Emergency Vehicle Dynamics & Physics Flashcards

When a driver doubles their speed, how does stopping distance change?

Answer: It quadruples (4×)

Stopping distance is proportional to the square of speed, so doubling speed quadruples the stopping distance.

What is the correct braking technique for a vehicle equipped with anti-lock brakes (ABS) during an emergency stop?

Answer: Apply firm, continuous pressure and hold

ABS-equipped vehicles require firm, sustained pedal pressure; the system automatically modulates brake force to prevent wheel lockup.

Which single factor has the greatest impact on total stopping distance at highway speeds?

Answer: Vehicle speed

Since stopping distance increases with the square of speed, vehicle speed has an exponential—not linear—effect on total stopping distance.

What causes brake fade during prolonged heavy braking?

Answer: Overheating of brake components reducing friction effectiveness

Brake fade occurs when excessive heat builds up in the braking system, lowering the friction coefficient between pads and rotors.

How does a heavier vehicle load affect stopping distance?

Answer: Increases stopping distance due to greater kinetic energy

A heavier load increases the vehicle's kinetic energy, which requires more distance and braking force to dissipate.

What is the recommended technique to prevent brake fade when descending a steep grade?

Answer: Use engine braking by downshifting and apply brakes intermittently

Engine braking reduces the workload on friction brakes, preventing heat buildup and brake fade on long descents.

At what approximate speed does hydroplaning typically begin on a wet road surface?

Answer: 35 mph

Hydroplaning can begin at speeds as low as 35 mph when tires lose contact with pavement due to a film of water.