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Unformatted text preview: RYERSON UNIVERSITY DEPARTMENT OF PHYSICS LAB REPORT FOR PCS 211 SECTION 42 TITLE OF EXPERIMENT: Mechanical Advantage of Pulley EXPERIMENTERS: (Full names and ID’s) Abdi Abdirahman _500220713 Obaid Ansari– 500187730 Negar Honarmand-500122291 AUTHORS OF THIS REPORT: Obaid Ansari Negar Honarmand, and Abdi Abdirahman, EXPERIMENT PERFORMED ON (DATE): October 10 th , 2007 REPORT SUBMITTED ON (DATE): October 17 th , 2007 TA’S NAME: Mr. Don Objective and background Machines are used to make work easier. The reason is machines can decrease the force that the operator has to apply. Another reason is machine can increase the speed that the task is performed. Any device that can apply work by single force is called simple machine. “The work done is the product of the force and the distance. The amount of work required to achieve a set objective is constant; however the force required can be reduced provided the lesser force is applied over a longer distance. The ratio between the two forces is the mechanical advantage. ” (1) “A simple machine is so useful because it can exert an output force (or torque) which is greater that the input force (or torque). “The magnitude of the force multiplication is called the Mechanical Advantage . The Theoretical Mechanical Advantage or TMA for short is simply the ratio of the output force (load) by the ideal input force (ideal effort) :”( 3) TMA=F /F і ” But in real situation fraction always occurs which causes the fractional losses. “That is the input force (real effort) is always greater than the effort that would be required in an ideal frictionless case.” (3) Actual Mechanical Advantage or AMA for short is defined as AMA=F0/Fi “In the ideal case the input work equals the output work. F0d0=F і d і It is assumed that in the definition of work, the displacement and force have the same direction. Obviously, TMA=F /F і =d і /d “In real case, the input work equals the output work plus lost energy.” (3) Therefore, Wfr+F d =F і d і “Where Wfr is the work due to friction, the most common cause of energy loss.” (3) “Mechanical efficiency is essentially a measure of how much we get from the machine as...
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