FCTC Mechanical Reasoning Principles 3

Question 1

A fire apparatus wheel lug nut must be tightened to 450 ft-lbs of torque. A mechanic uses a wrench 18 inches long. How much force (in lbs) must be applied to the end of the wrench?

Accepted Answer

300 lbs

Answer

250 lbs

Answer

350 lbs

Answer

400 lbs

Question 2

A fire truck uses an air brake system. When the driver presses the brake pedal, compressed air pressure is _____ to the service chambers to apply the brakes.

Accepted Answer

Directed (increased) in the brake chambers

Answer

Released from the brake chambers

Answer

Maintained at a constant level

Answer

Reversed in direction

Question 3

What is the mechanical purpose of a fire pump's relief valve?

Accepted Answer

Prevent excessive pressure buildup that could damage hoses or injure firefighters

Answer

Increase maximum flow rate

Answer

Maintain constant RPM

Answer

Filter debris from the water supply

Question 4

A firefighter needs to move a 500-lb object using a ramp. The ramp is 10 feet long and 2.5 feet high. What is the mechanical advantage of the ramp?

Accepted Answer

4

Answer

2

Answer

3

Answer

5

Question 5

A fire engine's V-belt drives the alternator. If the engine crankshaft pulley is 8 inches in diameter and the alternator pulley is 2 inches in diameter, how much faster does the alternator spin than the crankshaft?

Accepted Answer

4×

Answer

2×

Answer

6×

Answer

8×

Question 6

Which simple machine principle is applied when a firefighter uses a wedge to prop open a door?

Accepted Answer

Inclined plane — a wedge is a double inclined plane

Answer

Lever

Answer

Pulley

Answer

Wheel and axle