Block and Tackle Pulley Systems and Pulley Advantage, 1M20.11

Topic and Concept:

• Work and Energy, [:WorkEnergy#SimpleMachines: 1M20. Simple Machines]

Location:

• Floor Item [:MechanicsCabinet:Mechanic (ME)]

• There is another system within the physics museum

  attachment:BlockTackle03-400.jpg

Abstract: An assortment of four different pulley systems is suspended from a frame showing the principle of mechanical advantage.

Important Setup Notes:

• N/A

Setup and Procedure:

1. Position the rack so that the audience has a good view of all of the pulley systems.

Cautions, Warnings, or Safety Concerns:

• N/A

Discussion:

Pulleys are mechanisms compost of one or more wheels and a rope threaded though them and attached to some heavy object so that it can be lifted without much effort. Showing the principle of mechanical advantage. The rotation of the pulleys change the direction of an applied force and they can even reduce the force needed to lift a heavy weight, like a piano. Pulleys systems are common used in constructions. This systems of one to four pulley systems, a 1 to 1, 1 to 2, 1 to 4, and 1 to 6. Each doubling, doubles the amount of rope one has to pull to lift that weight to the same height, say lift a 1lb weight to a height of 1 ft.

Example:

In order to lift the 1lb weight W you have to apply a force of F on the rope equal to the weight W. The rope is now under a tension T equal to the force F. To lift this weight a distance of H=1 ft you will have to pull in a length L= H=1 ft of the rope. The mechanical advantage M is one: M=W/F=1.

Videos:

• [https://www.youtube.com/user/LectureDemostrations/videos?view=1 Lecture Demonstration's Youtube Channel]

References:

• [http://en.wikipedia.org/wiki/Block_and_tackle Block and Tackle - Wikipedia]

• [http://www.physics.wisc.edu/museum/Exhibits-1/Mechanics/Pulleys/index_Pulleys.html L.R. Ingersoll Physics Museum]

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