pulley system ΣT.v...
  2. D

    Change in the Kinetic Energy of a System

    The question is to find the change in kinetic energy of a system. the system in use is a pully system with a wooden block on a flat surface attached to a 100g mass. I have calculated force of friction between the block and desk, and using a ticker timer, I have individual speeds at every 0.1 of...
  3. 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...
  4. 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...
  5. 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...
  6. jalalapeno

    Finding Tension and theta in a pulley system

    What I've attempted to do is resolve vertically and horizontally: T1sin(30)+T2sinΘ+T2=9g T2cosΘ=T1cos30 After that... I'm completely stuck. Any help would be appreciated, I've spent so long on this I bet I'm just missing one simple thing. Thanks in advance
  7. SciencyBoi

    Three Pulley - two masses system.

    Homework Statement The given system is released from rest. Assuming no friction, mass-less pulleys and ideal strings; calculate the accelerations of the pulleys. Homework Equations Constraint equations. F=ma The Attempt at a Solution Taking the above assumptions; And applying constraints...
  8. C

    MHB What are the Variables Needed to Solve a Pulley System Problem?

    Two blocks are connected by a massless rope as shown below. The mass of the block on the table is 5.4 kg and the hanging mass is 2.1 kg. The table and the pulley are frictionless. I need to find acceleration, the tension of the rope, and the speed when mass 2 hits the floor when it starts from...
  9. H

    3 masses and an inclined pulley system

    Homework Statement The tension between the 6 kg and 4 kg object as=2.1m/s Fnet = 40N assume 0.4 kinetic friction coefficent Homework Equations T1- Fnet = mas The Attempt at a Solution acceleration is negative because the object is decelerating as it goes up the slope so T1-40N = 6(-2.1) T1 =...
  10. U

    Angular momentum of a pulley system

    Homework Statement it is given in the image i uploaded Homework Equations L→=r→ × p→[/B] The Attempt at a Solution If the angular momentum of a particle is the cross product of the position vector of the particle from the axis and its linear momentum, how can the angular momentum of m1 and...
  11. N

    What Is the Acceleration of Block B in a Two-Mass Pulley System?

    Homework Statement In the figure shown if the system is released from rest, acceleration of block B will be (a). g/2 (b). g/3 (c). 2g/3 (d). g/7 Homework Equations ma= F[net] taking the direction of motion as positive The Attempt at a Solution So my attempt was to first find tension in the...
  12. D

    Pulley system, calculate acceleration

    1. Homework Statement this is a pulley system, each masses are moving with acceleration with a1,a2,a3.. question) 1) How can i calculate the ratio a1:a2:a3 ? 2) How can i calculate the T(tenstion)? 2. Homework Equations a1,a2,a3: acceleration of each masses. g=10m/s2 weight of all pulleys...
  13. Deadawake

    Is Tension2 always smaller than Tension1 in a tension and pulley system?

    Homework Statement M = M There is another mass "m" attached to mass "M" with a rope There is an acceleration (clockwise) Does Tension2 smaller,bigger or equal to Tension1? Homework Equations F = ma The Attempt at a Solution So this is what I understand just by the logic: In any case -...
  14. J

    Perpendicular force pulley system

    i would like to know if the forces exerted by the load on pulley 1 and 2 are equal when the motor star running , or if in pulley 1 is exerted more force because the location of the load at the end of the lifting platform. The lifting platform only moves vertically, restricted by rails. What I...
  15. V

    Newton's laws of motion -- finding the velocity of a Block in a pulley system

    Homework Statement Determine the speed with which block B rises in figures if the end of cord at A is pulled down with a speed of 2ms^-1 Homework Equations Given Velocity downwards at A=2m/s The Attempt at a Solution Really stuck... Couldn't even start the question solving...I know all...
  16. V

    Newton's laws of motion -- pulley system

    Homework Statement In the situation given all surfaces are friction less pulley is ideal and steering is light. Find accn of block 2 Homework Equations Given F=mg/2 The Attempt at a Solution .[/B] Got answer as G/2 instead of G/4 ...(actual answer is g/4) Since F=mg/2 and block 1 is hanging...
  17. jasonpeng

    Why Is Tension Equal in a Frictionless and Massless Pulley System?

