1. CARS Speed and Acceleration

2. Speed To be able to: AllMostSome Define what speed is.. (MYP 2/3) Use the speed formula triangle to calculate speed (MYP 3/4) Analyse speed and time graphs (MYP 5/6) Starter – Describe how your car over comes/uses the forces acting upon it… Use your research to help you Criteria A C E

3. Put the following in order … Put the following in order … 1. of speed 2. in some creative way you choose

4. To work out the speed of an object you need to know: Distance, Time and Speed the distance travelled how long it took to travel that distance.

5. Average speed is calculated using this equation: Speed can be measured in different units, e.g. m/s, km/h, km/s, miles per hour. The units of distance and time used will determine the units to be used for speed. d s×t formula triangle Calculating Average Speed total distance total time average speed =

6. Speed formula triangle

7. 0.5 h = 10 km A girl takes 30 minutes to travel around a cross-country ski course, a distance of 10 km. Calculate her average speed in km/h. = 20 km/h Speed calculation example d (distance in km) average speed (in km/h) t (time in h) = 10 km

8. 1,800 s 10,000 m = = 5.6 m/s Sometimes the units have to be changed in a speed calculation. 30 × 60 Speed calculation example – units Calculate the average speed of the skier in m/s. d (distance in m) average speed (in m/s) t (time in s) = 10 km

9. = 3.6 km/h x 0.5 h distance (km) = speed (km/h) x time (h) A boy sets off for a walk around his village at an average speed of 3.6 km/h. How far will he travel in 30 minutes? Give your answer in km. Distance calculation = 1.8 km

10. How long would it take the boy to walk 200 m to the church, if his average speed was 1.6 m/s? Time calculation – Question 1 200 m 1.6 m/s = time = distance speed = 125 seconds

11. Car graphing activity – animation

12. Distance–time graph

13. Calculating speed from the gradient The slope of a graph is called the gradient. The gradient of the line in a distance–time graph equals the speed. It is difficult to calculate the gradient of ‘realistic’ graphs because the line is curved. Simple graphs use straight lines only, making it easy to calculate the gradient. time distance time distance

14. What is the speed of the object between points A and B? time (s) distance (m) 0213456789 0 10 20 30 40 50 60 70 A B the object has moved 60 m (70 - 10 ) it took 3 s to move this distance (6 - 3) speed = distance/time = 60/3 = 20 m/s What’s the speed?

15. 1. Time how long it takes you to run 100 m. Speed experiment – instructions total distance total time average speed = 3. Repeat the experiment for each member of your group. 2. Then calculate your average speed for the run. 4. What was the fastest average speed for your group?

16. Name distance (m) time (s) average speed (m/s) Conclusion The fastest member of the group, with an average speed of ___________, was _____________. Speed experiment – results 100 100 100 100 100

17. Speeding up vs slowing down

18. Homework What is the top speed of your car? What features does it have to enable it to have this speed? Add to your Scrap book.

19. Speed To be able to: AllMostSome Define what speed is.. (MYP 2/3) Use the speed formula triangle to calculate speed (MYP 3/4) Analyse speed and time graphs (MYP 5/6) Starter – Describe how your car over comes/uses the forces acting upon it… Use your research to help you Criteria A C E

20. Acceleration To be able to: AllMostSome Explain what acceleration is. (MYP 2/3) Use the formula triangle to solve acceleration problems. (MYP 3/4) Think about how your cars is designed to improve its acceleration. (MYP 5/6) Criteria A C E

21. The acceleration is the rate in which an object slows down or speeds up. A train accelerates in a straight line from rest. As it does, its velocity increases. The brakes on this motorcycle are causing it to slow down. This is negative acceleration or deceleration. What is acceleration?

22. The acceleration of an object can be calculated using this equation: change in speed time taken acceleration = Acceleration is measured in metres per second per second (m/s 2 ). Change in speed is measured in metres per second (m/s). Time taken is measured in seconds (s). How is acceleration calculated?

23. Using a formula triangle A formula triangle helps you to rearrange a formula. The formula triangle for acceleration (a), speed (s) and time (t) is shown below.  x Cover the quantity that you are trying to work out, which gives the rearranged formula needed for the calculation. So to find acceleration (a), cover up a… …which gives the formula… a = st

24. A racing car accelerates from rest to a speed of 60 m/s in a time of 4 seconds. What is the acceleration of the car? = 15 m/s 2 change in speed time taken acceleration = = 60 4 Acceleration problem

25. A hungry cheetah spots a gazelle and decides to chase it. The cheetah accelerates at 10 m/s 2 from rest until it reaches 20 m/s. How long did this take? acceleration = change in speed time taken = 20 10 = 2 s Acceleration problem time taken = change in speed acceleration

