P 3 Contents

1. How to Operate This PowerPoint Select slideshow and click on “From Beginning”. Click once and this box will disappear, then choose the section you wish to look at and click on next to it. P3 Contents Speed Changing Speed Forces And Motion Work And Power Energy On The Move Crumple Zones Falling Safely Energy of Games And Theme Rides

2. P3: Forces For Transport Speed Learning Objectives All: Be able to calculate speed Most: Be able to measure speed and interpret distance-time graphs Some: Be able to calculate speed from distance-time graphs Starter: Write down what you know about speed

3. What do we know? Who is faster? • Ebenezer ran 200m in 20s. In 20s Agatha ran 250m. • Ebenezer drove from Canterbury to Blue Water in 55min, Agatha did it in 49min. • Ebenezer and Agatha both fly from Heathrow to New York. Ebenezer’s flight took 6 hours 53min, Agatha’s took 7 hours 8min. • What is speed? • What do you need to measure speed? • What are the units?

4. Working it out • Follow the instructions given to you to do the experiment to measure speed Speed = Distance (m) (m/s) Time (s)

5. Speed v Velocity • Both driving at the same speed who will reach the shop first? • Scientists need to be specific so they use velocity • Velocity is both the speed and direction of travel

6. Rearranging Distance • The equation can be rearranged so that you can calculate speed, distance or time • Whichever function the variable does on one side of the equation, it will do the opposite on the other ie if it multiplies on one side it will divide on the other, if it is a plus on one side it will subtract on the other Speed = Distance (m) (m/s) Time (s) Speed Time Speed = Distance Time Speed x Time = Distance

7. Rearranging Distance • The equation can be rearranged so that you can calculate speed, distance or time • Whichever function the variable does on one side of the equation, it will do the opposite on the other ie if it multiplies on one side it will divide on the other, if it is a plus on one side it will subtract on the other Speed = Distance (m) (m/s) Time (s) Speed Time Speed = Distance Time Time = Distance Speed

8. Rearranging Distance Speed = Distance Time Speed Time Distance = Speed x Time Time = Distance Speed

9. Rearranging Distance Speed = Distance Time Speed Time Distance = Speed x Time Time = Distance Speed

10. Average Speed Speed = Distance Time Average Speed = Distance Time • Average speed is the starting speed (u) plus the final speed (v) divided by 2 • (u + v) 2 e.g. starting speed 0m/s, finishing speed 10m/s then average speed = 5m/s e.g.2 starting speed 50m/s, finishing speed 100m/s average speed = ? u = 50m/s v = 100m/s (u + v) = (50 + 100) = 150 = 75m/s 2 2 2

11. Rearranging Average Speed = Distance Time (u + v) = d 2 t Distance = Average Speed x Time d = (u + v) x t 2

12. Distance–Time Graphs – Type 1 Horizontal line = no change in distance The object is not moving, the speed is 0m/s Distance Time

13. Distance–Time Graphs – Type 2 Straight line = change in distance is constant The object is movingat a constant speed Distance Time

14. Distance–Time Graphs – Type 3 Curved line = change in distance varies The object is moving at a varying speed Speed increases here Speed decreases here Distance Time

15. Describe what this graph shows G H F D C E Distance B A Time

16. P3: Forces For Transport Changing Speed Learning Objectives All: Be able to calculate acceleration Most:Be able to interpret speed-time graphs Some:Be able to explain the relationship between acceleration and velocity Starter: On a speed-time graph what do the following represent? a) a horizontal line, b) a straight line with a positive gradient, c) a straight line with a negative gradient

17. Speed–Time Graphs – Interpreting Positive gradient = increase in speed The steeper the line the greater the acceleration A B Speed Time

18. Speed–Time Graphs – Distance The area under the line = the distance travelled Which object travelled furthest? A B Speed Time

19. Speed–Time Graphs – Interpreting Negative gradient = decrease in speed The steeper the line the greater the deceleration Speed B A Time

20. Speed–Time Graphs – Distance The area under the line = the distance travelled Which object travelled furthest? Speed B A Time

21. Speed–Time Graphs – Calculating Acceleration The gradient of the line = acceleration Speed Time

22. What is Acceleration? • What is acceleration? Write a definition in your book • What do you need to measure acceleration? • What are the units?

23. What is Acceleration? • What is acceleration? Write a definition in your book • What do you need to measure acceleration? • What are the units? Acceleration = Change in Speed (m/s) (m/s2) Time (s) m/s/s Speed Acceleration Time

24. Practical • Follow the instructions given to perform the practical then calculate the average speed, finishing speed and acceleration of an object travelling down a ramp Remember: Average speed = distance time Average speed = u + v 2 Acceleration = change in speed time

25. Acceleration Acceleration = Change in Speed (m/s) (m/s2) Time (s) • Write out the three different equations this can be rearranged into Speed Acceleration Time

26. Rearranging Acceleration = Change in Speed Time Change in Speed = Acceleration x Time Speed Time = Change in Speed Acceleration Acceleration Time

27. Acceleration and Direction • Changing the direction an object is travelling in can affect its speed and acceleration • For a car to go around a roundabout at a constant speed it needs to accelerate • Extra force is needed to make the car change direction • This extra forces is directed towards the centre of the roundabout • This makes the car turn while keeping the speed constant

28. P3: Forces For Transport Forces and Motion Learning Objectives All: Be able to explain the relationship between force, mass and acceleration Most: Be able to relate this to stopping distances Some: Be able to predict the effect of changing a factor will have on stopping distance Starter: What are the units of force, mass and acceleration?