    I've got a problem with understanding the pulley system. In a basic pulley, if the force pulling M upwards is T, and the force pulling m upwards is also T, why is it that T is equal for both m & M? For some reason I feel inclined to believe that the T pulling m upwards is equal to the weight of...
  18. person123

    Exploring Pulley System Equilibrium: Solving for y when x Changes

    I was working on a pulley system as shown here: The mass on the right and left side is equivalent, and I am solving for when the system is in static equilibrium. Theta is the angle between the rope on either side of one of the pulleys. H and y are both measured from the original position of...
  19. B

    Pulley System on a Big Block: Solving for Acceleration with Zero Applied Force

    Homework Statement Find the accelaration of ##M_1## in the given system if ##F = 0##. Homework EquationsThe Attempt at a Solution [/B] ##x_3 -x_1 = k \iff \ddot x_3 = \ddot x_1## and ##h - y_3 + x_3 - x_2 = l \iff \ddot y_3 + \ddot x_2 = \ddot x_3 \qquad (*)## h is the height of block...
  20. S

    Kinetics of System Particle/ Pulley system with masses and i

    I can't seem to solve it, considering inertia can someone please solve it, both of the following question in the given picture. I would be very much thankful.
  21. K

    Natural frequency of pulley system

    Homework Statement https://www.physicsforums.com/attachments/197474 Homework Equations 3. The Attempt at a Solution [/B] ma + kx = 0 I know how to do it if the spring is in the middle of the pulley, not using energy method. by the free body diagram. But I am stuck at this. [Updated: I know...
  22. Alok

    How pulley diameter affects forces?

    Whether the diameter/radius of pulley affects the force required in lifting a weight?
  23. jerryd87

    Three weights and two pulley system

    Homework Statement The goal is to find the tension in the strings and acceleration of each block. M1=8 kg, m2=1 kg, and m3= 2 kg. This is a study problem so not really homework but I am having trouble finding anything quite like this problem. Homework Equations m1g-t1=m1a1 t2-m2g=m2a2...
  24. C

    Find acceleration of a pulley system

    Homework Statement A pulley of radius, R and moment of inertia, I=2MR^2 is mounted on an axle with negligible friction. Block A, with a mass M, and Block B, with a mass of 3M, are attached to a light string that passes over the pulley. Assuming that the string doesn't slip on the pulley, Answer...
  25. L

    Why Ignore Tension In Pulley and Work Energy Problems?

    A pulley and block system is a favorite type of system for analysis when considering work-energy problems in beginning dynamics. It's commonly recommended that the best approach to the system is to write an equation for the whole system, while ignoring the work done by cables/ropes and focusing...
  26. B

    Relations between torque for system of pulleys

    Homework Statement In an attempt to find a transfer function of the system, I need to come up with equations that I can use to solve for unknowns. See the attached image to see the diagram of the pulley system. J is the moment of inertia, r is the radius. The smaller radius on pulley 2 is r1...
  27. S

    Pulley system and energy conservation?

    Homework Statement [/B] Two blocks are connected by a string that passes over a massless, frictionless pulley, as shown in the figure. Block A, with a mass mA = 4.00 kg, rests on a ramp measuring 3.0 m vertically and 4.0 m horizontally. Block B hangs vertically below the pulley. Note that you...
  28. J

    Newton's Second Law -- Accelerations in a pulley system

    Homework Statement A 20-kg block with a pulley attached slides along a frictionless ledge. It is connected by a massless string to a 5.0-kg block via the arrangement shown in Figure. (a) draw complete free body diagrams for the masses and Find (b) the acceleration of each block and (c) the...
  29. P

    Calculate Tube Uncoiler Reel Acceleration | P-J

    Hello, I'm making a tube uncoiler and I'm trying to find the acceleration of the tube at the reel (a3) can someone help me with this. kind regards, P-J
  30. Kevin de Oliveira

    Static Equilibrium: Why Does Changing Pulley Position Affect Relative Angles?

