Presentation on theme: "What keeps them in orbit?"— Presentation transcript:
1 What keeps them in orbit? SatellitesWhat keeps them in orbit?
2 SatellitesA satellite is any projectile given a large enough velocity so its path follows the curvature of the earth.
3 How fast is the earth moving? The earth moves 8000 m in the “X” direction and 4.9 m in the “Y” direction every second.Therefore, if a projectile moves equal or greater than that speed it will follow the curvature of the earth (it will never collide with earth)
4 What makes a satellite go? All objects in circular motion must have a force.The centripetal force (inward force) acting on a satellite is gravity.Gravity pulls any satellite towards the center of the earth.Gravity must equal centripetal force in order for satellites to orbitWhat happens if its less? greater?
5 Facts about satellites As the distance from earth increase:Radius increaseForce of gravity decreasesAcceleration decreasesResult = required velocity is less
6 Satellite problem constants Radius of the earth = 6.38 x 106 mMass of the earth = 5.97 x 1024 kgRemember…the radius of a satellite is the height above the surface of the earth plus the radius of the earth.
7 Satellite Practice Problems #1 Find the altitude of a satellite orbiting earth if it is moving at 6,900 m/s and the pull of gravity is 5.69 m/s2Answer: a = v2rSolve for “r”
8 Satellite Practice Problems #1 R = (6,900 m/s)25.69 m/s2R = 8.4 x 106 m x 106 mR = 2.02 x 106 m
9 Satellite Practice Problems #2 Find the velocity needed to keep a satellite orbiting if it is accelerating at a rate of 8.2 m/s2 and it is 500 km above the surface of the earth.Answer: a = v2rv2 = a x r …v = (sqrt)8.2 x mv = m/s