Cars

1. Cars And Forces

2. Forces Introduction What do you need in order to balance? Starter – Say what you know about forces

3. What is a force? What does it do?

4. What are forces?

5. a push a pull a turn You cannot see a force. But you can feel a force and see the effect of the force. Forces make things happen or stop them from happening. Name 5 ways in which you have used a force today. Identifying Forces - What is a force? What is a force and what does it do? A force is…

6. Label each of these as a push or a pull or both. Answering a phone Mum starting kids on a slide Using a pogo stick PULL PUSH PUSH & PULL PULL PUSH & PULL PULL Picking flowers Using a yoyo Tug- of- war

7. Forces Introduction What do you need in order to balance? Review Starter – Say what you know about forces

8. In each picture, identify the main force and describe its effect. Click on the picture to find the force

9. Reminder: Link the Labels and the Diagrams A. B. C. Push Pull Twist

10. Practical Activity Safety! Springs?

11. Investigation: Observing Forces in Action

12. Types of forces There are many different types of forces. Some act by contact and are called ‘contact forces’. e.g. hit a ball wind blowing ocean waves crashing on rocks

13. Types of forces Contact forces include: Applied the force applied to an object by a person or another object. Frictional the force exerted by a surface as an object moves across it. Tension the force which is transmitted through a string, rope, cable or wire when it is pulled at both ends.

14. Types of forces Normal the support force on an object which is in contact with another stable object. Spring the force exerted by a stretched spring on any object attach Elastic Make objects change shape e.g. spring, rubber ed to it.

15. Types of forces Elastic Make objects change shape e.g. spring, rubber

16. Types of forces Some forces do not need contact to occur, and can act at a distance. These are called ‘non-contact forces’. e.g. gravity.

17. Types of forces There are 4 non-contact forces: Gravitational Caused by Earth pulling objects down Electrical Due to charged objects

18. Types of forces Magnetic Due to magnets e.g. magnets on fridge, cupboards

19. Types of Forces Which of the following are contact/non-contact forces? Friction Buoyancy Magnetism Electrostatics Elastic Gravity • CONTACT • CONTACT • NON CONTACT • NON CONTACT • CONTACT • NON CONTACT

20. What forces are happening? Look at the following image • What examples of forces can you see? • What are the pushing and pulling forces? • What are the forces being caused by gravity? • What are the lifting forces? • What are the muscular and electrical forces?

22. Effect 1. A force can change the shape of an object. Effect 2. A force can change the speed of an object, making it faster or slower. It can keep it going at the same speed Effect 3. A force can change the direction of an object. Forces can affect things in 3 ways. Can you name them?

23. 20 seconds think time Be ready to share! 2 minutes to share with your group Starter What do forces do? In your groups of 4 think of 4 statements that can describe what forces can do to this car!!

24. What Forces are acting upon this car? Starter Hands up!!!

25. Normal Thrust Air resistance Friction Gravity/weight

26. Gravity The force of GRAVITY is what keeps us on the SURFACE of the EARTH. You do not have to be TOUCHING the Earth to feel the force of gravity. GRAVITY ON EARTH PULLS YOU DOWN. GRAVITY ALWAYS PULLS; IT NEVER PUSHES. We can draw an arrow on the shark and car to show the direction of gravity:

27. Upwards Forces I If there is a downwards force of gravity pulling on a car then why does it not get pulled into the ground? Reaction There must be a force PUSHING UP on the car that stops it getting pulled into the ground. Gravity Do you know what we call this force? The REACTION FORCE.

28. Upwards Forces II If there is the downwards force of gravity pulling down on a floating shark then why does it not sink deeper into water? Upthrust There must be a force PUSHING UP on the shark that stops it getting pulled further down. Gravity Do you know what we call this force? The UPTHRUST.