    I have a 3 pulley system statically balanced hanging weights at a determined relative angle (we are taking into account friction). If I change the position of one pulley, angles will remain the same. However, if I have a 4 pulley system, at the same conditions, changing one's position will...
  31. J

    "How Fr=Ialpha Works in a Pulley w/ Mass

    Homework Statement How does Fr=Ialpha work and how is it applied to a pulley with one mass attatched? Homework Equations F * r = I * alpha I = moment of inertia The Attempt at a Solution I'm assuming F would be the tension of the pulley with the string. But how does that equation work? can...
  32. R

    Solving for Velocity on a Pulley System

    Homework Statement In the picture below. Homework Equations Velocity on a pulley = (velocity on left rope + velocity right rope)/2 Pulley A and C have 0 velocity. The Attempt at a Solution By inspection the right sided rope on pulley A is 120 mm/s going up. After that is when I get confused...
  33. ikihi

    How Do You Calculate the Angular Motion of a Pulley System?

    Homework Statement Consider a pulley with a mass-less cord attached to its edge. The rope hangs a distance of d= 2.50 m below the bottom of the pulley. Attached to the end of this cord is a block with mass 3.00 kg. There is also an electric motor attached to the pulley which supplies a torque...
  34. ikihi

    Mass and pulley system (Rotational Dynamics)

    Homework Statement Consider a pulley with a mass-less cord attached to its edge. The rope hangs a distance of d= 2.50 m below the bottom of the pulley. Attached to the end of this cord is a block with mass 3.00 kg. There is also an electric motor attached to the pulley which supplies a torque...
  35. S

    Acceleration of a Mass in a Pulley System

    The block 1 of m1 sheets of mass on an inclined plane without friction at an angle θ to the horizontal. One end of a non-extendable rope with no mass is attached to lock 1. The chain is wound around a non-frictionally mobile pulley P of negligible mass and is also connected to the wall at the...
  36. Z

    Determine the force in a pulley system

    Homework Statement If A has a mass of 300kg, determine the mass of B if the system in figure P4-28 is to be in balance. (What I couldn't understand is the 2Tb in the answer.) Homework Equations ΣFy=0[/B]The Attempt at a Solution Since the pulley on top is connected with two pulley at the...
  37. Shashank Holla

    Acceleration due to *equal* weights on pulley system

    Homework Statement [/B] Which of the following is correct? 1. The acceleration of pulley B is g/11 downwards 2. The acc. of pulley C is g/11 upwards 3. Tension in string passing over pulley A is 12.46g N 4. Tension in string passing over pulley A is 10g N Homework Equations F=m.a[/B]The...
  38. M

    What is the Time to Pivot the Rod with a Spinning Disk?

    Homework Statement A rod of length L = 20 m and mass m = 50 kg juts out perpendicular to a wall. The rod is designed to pivot vertically about the point where it intersects the wall. A massless pulley is affixed to the wall a height h = 10 m above the rod. A cable is attached to the rod a...
  39. W

    Conservation of Momentum: Pulley System

    Homework Statement Block A (of mass MA) rests on a frictionless horizontal table. It is connected via a light string to block B (of mass MB) hanging over the edge of the table. The pulley itself, a solid disc, has non-negligible mass MC. The light string does not slip over the pulley. What is...
  40. 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...
  41. 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...
  42. 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...
  43. 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...
  44. 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...
  45. 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...
  46. 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...
  47. 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...
  48. 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...
  49. euphorik

    Help me move a floating bridge 90 degrees w/o getting wet

    Hello! I was hoping someone here could help me solve a real world problem. So my university pool has something called a bulkhead, which is basically a bridge that floats above the water so that people can walk across the shorter dimension of the rectangular pool (50 meters long, 25 yards wide)...
  50. 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...
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