Which examples are classified as first class levers?

First-class levers are defined by the position of the fulcrum being situated between the effort (the force applied) and the load (the resistance being moved). In this classification, the handy examples provided are the seesaw and the crowbar.

A seesaw operates by having the fulcrum fixed in the center while each person applies an effort on one end to lift the other end, effectively treating the center as the pivot point. This allows the seesaw to balance the load of the person sitting at the opposite end against the effort being used.

Similarly, a crowbar uses the fulcrum positioned between the applied force (when you push down on one end) and the load you're trying to lift (the object that the crowbar is prying up). The placement of the fulcrum allows for a significant mechanical advantage, making it easier to lift heavier items.

In the other choices, configurations do not fit the first-class lever model effectively. For instance, a wheelbarrow operates as a second-class lever because the load is positioned between the fulcrum (at the wheel) and the effort (applied at the handles). Scissors and pliers are also second-class levers as the fulcrum is located at