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Mechanical Reasoning Principles Flashcards

6 cards from real FCTC practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 6 Mechanical Reasoning Principles flashcards as text

  1. A fire pump uses a centrifugal impeller. What happens to water pressure output if the pump speed is doubled?

    Answer: Pressure increases by a factor of 4

    For centrifugal pumps, pressure (head) increases with the square of the speed. Doubling speed quadruples pressure output.

  2. A hydraulic spreader (Jaws of Life) uses fluid to generate force. Which principle explains how a small force on the input cylinder creates a larger force on the output cylinder?

    Answer: Pascal's Law

    Pascal's Law states that pressure applied to a confined fluid is transmitted equally in all directions. A larger output piston area multiplies the force.

  3. A firefighter uses a Halligan bar as a class 1 lever to force a door. If the fulcrum is 3 inches from the load end and the firefighter applies force at 24 inches from the fulcrum, what is the mechanical advantage?

    Answer: 8

    Mechanical Advantage = Effort Arm ÷ Load Arm = 24 ÷ 3 = 8.

  4. What type of pulley system would a firefighter use to lift a victim from a below-grade confined space with the greatest mechanical advantage using a single movable pulley?

    Answer: Movable pulley — 2:1

    A single movable pulley creates a 2:1 mechanical advantage, halving the effort required to lift the load.

  5. Which type of gear arrangement is used when two gears mesh together with teeth, and turning the first gear clockwise causes the second gear to turn counterclockwise?

    Answer: Spur gear

    Spur gears are the simplest meshing gears — when two spur gears mesh, they rotate in opposite directions. The driving gear turns clockwise, the driven gear turns counterclockwise.

  6. A fire hose nozzle is attached at the end of 100 feet of hose. What happens to water velocity as the water passes through the nozzle opening (assuming nozzle diameter is smaller than hose diameter)?

    Answer: Velocity increases

    According to the continuity equation (conservation of mass), when cross-sectional area decreases, fluid velocity must increase to maintain the same flow rate.