FORCES AND THEIR EFFECTS

1. FORCES AND THEIR EFFECTS Unit 7K Year 7 Science

3. Index introduction lesson 1: Are some magnets stronger than others? lesson 2: What forces act on a parachute? Homework task 2 lesson 3: How much do balls bounce? lesson 4: Do rollers make it easier to drag heavy things? lesson 5: Why is iron heavier than aluminium? lesson 6: Are objects lighter under water? lesson 7: Why are some toy cars faster than others? lesson 8: Do things float better in salty water? lesson 9: Is friction sometimes useful? lesson 10: Do pulleys help with lifting?

4. Forces • What are forces? • How do we measure forces? • How do we use forces in our ordinary lives? • How do forces affect our lives?

5. What do all these terms mean? • FORCE: the influence that produces a change in a physical quantity; "force equals mass times acceleration" (Newtons) • POWER: the rate of doing work; measured in watts (joules per second) • WORK: "work equals force times distance" • ENERGY: the capacity of a physical system to do work (joules)

6. Introduction Getting help You will be loaned a study guide Use our web site This unit is all about FORCES pushes, pulls and twists Forces are measured in NEWTONS http://www.westwightmiddle.iow.sch.uk/science.htm

7. Lesson 1 Are some magnets stronger than others?

8. Learn about magnetic force Learn to list the key variables effectively Learn to evaluate the way you work Make careful measurements. Learn how to use the guide mats Make a proper variables list Record your results in a table Objectives and what I am looking for

9. A variety of different magnets 30 cm rules marked in mm Steel ball bearings Results tables Level mats Study guides (3 levels differentiated) Equipment

10. Learn to list the key variables effectively Learn to evaluate the way you work Make careful measurements. Are some magnets stronger than others? • Watch a demonstration of how to test. • What are variables? • Use whiteboards to list the variables.

11. Learn to list the key variables effectively Learn to evaluate the way you work Make careful measurements. Are some magnets stronger than others? New page. Date and title in your book. • Planning • Make a list of the key variables • Which variable will you test? • Which variable will you measure? • Which variables will you keep the same?

12. Learn to list the key variables effectively Learn to evaluate the way you work Make careful measurements. Are some magnets stronger than others? • Put the ball bearing on the table. • Move the magnet nearer to the ball bearing. • How close was the magnet when the ball started to move? Measure. • Record your results and try again with a different magnet.

13. Learn to list the key variables effectively Learn to evaluate the way you work Make careful measurements. Are some magnets stronger than others? Let’s share our results Observations State which magnet is the strongest according to your results.

14. Work in pairs Learn to list the key variables effectively Learn to evaluate the way you work Make careful measurements. Are some magnets stronger than others? Evaluation • How well did your test go? • Did you feel that your results were accurate? • How could you have improved your test in order to get more accurate results or results you could have been more sure of?

15. Lesson 2 What forces act on a parachute?

16. What forces act on a parachute? Parachute video (it might work)

17. Equipment • Digital camera • A football • Parachutes • Timers • Whiteboards, pens & erasers • Study guides (3 levels differentiated)

18. To learn about a force called DRAG To learn to draw force diagrams To learn how to mark forces on a diagram Make a diagram that clearly shows the forces that act on it. Write to describe which force is largest. Write to explain how you know. OBJECTIVES& what I am looking for

19. To learn about a force called DRAG To learn to draw force diagrams To learn how to mark forces on a diagram How to mark force arrows on diagrams. lift drag thrust New page, date & title. Copy the diagram. weight

20. To learn about a force called DRAG To learn to draw force diagrams To learn how to mark forces on a diagram Football • We will go into the playground to watch a football and bring back a photograph.

21. Football photograph • Trim and fix the photograph into your book. • Use arrows and straight lines to mark: • Gravity • Drag To learn about a force called DRAG To learn to draw force diagrams To learn how to mark forces on a diagram

22. Next bit… • DVD video input: BBC Class clips

23. Work in pairs To learn about a force called DRAG To learn to draw force diagrams To learn how to mark forces on a diagram Plenary: What forces act on a parachute? • Try a parachute in the lab from a height of exactly 2 metres. • NOW RECORD THIS ON YOUR GROUP’S WHITEBOARD • Decide what force pulls the parachute down. • Decide what force holds the parachute up. • Which of the forces was greatest? Explain how you know. HOMEWORK