29. Forces - What do we know? • Ebenezer and Agatha are trying roller-skating. Ebenezer is not moving but Agatha is speeding up. Are the forces acting on Ebenezer balanced or un-balanced? What about the forces acting on Agatha? • Ebenezer and Agatha are driving up the A1 to Newcastle. Ebenezer is accelerating while Agatha is driving at a constant speed. Are the forces acting on Ebenezer’s car balanced or un-balanced? What about the forces acting on Agatha’s car? • When an object is at rest or travelling at a constant speed then the forces acting on it are balanced • There are three variables that can disrupt this balance – force, mass and acceleration

30. Force, Mass and Acceleration What affect do these have on an object? • Ebenezer pushed a trolley with a 10kg bag of potatoes in it, Agatha pushed a trolley with a 5kg bag of dog food in it. They accelerated at the same rate. Who exerted the most force? • Ebenezer hit a tennis ball with 50N of force, Agatha kicked a football with the same amount of force, whose ball accelerated fastest? • Clearly there is a link between force, mass and acceleration. What do you think it is?

31. Newton’s Second Law • Isaac Newton produced 3 laws of motion • His second law of motion is F = ma Force (N) = mass (kg) x acceleration (m/s2) • This equation can be rearranged to calculate mass or acceleration • Work out what these rearranged equations would look like (try creating an equation triangle to help you)

32. Rearranging Force Force = Mass x Acceleration Acceleration Mass Mass = Force t h Acceleration Acceleration = Force Mass

33. Remember, Remember! • If an object is stationary or moving at a constant speed the forces acting on it are balanced • If an object is moving at a changing speed the forces acting on it are un-balanced • Forces always act in pairs BUT the pairs are not always balanced • F = ma

34. Stopping Distance • When you are driving a car what affects how long it takes to stop? • Massof car • Speed travelling at • Road conditions (icy, wet) • Car conditions (tyres, brakes) • Drivers reaction time – Thinking Distance } Braking Distance

35. Stopping Distance • Stopping distance is divided into 2 sections: thinking distance and braking distance • Thinking distance can be increased if the driver is: • Braking distance can be increased by the speed of the car, the road conditions or the condition of the car – these last two affect the amount of friction being applied to the car Tired Drunk On drugs Distracted or not concentrating

36. What is happening here? B A C Speed Time

37. P3: Forces For Transport Work and Power Learning Objectives All: Be able to demonstrate work done Most: Be able to calculate work done and power Some: Be able to relate power to fuel consumption Starter: Name as many different types of transport as you can

38. What is Work? • When a force moves then work is done • The force needs to move in the direction the force is operating in – lifting something is working against gravity, pushing something is not working against gravity • The amount of work done depends on the size of the force acting on the object and the distance the object is moved

39. Work done? • Ebenezer’s car breaks down so he pushes it to the side of the road. a) Is he working against gravity? b) Is he working against inertia? • Agatha goes rock climbing, is she working against gravity? • Ebenezer and Agatha have both been to the shop and have bought a 2l bottle of coke each. Agatha lives 500m from the shop while Ebenezer lives 250m from it. Who did the most work walking home? • Ebenezer and Agatha are in the gym lifting weights. Agatha lifts 10lbs and Ebenezer lifts 15lbs. Who does the most work?

40. Work and Energy • To do work you need energy – either from food (if it is a person) or from another source (if it is a machine) • Work done is a measure of the amount of energy needed to move a force • The unit of work done is Joules • Produce an equation triangle for this • Rearrange the equation to get the equations to calculate force and distance Work Done = Force x Distance moved (J) (N) (m)

41. Work, Force and Distance Work Work Done = Force x Distance Force Distance Distance = Work Done Force Force = Work Done Distance

42. Braking Distance • When a car brakes it does work • The energy for this work comes from the car’s kinetic energy when it is transformed into (mainly) heat energy by the brakes • Kinetic energy lost = work done by brakes • Knowing this you can work out the braking distance of a vehicle Braking Distance = Work Done by brakes Braking Force

43. Power • Agatha likes the Bugatti Veyron, while Ebenezer prefers the Crown Victoria – which car has the most power? • Why? • Both cars will get you from London to Edinburgh (do the same amount of work) so why is the Bugatti Veyron more powerful?

44. Power • The less time it takes for something to do work the more powerful it is • The units of power are watts (W) or kilowatts (kW) – 1000W Power = Work Done (J) (W) Time Taken (s) • Produce an equation triangle for this • Rearrange the equation to get the equations to calculate work done and time taken

45. Power, Work, and Time Work Power Time Power = Work Done Time Taken Time Taken = Work Done Power Work Done = Power x Time Taken

46. Power and Climate Change • Powerful cars have a high fuel consumption which makes them expensive to run, especially over long distances • Burning these fuels releases harmful exhaust gases plus the hazards in creating and shipping the fuels • One of the exhaust gases is CO2 which is a green house gas and contributes to climate change • The government want to reduce CO2 emissions so now the vehicle excise duty is based on the CO2 emissions

47. P3: Forces For Transport Energy on the Move Learning Objectives All: Be able to explain the relationship between kinetic energy, mass and speed Most: Be able to calculate kinetic energy Some: Be able to compare fuel types Starter: Make a list of all the different energy sources you can name that are used in vehicles

48. Kinetic Energy • Any moving object has Kinetic Energy • This energy comes from a fuel – what is the fuel for each of the following? • Which of these are renewable fuels and which are not? Car Runner Wind turbine Bicycle Aeroplane Frisbee Cheetah Kite Remote Control Car

49. Fuel Use • The amount of kinetic energy an object has depends on its size and speed • A large moving object will have more kinetic energy than a small moving object • A fast moving object will have more kinetic energy than a slowly moving object • The amount of fuel consumed will also be affected by this

50. Braking Distance • When a car speeds up, its braking distance increases but not proportionally • When the speed doubles the braking distance quadruples, and so does the amount of kinetic energy the car has