Question

What are uses of the first class levers?

Answer 1

seesaw
pliers
crow bar 
tongs
scissors
can opener

First class levers always change the direction of the input force, unlike second and third class levers. The fulcrum is always in between the input force and the out put force. First class levers can multiply the force or the distance depending on where the fulcrum is placed and where the forces are applied. A first class lever can be something as simple as a crow bar or a pair of scissors. 

Answer 2

Levers make it easier to lift heavy materials, remove tight objects and cut items. A first-class lever has a fulcrum in the center, between the effort -- or force -- and the load, the object being moved or lifted.