FCTC Mechanical Reasoning Principles Questions and Answers 3

Question 1

A pulley system is used to raise a 300-pound victim. If the system has a mechanical advantage of 3, how much force must the rescuer apply (ignoring friction)?

Accepted Answer

100 lbs

Answer

150 lbs

Answer

300 lbs

Answer

900 lbs

Question 2

Which simple machine does a firefighter use when sliding a victim down a stairway on a rescue sled?

Accepted Answer

Inclined plane

Answer

Lever

Answer

Wheel and axle

Answer

Pulley

Question 3

In a compound pulley system, if you must pull 6 feet of rope to raise a load by 1 foot, what is the mechanical advantage?

Accepted Answer

6

Answer

1

Answer

3

Answer

12

Question 4

A fire pump impeller spins faster when driven by a larger sprocket connected by a chain to a smaller sprocket on the impeller shaft. Which sprocket is the driver?

Accepted Answer

The larger sprocket — it drives at lower RPM but speeds up the smaller driven sprocket

Answer

The smaller sprocket — it drives at higher RPM

Answer

Both sprockets rotate at the same speed

Answer

The impeller speed is unaffected by sprocket size

Question 5

What is the main advantage of a worm gear mechanism used in some fire apparatus equipment?

Accepted Answer

Large mechanical advantage combined with a self-locking ability

Answer

Very high speed transmission

Answer

Low torque output

Answer

Ability to change direction of rotation freely in both directions

Question 6

A fire department come-along (ratchet lever hoist) is rated at 2,000 pounds. The device uses which mechanical principle to achieve this rating?

Accepted Answer

Ratchet and pawl combined with a lever arm to provide mechanical advantage

Answer

Hydraulic force multiplication

Answer

Electromagnetic braking

Answer

Pneumatic pressure amplification