Test Applying Mechanical Reasoning Questions and Answers Flashcards

A Halligan bar is used to pry open a door. The firefighter applies force 18 inches from the fulcrum point at the door frame. What simple machine principle does this demonstrate?

Answer: First-class lever

A Halligan bar acting against a door frame with the contact point as the fulcrum and the firefighter applying force at the far end is a classic first-class lever.

Two firefighters carry a victim on a stretcher, each holding one end. How is the load distributed between them on level ground?

Answer: Each firefighter bears approximately half the total load

On level ground, each person supporting equal distances from the center of mass bears approximately half the load.

A hydraulic door ram forces entry. The device operates on which principle?

Answer: Pascal's Law — fluid pressure transmits force equally in all directions

Hydraulic door rams apply Pascal's Law — fluid pressure is transmitted equally in all directions, allowing a small pump to generate large output forces.

A firefighter uses a come-along attached to a vehicle to move it off a victim. If the come-along provides 4:1 mechanical advantage and the vehicle requires 2,000 pounds to move, how much force must the firefighter apply?

Answer: 500 lbs

Force equals load divided by mechanical advantage: 2,000 divided by 4 equals 500 pounds.

A ventilation fan is positioned at a doorway. As the blade diameter increases while RPM stays constant, what happens to airflow volume (CFM)?

Answer: CFM increases

Larger fan blades sweep a greater area per revolution, moving more air volume per unit time at the same rotational speed.

A roof ladder is hooked over a ridge and a firefighter hangs from it. What type of load does the hook experience?

Answer: Tensile load

The firefighter's weight pulls the hook downward, placing it under tension — a pulling or stretching force.