Presentation on theme: "What effects how quickly a car stops?"— Presentation transcript:
1What effects how quickly a car stops? Aims:To understand that stopping distances are related to friction and speedTo understand what speed is and how it is measuredTo be able to interpret distance/time graphs
2Speed and stopping Speed tells you how far you go in a certain time The speed of a car affects how long it takes to stopThe faster you are going, the longer it takes to stopThinking time = the distance you travel whilst THINKING about stoppingBraking distance = the distance you travel once you start to BRAKE
3Stopping a car… Tiredness Too much alcohol Thinking distance Too many drugsPoor visibilityWet roadsIcy roadsBraking distanceTyres/brakes worn outDriving too fast
4Distance-time graphs 2) Horizontal line = 40 30 20 10 4) Diagonal line downwards =Distance(metres)3) Steeper diagonal line =Time/sDiagonal line =
540 30 20 10 20 40 60 80 100 Distance (metres) Time/s Distance(metres)Time/sHow far had the object gone after 20 seconds?How far had the object gone after 60 seconds?When is the object standing still?When was the object travelling the fastest?
7Activity 2How could we compare the speeds of a car on two different surfaces(The pink box on page 23 spotlight 8 may help)
8d s x t Formula triangle for measuring speed Use this equation: distancetimesxtSpeed is measured in many different units, e.g. m/s, km/h, km/s, miles per hour.The units of distance and time used will give the units to be used for speed.
10Cover the quantity you want to calculate - s (speed) ExamplesA boy travels from his home to the cinema, a distance of 10 km in 1 hour. Calculate his speed in km/h.d (distance in km)Speed in km/h =t (time in h)d10 km=1 hsxt= 10 km/hCover the quantity you want to calculate - s (speed)
11Work out the speed of the two cars which is the fastest?
12Complete the table on page 22 spotlight 8 then complete questions 1 to 5 on page 23.
13How long did the journey take? What was the total distance covered? What was the average speed for the journey? What was the average speed for the first 20 minutes and the last 20 minutes of the journey?Write a short story about this journey. What is happening in each 10 minute segment? (Finish for homework)