There are three arms of equal length fitted with tensioned springs in between the handle and fulcrum at different distances. Press the springs one by one with the help of handle and observe.

What did you observe? 
Different amount of energy is spent for each spring.

The science behind it :
This type of arrangement where load is located in between the fulcrum and the effort is called the second order lever. Here the mechanical advantage is varying with the length between the fulcrum and spring.