24. To learn about a force called DRAG To learn to draw force diagrams To learn how to mark forces on a diagram What forces act on a parachute? IN YOUR BOOK • The force that pulls the parachute down is… • The force that holds the parachute up is. • Draw an accurate 2d diagram that shows the parachute and the two forces acting on it. • The force that was greatest was… I know this because…

25. Finishing up • Forces ‘Hammer & Feather on the Moon’. (Class Clips DVD)

26. Homework task 2 • Use your knowledge of DRAG to explain why sports cars are streamlined. HOMEWOK SHEET

27. Use your knowledge of DRAG to explain why sports cars are streamlined. Use your knowledge of DRAG to explain why sports cars are streamlined. Use your knowledge of DRAG to explain why sports cars are streamlined. Use your knowledge of DRAG to explain why sports cars are streamlined. Use your knowledge of DRAG to explain why sports cars are streamlined. Use your knowledge of DRAG to explain why sports cars are streamlined. Use your knowledge of DRAG to explain why sports cars are streamlined. Use your knowledge of DRAG to explain why sports cars are streamlined. Use your knowledge of DRAG to explain why sports cars are streamlined.

28. Lesson 3 How much do balls bounce?

29. Getting started… • Draw a ball falling. Think about its shape. • Draw a ball that has hit the ground and is about to bounce back up. Think about its shape.

30. How do forces make things bounce? Are my measurements accurate? Why is it important to repeat my tests? How can I use my scientific knowledge to explain? Be able to do a test and make accurate measurements. Be able to repeat measurements to check. Be able to clearly describe what happened. Be able to use your knowledge to explain how and why things happen. OBJECTIVES& what I am looking for

31. Which forces make balls bounce? 1st bounce 2nd bounce

32. Clamp stand with clamp and boss. Metre rule. Table tennis ball. Results table. Study guides. Equipment Equipment table tennis ball clamp stand metre rule

33. Results

34. Conclusion • According to your results, describe what happened. • Use your understanding to explain why the first bounce was more than the second bounce.

35. Something to think about… • The falling ball had kinetic energy because it was moving. • The amount of movement got less after the first bounce. • So, where did the kinetic energy go?

36. Plenary & finishing off… • Your group might be asked to read your conclusion. • Copy your conclusion to your exercise book. Improve it as you go. • Homework: Complete the conclusion in your book.

37. Forces & their effects: Lesson 4 Do rollers make it easier to drag heavy things?

38. Just for starters… • Draw a picture of a bloke dragging a heavy rock. • Draw a picture of the same bloke dragging a heavy rock using rollers. • Can you show which one is the hardest work?

39. To learn how to write why your test is fair. To learn how to make a useful bar chart. To extend your ability to explain why things happen. Know about control, independent and dependent variables. Write a useful prediction. Record your results accurately. Write to explain why things happened. Write an evaluation. OBJECTIVES & what I am looking for

40. Equipment • FOR GROUP WORK: • Dowel rollers • Force meters • String • A brick • Study guiders • Results tables • Level mats

41. Key variables INDEPENDENT VARIABLE The variable I will test is… DEPENDENT VARIABLE The variable I will measure is… CONTROL VARIABLES The variables I will keep the same are… Redraft into your exercise book.

42. Practical bit… RESULTS Use a board to protect your bench.

43. Conclusion • Produce a graph that shows these results clearly. [What should my graph look like?] • Write to explain what happened in terms of forces and energy. [What should my work look like?] • Plenary: Evaluate your test.

44. A clear graph Force (N) CONCLUSION PAGE

45. Model conclusion If the brick is dragged along the ground, the rough surfaces lock together and make lots of friction. All of the surface of the brick is touching the ground. The bigger the surface, the more friction there is. It takes a lot of force to drag the brick. If you use rollers, the rough surfaces do not lock together and so there is much less friction. So it takes much less force to pull the block. PREVIOUS PAGE

46. Forces & their effects: Lesson 5 Why is iron heavier than aluminium?

47. To learn the idea of density. To learn to measure and compare different materials. You can measure mass in grams. You can measure volume in cm³ . You can record your results in tables. You can calculate the mass of 1 cm³ of each material. OBJECTIVES& what I am looking for

48. Equipment FOR GROUP USE • Metal blocks (materials kit) Iron, brass, aluminium & lead HAZARD • Electronic scales • Study guides

49. Stage 1 • What is the mass of each metal block? (Measure in grams) • Make a table of your results.

50. Was this a fair comparison? • Describe why your test is not fair. • Can you work out what the mass would be if every block was 1 cm³? brass iron lead aluminium