Ch. 4 · Pre-Drive Conduct

When speed doubles, braking distance, centrifugal force, and impact force all double.

[True / False · Hard]

Answer: ✕ False

Explanation

The text clearly states: "When speed doubles, braking distance, the force that causes a vehicle to skid or roll over on curves, and the impact force related to the severity of traffic accidents do not double—they quadruple." These forces are proportional to the square of the speed, so quadrupling is correct.

Driving school curriculumStage 2 – Topic 5: Human capability and driving

Hikari
Hikari
Double the speed, double the force — sounds logical.
Misaki
Misaki
That's false. When speed doubles, braking distance, centrifugal force, and impact force don't just double — they quadruple.
Hikari
Hikari
Wait, quadruple? That's way more than I thought!
Misaki
Misaki
Exactly. These forces grow with the square of your speed, so even small increases in speed create huge jumps in danger.

Source: Ch. 4 Pre-Drive Conduct · Section (第５節 安全運転に必要な知識など) · ２ 自動車に働く自然の力 (４) 速度の影響 - 速度が２倍になれば、制動距離、カーブで車の横滑りや転倒をさせようとする力、交通事故の大きさに関係する衝撃力は、２倍になるのではなく、４倍になります。

🤖 Dig deeper with AI

Send this question's context to ChatGPT for a richer explanation. The prompt also asks the AI to point you back to this chapter's practice quiz.

🚀 Ask ChatGPT

If the button doesn't open ChatGPT, tap Copy and paste it into Claude, Gemini, or any other LLM you prefer. On a free plan, Claude (claude.ai) tends to produce more accurate explanations that respect this site's content.

← Back to all Ch. 4 questions

See the glossary for definitions of key terms.

Source content excerpted from the NPA “Rules of the Road” instructional manual, in the public domain under Japanese Copyright Act Article 13(2). Explanations are AI-assisted and copyrighted by the MenkyoQuest editorial team.