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General Knowledge Practice Question 8

RequiredGeneral Knowledge · Question 8

The basic rule for safe following distance is one second per 10 feet of vehicle length under 40 mph, and:

• ANo additional time at higher speeds
• BAdd one extra second above 40 mph
• CSubtract one second above 40 mph
• DDouble the seconds above 40 mph

Correct answer: B. Add one extra second above 40 mph

Why: FMCSA's rule of thumb is one second per 10 feet of vehicle length below 40 mph, then add one additional second when traveling above 40 mph because reaction times stretch with speed.

How this question fits the General test

FMCSA requires General Knowledge competency under 49 CFR 383.111 because every CDL holder operates a heavy vehicle in mixed traffic where situational judgment, pre-trip discipline, and emergency response routinely separate a safe trip from a fatal one.

Study technique for this topic

Read the FMCSA Model CDL Manual Section 2 cover to cover, then re-read it focused on numbers — speeds, distances, weights, and pressures. Use the practice questions in this category to drill those numeric thresholds until you can answer without hesitation.

Related General practice questions

• Q65. When parking on a level surface, you should:
• Q14. Total stopping distance equals:
• Q27. When approaching a railroad crossing, you should look both ways at least:
• Q40. Engine brakes (Jake brakes) on wet roads should be:
• Q53. Reflective triangles after a stop on the road must be set out within:

Continue your CDL preparation

The General Knowledge portion of the CDL knowledge exam covers more than this single question. Use this site's full General Knowledge bank to drill every topic, then test yourself with one of our state-specific practice sets to confirm you are ready for the actual DMV exam in your state. Always check your state's CDL handbook for any local addenda before the test day.

If you are still building your overall CDL foundation, start with the General Knowledge bank — every CDL applicant must pass it — and then work outward to the endorsements you plan to add.