2. LEFT CLICK OR PRESS SPACE BAR TO ADVANCE, PRESS P BUTTON TO GO BACK, PRESS ESC BUTTON TO END LEFT CLICK OR PRESS SPACE BAR TO ADVANCE, PRESS P BUTTON TO GO BACK, PRESS ESC BUTTON TO END COMPUTER PRESENTATIONS FOR KS3 SCIENCE - PHYSICS ©2003, STEVE PARKER COMPUTER PRESENTATIONS FOR KS3 SCIENCE - PHYSICS ©2003, STEVE PARKER

3. 1 1 KS3 SCIENCE - PHYSICS KS3 SCIENCE - PHYSICS Forces & Movement

4. EFFECTS OF FORCES 2 2

5. 3 3 A “Force” is something which pushes or pulls an object A “Force” is something which pushes or pulls an object It can start something moving It can start something moving

6. EFFECTS OF FORCES 4 4 A “Force” is something which pushes or pulls an object A “Force” is something which pushes or pulls an object It can stop something moving It can stop something moving

7. EFFECTS OF FORCES 5 5 A “Force” is something which pushes or pulls an object A “Force” is something which pushes or pulls an object It can speed something up It can speed something up

8. EFFECTS OF FORCES 6 6 A “Force” is something which pushes or pulls an object A “Force” is something which pushes or pulls an object It can slow something down It can slow something down

9. EFFECTS OF FORCES 7 7 A “Force” is something which pushes or pulls an object A “Force” is something which pushes or pulls an object It can change the direction of something It can change the direction of something

10. BALANCED FORCES 8 8

11. 9 9 If the forces on an object are balanced, they cancel each other out and its motion stays the same If the forces on an object are balanced, they cancel each other out and its motion stays the same

12. BALANCED FORCES 10 However, if the forces on an object do not balance out, there is a “Resultant Force” on it and its motion changes However, if the forces on an object do not balance out, there is a “Resultant Force” on it and its motion changes

13. BALANCED FORCES 11 It may speed up, slow down, change direction or stop It may speed up, slow down, change direction or stop

14. BALANCED FORCES 12 If a pile of books is sitting on a table, it may seem there are no forces acting on the books If a pile of books is sitting on a table, it may seem there are no forces acting on the books

15. BALANCED FORCES 13 In fact, the weight of the books is pressing down on the table, so why don’t they fall through? In fact, the weight of the books is pressing down on the table, so why don’t they fall through?

16. BALANCED FORCES 14 The table must be pushing back against the books with an equal and opposite force, otherwise they would move The table must be pushing back against the books with an equal and opposite force, otherwise they would move

17. RESULTANT FORCE 15

18. 16 If there is a resultant force on an object, it will not just move, it will accelerate (it will move at an increasingly higher speed) If there is a resultant force on an object, it will not just move, it will accelerate (it will move at an increasingly higher speed) This is why a space craft keeps getting faster and faster as it lifts off This is why a space craft keeps getting faster and faster as it lifts off RESULTANT FORCE

19. 17 The acceleration depends on the force being applied - the stronger the force, the greater the acceleration The acceleration depends on the force being applied - the stronger the force, the greater the acceleration RESULTANT FORCE

20. 18 Acceleration also depends on how massive the object is - the bigger the mass, the slower the acceleration Acceleration also depends on how massive the object is - the bigger the mass, the slower the acceleration RESULTANT FORCE

21. FORCE= 19 There is a formula which connects force, mass and acceleration There is a formula which connects force, mass and acceleration MASSXACCELERATION RESULTANT FORCE

22. FORCE= 20 The units for this formula are The units for this formula are MASSXACCELERATION Newtons Kilograms Metres per second per second Metres per second per second RESULTANT FORCE

23. FORCE= 21 E.g. if a speed boat applies a force of 100 N to a 50 kg man, he will accelerate at 2 m per s per s E.g. if a speed boat applies a force of 100 N to a 50 kg man, he will accelerate at 2 m per s s MASSXACCELERATION RESULTANT FORCE