Speed and Stopping Distances Flashcards
6 cards from real DVSA practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Speed and Stopping Distances flashcards as text
Why are 20 mph zones increasingly common near schools?
Answer: Because the risk of a pedestrian fatality drops dramatically — from about 80% at 40 mph to roughly 10% at 20 mph
At 20 mph, a pedestrian has approximately a 90% chance of surviving a collision. At 30 mph this drops to around 80%, and at 40 mph a pedestrian has roughly a 10% chance of survival. The dramatic improvement in survivability at 20 mph makes it particularly appropriate near schools where children may run into the road.
What effect does a loose or gravel road surface have on braking distance?
Answer: It significantly increases braking distance because tyres have less grip on loose material
Loose surfaces such as gravel, mud, wet leaves, or sand significantly reduce tyre grip, increasing braking distance. ABS brakes may also be less effective on loose surfaces. Reduce speed and brake gently to maintain control.
How does the gradient of the road affect overall stopping distance?
Answer: Uphill reduces stopping distance; downhill increases it, because gravity assists or opposes braking
When going uphill, gravity helps slow the vehicle, reducing braking distance. Downhill, gravity works against braking, increasing braking distance. On a steep downhill slope, you should use a lower gear to help control speed and avoid overheating your brakes.
At 50 mph, what is the approximate overall stopping distance?
Answer: 53 metres (175 feet)
At 50 mph, the overall stopping distance is approximately 53 metres (175 feet) — about 13 car lengths. This comprises 15 metres thinking distance and 38 metres braking distance.
How do prescription medications potentially affect stopping distance?
Answer: Some can cause drowsiness or slow reactions, increasing thinking distance
Many prescription medications, including antihistamines, painkillers, and some antidepressants, can cause drowsiness, blurred vision, or slowed reactions. This increases your thinking distance. Always read the label and ask your doctor or pharmacist if it is safe to drive while taking medication.
What happens to stopping distance if you double your speed from 30 mph to 60 mph?
Answer: It approximately triples from 23 to 73 metres
Doubling your speed from 30 to 60 mph roughly triples the overall stopping distance from 23 metres to 73 metres. The thinking distance doubles (9 to 18 metres), but the braking distance roughly quadruples (14 to 55 metres). The combined effect is approximately a tripling.