Mechanical Advantage is the ratio of the force produced by a machine to the force applied to it,

It is used in assessing the performance of a machine.

Clearly the ratio ...

(Force Produced by machine)/(Applied force)

Should be more than 1

If MA = 1 then the machine is not useful and is just waste of money and space.

If MA < 1 then it is better to do work without the machine as it will need less force. 

We use the following formula to calculate the mechanical advantage of a lever  

MA = L ÷ E

Example 1: Calculate the mechanical advantage of a wheelbarrow that lifts a loads of 200 N with an effort of 100 N.

Solution: MA = 200 / 100 = 2

Note that there are no units of MA. 

Example 2: Calculate Load on a wheelbarrow if its distance from the fulcrum is 0.5 m and the distance of effort of 200 N required to move this load is 1 m.

Solution: Load x distance of Load to fulcrum= effort x distance of effort to fulcrum

Load x 0.5 m = 200 N x 1 m

Load = 400 N