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Rockets and Satellites

Rockets and Satellites. Key Concepts How does a rocket lift off the ground? What keeps a satellite in orbit? Key Terms Satellite Centripetal force. How do rockets lift off?. Rockets lift off because of Newton’s third Law They burn fuel and push exhaust gases downward at a high velocity

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Rockets and Satellites

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  1. Rockets and Satellites Key Concepts How does a rocket lift off the ground? What keeps a satellite in orbit? Key Terms Satellite Centripetal force

  2. How do rockets lift off? • Rockets lift off because of Newton’s third Law • They burn fuel and push exhaust gases downward at a high velocity • The gases push upward on the rocket with an equal but opposite force • This upward pushing force is called thrust • Thrust must be greater than gravity for the rocket to rise and accelerate into space

  3. What is a satellite? • Any object that orbits another object in space • Our moon is a natural satellite • Artificial satellites are launched into orbit • Used for communications, military intelligence, weather analysis and geographical surveys • The ISS (International Space Station) is an example of an artificial satellite

  4. Circular Motion • Artificial satellites travel around Earth in almost circular path • An object moving in a circular path is accelerating because it is constantly changing direction • If an object is accelerating, a force must be acting on it – called centripetal force • Centripetal means center seeking • The Earth’s gravity is the centripetal force for the satellite. It keeps pulling the satellite towards the Earth

  5. Satellite Motion Q: Why don’t satellites fall to Earth like a thrown ball does? A: They have a greater horizontal velocity than a ball thrown on Earth

  6. Explanation: • A ball thrown has horizontal force moving it forward. Gravity is a force acting to pull it to the ground. The more force you give the ball the faster it travels horizontally and the greater distance it travels before hitting the Earth • A satellite in orbit around the Earth is continuously falling towards the Earth, but because the Earth is curved and they are traveling so fast , they don’t hit but travel around it • A satellite is a falling projectile that keeps missing the ground!!

  7. Satellite Motion • A satellite does not need fuel because it continues to move ahead due to its inertia • Gravity continuously changes its direction • The speed required to keep a satellite in orbit is 7,900m/s

  8. Satellite Location • Mapping and observation satellites are put into low orbits of less than 1,000 km • Completes an orbit in less than 2 hours • Satellites such as communications satellites put into higher orbits (36,000 km) where they circle the Earth in 24 hours Because of this they remain over the same point on Earth – • Geosynchronous orbit

  9. Sources • http://library.thinkquest.org/C0110484/content.php?id=62 • http://www.splung.com/content/sid/2/page/satellites • http://commons.wikimedia.org/wiki/File:Centripetal_force.PNG • http://www.stockcarscience.com/scienceTopics/scsRacing_CentrifugalForce.php • http://www.spacetoday.org/Satellites/YugoWarSats.html • http://www.nasa.gov/mission_pages/station/multimedia/sts114_7200.html • http://exploration.grc.nasa.gov/education/rocket/rktth1.html

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