How do satellites orbit the earth?

Hind Saed Al-Awadi|1103|Physics

What are satellites?

A satellite is any object that is orbiting the earth, sun or other massive body. Satellites can be categorized as natural satellites or man-made satellites.

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Newton’s Canon• Suppose we fire a cannon ballhorizontally from a high mountain• The projectile will eventually fall into earth because of gravity• If the cannon fired a cannon ball at a specific velocity (according to earth) the projectile will travel completely around the earth in a circular motion• If the cannon is fired in a larger velocity than the specific one it will follow an elliptical path

What launch speed does a satellite need in order to orbit the earth?

• For every 8000 meters along the horizon of earth that surface curves downward by approximately 5 meters

• For this reason, a projectile launched horizontally with a speed of about 8000 m/s will be capable of orbiting the

earth in a circular path. Assuming that it is launched above the surface of the earth and barely encounters air resistance

Launch speed less than 8000 m/s

Launch speed equal to 8000 m/s

Launch speed greater than 8000 m/s

Projectile falls to earth Projectile orbits earth in a circular path

Projectile orbits earth in a elliptical path

A satellite is a projectile

• A satellite is an object upon which the only force is gravity. Once launched into orbit, the only force governing the motion of a satellite is the force of gravity.• Therefore orbiting objects (in this case satellites) are in free fall

How does it work?• As the projectile travels tangentially a distance of 8000 meters in 1

second, it will drop 5 meters towards the earth.• the projectile will remain the same distance above the earth due to

the fact that the earth curves at the same rate that the projectile falls. If shot with a speed greater than 8000 m/s, it would orbit the earth in an elliptical path. • Gravitational force between the earth and satellite which is the

centripetal force holds satellites in orbit• The same force that pulls an apple down to the ground allows

satellites to orbit earth