Acrowbar is used as a lever. the effort force of 40 newtons moves 3 meters. the resistance force of 54 newtons moves 2 meters. what is the efficiency of the lever? 100% because energy must be conserved 90% 25% 18%

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Below is the solution:

Output work = 108 J. 
Input work = 120 J 

Efficiency = 108/120 = 9/10 = 90% 

(Energy can be converted to heat in friction at the fulcrum, or useless potential energy distorting the crowbar)

A medium or substance that transmits electric force without conduction; an insulator