Firefighter Practice Exam

How much resistance would a 75-pound ladder present when lifted by firefighters applying leverage at a point 10 feet from an anchor?

1. 37.5 pounds of resistance

2. 75 pounds of resistance

3. 127.8 pounds of resistance

4. 93.75 pounds of resistance

The correct answer is: 93.75 pounds of resistance

When considering the resistance presented by a ladder when lifted using leverage, the distance from the lifting point to the anchor plays a critical role in determining how much effort is needed. In this scenario, firefighters are lifting a 75-pound ladder by applying leverage at a point 10 feet from an anchor point. To find the resistance encountered, you can apply the principle of torque, which involves the concepts of load and lever arm distance. The effort required to lift the ladder is inversely proportional to the distance from where the firefighters are applying that effort to the anchor. In a practical sense, the farther away they are from the anchor, the less lifting effort (or resistance) they will feel due to the mechanical advantage provided by the lever. Using the formula for calculating resistance, the actual resistance felt can be determined by comparing the full weight of the ladder to the distances involved. When you calculate the lever effect of applying force at 10 feet versus just lifting the entire weight directly (without leverage), the resistance effectively felt reduces due to this mechanical advantage. In this instance, as per the calculations, the resistance comes out to be 93.75 pounds, indicating that the leverage applied at that distance significantly decreases the perceived weight being lifted directly by the firefighters.