Satellites

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Satellites - PowerPoint PPT Presentation

Satellites. What keeps them in orbit?. Satellites. A satellite is any projectile given a large enough velocity so its path follows the curvature of the earth. 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.

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Satellites

What keeps them in orbit?

Satellites
• A satellite is any projectile given a large enough velocity so its path follows the curvature of the earth.
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)
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 orbit
• What happens if its less? greater?
• As the distance from earth increase:
• Force of gravity decreases
• Acceleration decreases
• Result = required velocity is less
Satellite problem constants
• Radius of the earth = 6.38 x 106 m
• Mass of the earth = 5.97 x 1024 kg
• Remember…the radius of a satellite is the height above the surface of the earth plus the radius of the earth.
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/s2
• Answer: a = v2

r

• Solve for “r”
Satellite Practice Problems #1
• R = (6,900 m/s)2

5.69 m/s2

• R = 8.4 x 106 m - 6.38 x 106 m
• R = 2.02 x 106 m
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 = v2

r

• v2 = a x r …v = (sqrt)8.2 x 6370000.5m
• v = 7227.3 m/s