Let a machine overcome a load L by the application of an effort E. In time t, let the displacement of effort of dE ad the displacement of load be dL.
Work input =Effort× displacement of effort
=E×dE
Work output =Load× displacement of load
=L×dL
Efficiency=Work outputWork input
=L×dLE×dE=LE×dLdE
=LE×1dE/dL
But Load(L)Effort(E)=M.A.
and dEdL=V.R.
∴Efficiency η=M.A.V.R. or M.A.=V.R.×η
Thus, the mechanical advantage of a machine is equal to the product of its efficiency and Velocity Ratio.