Basic Formula: 
E = (Fr x dr
) / (Fe x de)
x 100
or
E =Workout /
Workin x 100

E = Efficiency 
dr
= resistance
distance 
Fr
= resistance
force 

de =
effort distance 
Fe
= effort force 
Units: 
Work will always be a
distance unit times a force unit. It is usually a newton*meter (Nm) 
also known as a Joule (J) 

Distance unit: m
(meters) 

Force units: usually in N (newtons)
<Yes, in honor of Sir Isaac> 
These problems are not really
very hard to solve as long as you match the given numbers (usually using
their units) with the formula above. The hardest part of these
problems is figuring out what the resistance and effort forces are. Look
below for some quick references, then if you would like to check out some sample
problems, click on this link:
<efficiency sample problems> 
Determining the
resistances and efforts: 
Resistance Force: 
This will be the force which comes out of the
work being done. If you had to lift a 300N box, then the resistance
force would be the 300N. It is how much resistance the box had to
moving. 
Resistance Distance: 
This would be the total distance you
actually had to move that box, if you needed to ultimately lift it 2
meters, (no matter how you got it there, the ultimate distance it had to
go was 2.0 meters up). This would be your resistance distance. 
Effort Force 
This is how much effort you, the person (or
machine) doing work had to put into the movement in order to do work on
the object. If it took you 500N to move to that box, that would the
amount of effort you had to put in. 
Effort Distance 
This is how far you had to apply that
effort force. It could have been longer or shorter than the
resistance distance depending on the machine you are using. Either
way, it is how far you have apply the needed force. 
