Safe driving requires a clear understanding of how thinking and braking distances combine … — UK Driving Theory Test

Safe driving requires a clear understanding of how thinking and braking distances combine under dry road conditions. Match each vehicle speed and distance component to its official value as stated in The Highway Code.

$20\text{ mph}$ ( $32\text{ km/h}$ ) — Total stopping distance $12\text{ metres}$ ( $40\text{ feet}$ )
$40\text{ mph}$ ( $64\text{ km/h}$ ) — Braking distance $24\text{ metres}$ ( $80\text{ feet}$ )
$60\text{ mph}$ ( $96\text{ km/h}$ ) — Total stopping distance $73\text{ metres}$ ( $240\text{ feet}$ )
$70\text{ mph}$ ( $112\text{ km/h}$ ) — Thinking distance $21\text{ metres}$ ( $70\text{ feet}$ )

Answer

20\text{ mph}

Total stopping distance matches

12\text{ metres}

(

40\text{ feet}

);

40\text{ mph}

Braking distance matches

24\text{ metres}

(

80\text{ feet}

);

60\text{ mph}

Total stopping distance matches

73\text{ metres}

(

240\text{ feet}

);

70\text{ mph}

Thinking distance matches

21\text{ metres}

(

70\text{ feet}

According to The Highway Code, stopping distances on dry surfaces consist of thinking distance plus braking distance. At

20\text{ mph}

, the overall stopping distance is

12\text{ m}

(

40\text{ ft}

). At

40\text{ mph}

, the braking component alone is

24\text{ m}

(

80\text{ ft}

). At

60\text{ mph}

, the total stopping distance reaches

73\text{ m}

(

240\text{ ft}

). At

70\text{ mph}

, the thinking distance component is

21\text{ m}

(

70\text{ ft}

Step-by-Step Solution

Determine the total stopping distance for a vehicle travelling at

20\text{ mph}

12\text{ metres}

(

40\text{ feet}

)

20\text{ mph}

, thinking distance is

6\text{ metres}

(

20\text{ feet}

) and braking distance is

6\text{ metres}

(

20\text{ feet}

), summing to

12\text{ metres}

(

40\text{ feet}

Isolate the braking distance component for a vehicle travelling at

40\text{ mph}

24\text{ metres}

(

80\text{ feet}

)

40\text{ mph}

, thinking distance is

12\text{ metres}

while the vehicle travels

24\text{ metres}

under braking before coming to a halt.

Calculate the total stopping distance for a vehicle travelling at

60\text{ mph}

73\text{ metres}

(

240\text{ feet}

)

60\text{ mph}

, thinking distance is

18\text{ metres}

(

60\text{ feet}

) and braking distance is

55\text{ metres}

(

180\text{ feet}

), giving a combined total of

73\text{ metres}

(

240\text{ feet}

Identify the reaction/thinking distance component for a vehicle travelling at

70\text{ mph}

21\text{ metres}

(

70\text{ feet}

)

Thinking distance increases linearly with speed; at

70\text{ mph}

, reaction distance equals

21\text{ metres}

(

70\text{ feet}

Key Concept

Total Stopping Distance equals Thinking Distance plus Braking Distance under standard dry road conditions.

Estimated Time:1m 15s

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