Which of the following is an example of a class 1 lever?

A class 1 lever is characterized by having the fulcrum positioned between the input force and the output load. In the case of a crowbar, when the user applies force to one end of the lever (the handle), the fulcrum is located close to the load at the other end. This arrangement allows the mechanical advantage to lift or pry the load with relatively less effort, as the force is applied at a distance from the fulcrum.

Understanding the mechanics of levers is fundamental in structural collapse rescue, as these tools are often used to lift or move heavy debris. A wrench, for example, operates as a class 2 lever where the load (nut or bolt) is between the fulcrum (the point of rotation) and the input force applied through the handle. A pulley functions differently, utilizing a wheel and rope system to change the direction of force but does not fall under the lever classifications. An inclined plane is another form of simple machine used to reduce the effort needed to raise an object, but it also does not fit into the lever category. This context helps clarify why the crowbar is the correct answer for a class 1 lever.