1. Do now! Is there anything to complete in your books?. Can you make a note that we will be having a “ Space and Gravity ” TEST on Thursday 24 th September.

2. Satellites

3. How far could you kick a dog? From a table, medium kick.

4. How far can you kick a dog? Gravity

5. Harder kick?

6. Harder kick Gravity

7. Small cannon? Woof! (help)

8. Small cannon Gravity Woof! (help)

9. Bigger cannon?

10. Bigger cannon Gravity

11. Even bigger cannon?

12. Even bigger cannon Gravity

13. VERY big cannon?

14. VERY big cannon Gravity

15. Humungous cannon?

16. Dog in orbit! The dog is now in orbit! (assuming no air resistance of course)

17. Dog in orbit! The dog is falling towards the earth, but never gets there!

18. Dogs in orbit! The force that keeps an object moving in a circle is called the centripetal force (here provided by gravity) Gravity

19. Other examples Earth ’ s gravitational attraction on moon

20. Uniform circular motion The centripetal acceleration/force is always directed towards the centre of the circle Centripetal force/acceleration velocity

21. Note! There is no such thing as centrifugal force! (at least not until you get to university!) CENTRIFUGAL

22. Types of orbits

23. Geostationary The satellite orbits once every 24 hours, so appears to stay above the same point on the earth ’ s surface Looking from above the North pole

24. Geostationary Useful for communications satellites. Also for weather over one area.

25. Polar Satellite orbits over the poles

26. Polar Useful for mapping and remote sensing when the whole of the earth ’ s surface needs to be studied

27. Some famous satellites

28. Sputnik (4 th October 1957)

29. Russian 84 kg, 58cm diameter 800km above the earth 30 000km/h Orbited every 90 mins Fell after 92 days

30. Sputnik 2 (a month later)

31. 450 kg Carried a dog! (Laika) Laika is believed to have died from overheating in the cabin a few hours after launch It ’ s a dogs life.

32. Hubble Space telescope

33. Launched in 1990 13.1m long Doesn ’ t have to see through the earth ’ s atmosphere

34. That ’ s it!

35. Can you try some questions now? Page 141 in your book. Answer in full sentences please. TEST next Thursday 24 th September. Mr Porter is giving you a summary sheet to stick in.