Controlling Speed — CDL General Knowledge Practice Test

This CDL General Knowledge Controlling Speed practice set has 30 practice questions based on the official exam materials, each with an instant explanation. You need 80% on the real CDL General Knowledge knowledge test to pass.

Sample questions

Three questions from the Controlling Speed bank with the correct answer and an explanation. The practice quiz above draws 30 questions at random from the same bank.

1. According to the manual, driving too fast is a major cause of what?

   • Fatal crashes — Correct answer
   • Lower fuel economy
   • Faster tire wear
   • Engine overheating

   Explanation: Driving too fast is a major cause of fatal crashes; you must adjust your speed for traction, curves, visibility, traffic and hills. English term: controlling speed（控制车速 / control de la velocidad）.

   Handbook: Controlling Speed — Why Speed Matters

2. What three distances add up to total stopping distance?

   • Perception distance + reaction distance + braking distance — Correct answer
   • Following distance + reaction distance + braking distance
   • Perception distance + braking distance + skid distance
   • Reaction distance + braking distance + coasting distance

   Explanation: Total stopping distance = perception distance + reaction distance + braking distance. English terms: total stopping distance（总停车距离 / distancia total de detención）, perception distance（感知距离）, reaction distance（反应距离）, braking distance（制动距离）.

   Handbook: Controlling Speed — Stopping Distance

3. What is perception distance?

   • The distance traveled from when your eyes see a hazard until your brain recognizes it — Correct answer
   • The distance traveled while you are physically pressing the brake
   • The distance traveled before you physically hit the brakes
   • The safe gap you keep behind the vehicle ahead

   Explanation: Perception distance is how far your vehicle travels from the time your eyes see a hazard until your brain recognizes it; the average alert driver takes about 1¾ seconds, or 142 feet at 55 mph. English term: perception distance（感知距离 / distancia de percepción）.

   Handbook: Controlling Speed — Stopping Distance