1. Gravity and the solar system LO: To define gravity and explain how satellites stay in orbit 1.The sun is the centre of what system? _____________ 2. Name the largest member of our Solar System. ____________ 3.Our solar system is in what Galaxy? ____________ 4. What is the main difference between a planet and a star? What is a satellite? 5. The Earth spins on its _____________. 6. The Earth revolves or travels around the ___________. 7. It takes the Earth _______ hours to spin on e complete time around 8. Explain why we have day and night. 9. Can you name the order of the planets closest to the sun outward?

2. In pairs, discuss what these words mean force gravity mass weight

3. Force a push or a pull Gravity an attractive force between objects with mass Weight the force of gravity acting on a body (measured in Newtons) Mass the amount of material (atoms) in an object (measured in grams, kilograms etc.)

4. Gravity Gravity depends on 2 things: If you double the distance the gravitational force divides by 4… F F/4 1) The mass of the objects 2) The distance between them F 2F If you double the mass of one object you double the force

5. 9J Let’s stay together Why do planets orbit the Sun? It ’ s the result of gravity. What will happen if you switch the gravity off?

6. Satellites Satellites orbit planets- moon and artificial satellites To stay in orbit 2 forces must be balanced Unbalanced forces =Too fast, fly off Too slow, Pulled towards the object

7. Satellites

8. N S N S N S Polar Low Earth Geo stationary- orbits at same speed as the Earth

9. Space Junk

10. 1. Draw the earth with a person on north and south poles 2. Why does the person on the south pole not fall of the Earth? 3. Which direction does the force of gravity pull you? Show this on the diagram. 4.What happens to the gravitational force between two masses if they move further apart? 5. What is weight? 6. What is the difference between weight and mass? 7. Does the force of gravity always stay the same? If not why not? 8. What happens to your weight on the moon? 9. What 2 forces allow satellites to stay in orbit? 10. If a satellite is in a low orbit, it will experience a greater force of gravity compared to a satellite in an higher orbit. What must happen to the centrifugal force (speed) for this satellite to stay in orbit?

11. launch pad on Earth low Earth orbit in space between Earth and Moon on surface of Moon Distances not to scale 9J The NASA diet? An astronaut’s weight changes on a journey to the Moon. TASK: Match these weights to the astronaut’s position. 0 N730 N750 N125 N What happens at C? 750 N 730 N 0 N 125 N Why is C nearer the Moon than the Earth? Plenary

12. Task 1 What happens to the gravitational force between two masses if they move further apart? What is weight? What is the difference between weight and mass? Does the force of gravity always stay the same? If not why not? What happens to your weight on the moon? Bonus Questions: What happens to your weight in space? Why do you think this happens?

13. Armageddon a. What is gravity? b. Why is there less gravity on the asteroid than on the earth? c. How does the reduced gravity help the vehicle jump the ravine? http://www.flickclip.com/flicks/armageddon5. html

14. Apollo 13 http://www.flickclip.com/flicks/apollo1302.htm a. What are the properties of the gravitational force? b. How does the strength of the gravitational force compare to the other forces in nature (i.e., electromagnetic, strong, and weak)? c. Does the gravitational force depend on mass? Distance? d. Why are astronauts weightless in orbit about the earth? Are they massless? e. Explain why astronauts are able to carry heavy loads in space that they would not otherwise be able to carry on earth. f. When astronauts make repairs (involving torque) on equipment in space, it is quite difficult. Explain why