Stopping Distance Flashcards

All 5 cards in this deck

What is the stopping distance of a vehicle?

Stopping distance $=$ thinking distance $+$ braking distance.

For a given braking force, how does stopping distance change as the speed of a vehicle increases?

The greater the speed, the greater the stopping distance.

What are the steps to find stopping distance from a graph of thinking distance and braking distance against speed?
e.g. at $80$ km/h thinking distance is $15$ m and braking distance is $38$ m

1. Read the thinking distance at that speed: $15$ m
2. Read the braking distance at that speed: $38$ m
3. Add them: $15 + 38 = 53$ m

True or false? Doubling the speed of a car doubles its braking distance.

False. Braking distance increases much more than twofold (roughly with speed squared); it is the thinking distance that doubles.

Roughly how does a car's emergency stopping distance at $60$ mph compare with that at $30$ mph?

About three times greater (roughly $73$ m compared with $23$ m), because braking distance rises much faster than speed.