9Know your speed limits – fill in the missing speeds ?
10Lesson objective: know your stopping distances Lesson outcomes:State what is the meaning of braking distance, thinking distance and stopping distance.Describe what can affect the braking distance, thinking distance and stopping distance.Explain – aquaplaningECA
14Well, you need to pass your test first Well, you need to pass your test first! A written exam and a practical exam
15 Stopping distances How long does it take a moving vehicle to stop? Thinking distance is the distance a car travels before the brakes are applied.The stopping distance is the sum of the thinking distance and the braking distance.Braking distance is the distance a car travels whilst the brakes are being applied.Braking distanceThinking distanceStopping distanceStopping distance = thinking distance + braking distance
16Thinking distance Braking distance The distance the car travels in the split second between a hazard appearing and the driver applying the brakesBraking distanceThe distance the car travels during its deceleration, whilst the brakes are being applied
17The total stopping distance = thinking distance + breaking distance 30mph9m +14m = 6 car lengths50mph15m m = 13 car lengths21m m = 24 car lengths70mph
24It is affected by 4 main factors: Braking distanceIt is affected by 4 main factors:How fast you are goingThe mass (or load) of the vehicleIf the car is poorly maintained – brakes and tyres (groves in tyres – 1.6mm deep)The grip of the road surface – on a wet road you can skid twice as long
25Why is this illegal? How will this affect your stopping distance? Bald tyres make stopping distances shorter on dry roads, WhyA bald tyre has more contact on the road and therefore more friction!
26What about aquaplaning ? On a wet road, tyre treads channel water out from between the tyre and the roadRemoving the water away from the tyre and the road
27What about aquaplaning ? Bald tyres allow a thin layer of water to stay between the tyre and the road, reducing frictionWhy do racing drivers change their tyres when it is wet?
28Can you match up the words with their definitions? Stopping distanceFrictionThinking distanceBraking distanceOne of forces the road exerts on the tyres as the car is stopping.The distance a car travels whilst it is braking.The distance a car travels before the brakes are applied.The sum of thinking distance and the braking distance.
29What factors affect braking and thinking distance? Braking distanceSpeed of carSpeed of carDrugs and alcoholRoad conditionsCondition of tyresTirednessMedicationCondition of brakesMedicationCondition of tyresSpeed of carDrugs and alcoholRoad conditionsTirednessCondition of brakes
30Medication, drugs/alcohol, speed of car, tiredness Braking car question:A car is moving along an open road. Suddenly, a sheep walks into the road.What do we call the distance the car travels before the driver puts their foot on the brakes?Name one factor that could increase the distance the car travels in this time.The braking distance is 35m for the car. If the stopping distance is 50m, how far did the car travel before the driver put their foot on the brakes?Thinking distanceMedication, drugs/alcohol, speed of car, tirednessThinking distance = Stopping distance – braking distance= 50m – 35m= 15m
32Stopping a car… Tiredness Too much alcohol Thinking distance Too many drugsPoor visibilityWet roadsIcy roadsBraking distanceTyres/brakes worn outDriving too fast
33What other measures are taken to stop motorists from speeding? Speed killsWhat other measures are taken to stop motorists from speeding?
34Thinking distanceThe distance the car travels in the split second between a hazard appearing and the driver applying the brakesReaction timerYou can test your reactions by holding the top of a 30cm ruler, hanging vertically between a partners finger and thumb.When you let go (no warning) your partner has to grip the ruler as quickly as possible.The slower your partner's reaction time the further the ruler will fall( see table, page 138, physics for you).