SIMPLE MACHINE PROBLEMS II SOLUTIONS

# SIMPLE MACHINE PROBLEMS II SOLUTIONS - SIMPLE MACHINE...

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SIMPLE MACHINE PROBLEMS II SOLUTIONS 1) a) From the diagram, the last pulley provides the support for the load. The tension in the supporting cables is 4 4 8 E E L E L L E + = = = 8 . Hence, the mechanical advantage of the pulley system is 8. b) Assuming no friction in the pulley system, then ( )( ) ( )( ) F F F F F output input input input input = = = = 8 40 9 8 8 1 8 40 9 8 49 . . N N . c) The effort was increased from 49 N to 63 N which implies the extra effort must be due to overcoming friction. Hence, the frictional force must have been . ( ) 63 49 N = 14 N d) The AMA of the pulley system is ( )( ) 40 98 63 56 9 . = . The IMA of the pulley system is 8. Hence, the efficiency of the pulley system is ( )( ) ε ε = × = × AMA IMA 100% 56 9 8 100% 78% ε . 2) a) For a second class lever, the fulcrum is at one end of the lever arm. Furthermore, the input is at the other end. Hence, . Since these quantities are positive, non–zero values, then d d input output > d d d d d d IMA d d input output input output output output input output > > = 1 > .

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