SUMMARYNow for a brief summary of levers:Levers are machines because they help you to doyour work. They help by changing the size,direction, or speed of the force you apply.There are three classes of levers. They differprimarily in the relative points where effort isapplied, where the resistance is overcome, andwhere the fulcrum is located.First-class levers have the effort and the resistanceon opposite sides of the fulcrum, and effort andresistance move in opposite directions.Second-class levers have the effort and theresistance on the same side of the fulrum butthe effort is farther from the fulcrum than is theresistance. Both effort and resistance move inthe same direction.Third-class levers have the effort applied on thesame side of the fulcrum as the resistance butthe effort is applied between the resistance andthe fulcrum, and both effort and resistancemove in the same direction.First- and second-class levers magnify the amountof effort exerted and decrease the speed ofeffort. First-class and third-class levers magnifythe distance and the speed of the effort exertedand decrease its magnitude.The same general formula applies to all three typesof levers:LR— = —lEMechanical advantage (M.A.) is an expression ofthe ratio of the applied force and the resistance.It may be written:1-8
Integrated Publishing, Inc. - A (SDVOSB) Service Disabled Veteran Owned Small Business