29. Force Diagrams exercise Label the forces acting on a rocket moving through the Earth’s atmosphere. Upthrust Air resistance Gravity Thrust

30. Force Diagrams Exercise Label the forces acting on the shark. Upthrust Friction Thrust Gravity

31. Forces Can…… What causes these changes???? change shape change speed change direction

32. Direction and Strength of Forces Forces can act upwards, downwards, sideways, or any direction at all. To show the direction of a force you can use an arrow. You can then show the strength of the force by the length of the arrow. A large arrow means a strong force, and a small arrow means a weak force

33. Force Diagrams Which arrow(s) could show Ellie hitting a nail? Which could show John lifting a 100N weight – and which a 200N weight? • We use arrows to show • The direction • The size • of forces A B C D The bigger the arrow, the bigger the force.

34. Balanced and Unbalanced Forces If forces balance, do they cancel each other out? Starter – Why is a motorbike faster than a bicycle?

35. Balanced Forces Two equal forces of the same magnitude acting in opposite directions. i.e there will be no motion until one force is greater than the other

36. Unbalanced Forces cause acceleration because there is an individual force which is not being balanced by a force of equal magnitude and in the opposite direction. i.e when one force is greater than another therefore there will be motion.

37. Balanced and Unbalanced Forces Reaction Consider a car standing on a road. What forces are acting on it? These two forces would be equal – we say that they are BALANCED. The car doesn’t move anywhere. Gravity/Weight

38. Balanced and Unbalanced Forces Reaction What would happen if we took the road away? Gravity/Weight

39. Balanced and Unbalanced Forces What would happen if we took the road away? The car’s weight is no longer balanced by anything, so the car falls downwards… Gravity/Weight

40. Balanced and Unbalanced Forces Imagine a car travelling at a constant speed of 50km/h. The engine provides sufficient force to just overcome all the frictional forces that are acting to decrease the speed. 500N 500N

41. Balanced and Unbalanced Forces 500N 500N 60 km/h The air resistance will decreases because the car has a “tail wind” (it is being blown from behind). This means the forces acting on the car are no longer balanced. 400N 500N >50 km/h The car will increase in speed (accelerate) until the forces are balanced again.

42. Balanced and Unbalanced Forces –summary • If the forces are unbalanced, two things can happen: • Thespeed can change.This is called acceleration. • Thedirectionof motioncan change. • If the forces on an object are balanced: • and the object isstationary,it will remain stationary • and the object ismoving, it will continuetomove at the same speed and in a straight line. • In other words, the object will continue to do what it is already doing without any change.

43. When the thrust and drag forces are balanced, the car travels at a constant speed. drag thrust What happens to the speed of the car when the thrust and drag forces are unbalanced?

44. What forces are acting on a racing car travelling at a constant speed? Drag forces oppose the thrust force and slows the car. Where are these frictional forces? A thrust force makes the car move forward. Where does this force come from? drag thrust The friction of air against the body of the car also opposes the car’s movement. This type of friction is called air resistance. The friction of the tyres on the road opposes movement of the car.

45. Forces Questions • Use the worksheet • Work through the questions by yourself • Then share your answers with someone else

46. Measuring Forces The unit used to measure force is the Newton (N), named after Sir Isaac Newton. The table below gives you some idea of the approximate sizes of some forces. That’s right, I have my own measurement

47. Measuring Forces Being able to read numbers from scales on measuring instruments is very important. How much force are these force metres measuring? (they are also called Newton metres)

48. 0 __ _ _ _ _ 5 __ _ _ _ _ 10 __ Click here for answer Click here for answer Click here for answer Reading Newton Meters What force is acting on each Newton Meter? 0 __ _ _ _ _ 10 __ _ _ _ _ 20 __ 0 __ _ _ _ _ 25 __ _ _ _ _ 50 __ 1N 12N 46N

49. Next to your Must & should objectives draw either…. A smiley face if you understand it A straight face if you partly understand it A sad face if you don’t understand it

50. Cars and Forces Review!