Similarities: -- All three classes have a fulcrum (pivot). -- All three classes have a point where the effort force is applied. -- All three classes have a point where the load or resistance force is applied. -- If you can find a place to stand and a lever that's long enough, then you can move the Earth with a 1st or 2nd Class lever.
Differences: -- The mechanical advantage of a 1st Class lever can be greater than 1, equal to 1, or less than 1. -- The mechanical advantage of a 2nd Class lever is always more than 1 . -- The mechanical advantage of a 3rd Class lever is always less than 1 .