26. Acceleration problems calculations

27. Homework Acceleration of your car? How fast can it go 0-60? 0-100? Add to your Scrap book.

28. Acceleration To be able to: AllMostSome Explain what acceleration is. (MYP 2/3) Use the formula triangle to solve acceleration problems. (MYP 3/4) Think about how your cars is designed to improve its acceleration. (MYP 5/6) Criteria A C E

29. Reaction Times To be able to: AllMostSome Understand what reaction time is. (MYP 2/3) Explain what can affect reaction time. (MYP 3/4) Discuss the social and economical implications of speed limits. (MYP 5/6) Criteria A C E

30. Reaction Time The time it takes you to respond to a stimulus. e.g. time between seeing a red light and applying the brakes. Under test condition, reaction time is approximately 0.75 s In real conditions it’s about 1 s

31. Reaction Distance The distance the car travels in this time.

32. Stopping Distances To be able to: AllMostSome Understand what stopping and thinking distances are (MYP 2/3) Explain what can affect stopping and thinking distances (MYP 3/4) Discuss the social and economical implications of speed limits (MYP 5/6) Starter – Why do we have speeding limits Criteria A C E

33. Speed and Safety Why are speed limits important?

34. Why have speed limits? Speed limits are an important part of road safety. They aim to prevent drivers from driving at speeds that are unsuitable and unsafe. The speed limit of a particular road depends on a range of factors, such as how straight or curved it is, and its location. The faster a vehicle is driving, the longer it will take to stop – the overall distance this takes is the stopping distance. stopping distance = thinking distance + braking distance

35.   Thinking distance is the distance a car travels before the brakes are applied. Braking distance is the distance a car travels whilst the brakes are being applied. Stopping distance = thinking distance + braking distance Stopping distance Braking distance Thinking distance How long does it take a moving vehicle to stop? The stopping distance is the sum of the thinking distance and the braking distance. Stopping Distance

36. Can you match up the words with their definitions? Stopping distance Friction Thinking distance Braking distance One of the 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.

37. What factors affect braking and thinking distance? Thinking distance Braking distance Speed of car Road conditions Drugs and alcohol Tiredness Medication Condition of tyres Condition of brakes

38. Braking Car Question: A car is moving along an open road. Suddenly, a sheep walks into the road. a)What do we call the distance the car travels before the driver puts their foot on the brakes? b) Name one factor that could increase the distance the car travels in this time. c) 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 distance Medication, drugs/alcohol, speed of car, tiredness Thinking distance = Stopping distance – braking distance = 50m – 35m = 15m

39. This graphing experiment shows a movie of a car travelling along a straight road. Copy the results table shown on the next slide and complete it as the movie is playing. Record the distance the car has travelled every five seconds. Then graph your results. Note that there are teacher’s notes, in “Notes View” on this slide. Car Graphing Activity See teacher’s notes

40. Results table for Distance / Time Graph Time (s) Distance (m) 0 5 10 15 20 25 30 35 40 45 50 55

42. Results table for Distance / Time Graph Time (s) Distance (m) 0 5 10 15 20 25 30 35 40 45 50 55 0 904 76 186 234 484 634 784 994 974 16 994

45. Stopping Distances

46. To be able to: AllMostSome Understand what stopping and thinking distances are (MYP 2/3) Explain what can affect stopping and thinking distances (MYP 3/4) Discuss the social and economical implications of speed limits (MYP 5/6) Criteria A C E

47. alcohol other drugs and some medicines tiredness distractions, such as mobile phones speed What affects thinking distance? The thinking distance is the distance a vehicle travels in the time it takes for a driver to react to a situation and apply the brakes. What factors will affect thinking distance?

48. weather condition of tyres/brakes What affects braking distance? The braking distance is the distance a vehicle takes to stop once the driver has applied the brakes. What factors will affect braking distance? condition of road speed

49. Factors affecting stopping distances

50. How do speed cameras work? There are several types of speed camera., They use different methods to calculate the speed of a vehicle. Gatso speed cameras use radar to detect the speed of a vehicle, then take two photos (half a second apart) to provide visual evidence. Lines marked on the road indicate how far the vehicle has travelled in that time. Truvelo speed cameras are activated by pressure detector cables in the road. The cables are 10 cm apart and a computer calculates how long it takes the vehicle to pass from one to another, and therefore the speed of the vehicle.

51. Speeding and speed cameras

52. Stopping a car… Braking distance Too much alcohol Thinking distance Tiredness Too many drugs Wet roads Driving too fast Tyres/brakes worn out Icy roads Poor visibility

53. Stopping Distances To be able to: AllMostSome Understand what stopping and thinking distances are (MYP 2/3) Explain what can affect stopping and thinking distances (MYP 3/4) Discuss the social and economical implications of speed limits (MYP 5/6) Criteria A C E Review