FCTC Mechanical Reasoning Principles 2

Question 1

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

Accepted Answer

Pressure increases by a factor of 4

Answer

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

Question 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?

Accepted Answer

Pascal's Law

Answer

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.

Question 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?

Accepted Answer

8

Answer

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

Question 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?

Accepted Answer

Movable pulley — 2:1

Answer

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

Question 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?

Accepted Answer

Spur gear

Answer

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.

FCTC Test Practice Test

FCTC Test Practice Test

FCTC Mechanical Reasoning Principles 2