So what launch speed does a satellite need in order to orbit the earth? ... The motion of satellites, like any projectile, is governed by Newton's laws of motion.

1. How do satellites orbit the
earth?
Hind Saed Al-Awadi|1103|Physics

2. 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-

3. https://vimeo.com/9887612

4. Newton’s Canon
• Suppose we fire a cannon ball
horizontally 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

6. 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

7. 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

8. 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

9. 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