Levers Mechanical Advantage and Disadvantage

The efficacy of a force in relation to a lever is dependent upon two factors, i.e. the force exerted (W) or (E), and its perpendicular distance from the fulcrum (weight's arm or effort's arm). 

The product of these two factors is known as the Moment of Force (or torque). When weights and effort arm are of equal length an effort of a magnitude equal to that of the weight will be required to lift it.

 No advantage is gained but the machine is useful for measuring weights as, for ex ample, in the common balance.

If, however, the length of the effort's arm exceeds that of the weight's arm, less effort will be required to achieve a similar result and an advantage will be gained by the use of the lever.

 This is known as a

 Mechanical Advantage, and it is obtained in levers of the First Order when the fulcrum is nearer to the weight than to the effort, and in all levers of the 2nd Order. It is never obtained in levers of the 3rd Order.

 the ratio of the (W) weight to the  (E) effort, expressed thus:

              W    ( Mechanical Advantage)

M.A. =  ―   

              E      

              

Conversely, in cases in which the weight arm exceeds the effort arm, a condition of

Mechanical Disadvantage occurs, as in levers of the 1st Order,

 when the fulcrum is nearer to the effort than to the weight and in all levers of the 3rd Order

 For further information click on link given below↓↓↓↓↓↓↓

⏩Examples of all three Orders of levers 
⏩Lever at Home and at Work