Man-made Satellites

3.3

Man-made Satellites

If the linear speed of satellite, v is less than required speed, staellite will fall to a lower orbit
Satellite will revolve towards Earth until it enters atmosphere
High speed movement against air resistance will produce heat, satellite burns

Geostationary satellite	Non-geostationary satellite
Orbits the Earth
\(v=\sqrt{\dfrac{GM}{r}}\)
\(T=\sqrt{\dfrac{4\pi^2 r^3}{GM}}\)
Direction of motion same as the direction of Earth rotation	Direction of motion doesn't have to be the same as the direction of Earth rotation
T = 24 hours	T can be longer or shorter than 24 hours
Above the same geographical location	Above different geographical location
Function: communication satellite	Function: Earth imaging, GPS, weather forecast
Example: MEASAT	Example: TiungSAT, RazakSAT, Pipit, ISS

Escape velocity

The minimum velocity needed by an object on the surface of the Earth to overcome gravitational force and escape to outer space.

Earth's escape velocity: \(11\,200\,ms^{-1} /\;40\,300\,kmh^{-1}\)

Benefits and implications of Escape Velocity

Earth is able to maintain a layer of atmosphere around it
- Molecules in atmosphere has velocity (\(500\,ms^{-1}\)) lower than Earth's escape velocity
- unable to escape to outer space
Planets and jets won't escape to outer space
- both have speeds lower than Earth's escape velocity
Rockets need to be launched into outer space
- uses a lot of fuels to produce large thrust
- produce high velocity that is larger than Earth's escape velocity

3.3

Man-made Satellites

If the linear speed of satellite, v is less than required speed, staellite will fall to a lower orbit
Satellite will revolve towards Earth until it enters atmosphere
High speed movement against air resistance will produce heat, satellite burns

Geostationary satellite	Non-geostationary satellite
Orbits the Earth
\(v=\sqrt{\dfrac{GM}{r}}\)
\(T=\sqrt{\dfrac{4\pi^2 r^3}{GM}}\)
Direction of motion same as the direction of Earth rotation	Direction of motion doesn't have to be the same as the direction of Earth rotation
T = 24 hours	T can be longer or shorter than 24 hours
Above the same geographical location	Above different geographical location
Function: communication satellite	Function: Earth imaging, GPS, weather forecast
Example: MEASAT	Example: TiungSAT, RazakSAT, Pipit, ISS

Escape velocity

The minimum velocity needed by an object on the surface of the Earth to overcome gravitational force and escape to outer space.

Earth's escape velocity: \(11\,200\,ms^{-1} /\;40\,300\,kmh^{-1}\)

Benefits and implications of Escape Velocity

Earth is able to maintain a layer of atmosphere around it
- Molecules in atmosphere has velocity (\(500\,ms^{-1}\)) lower than Earth's escape velocity
- unable to escape to outer space
Planets and jets won't escape to outer space
- both have speeds lower than Earth's escape velocity
Rockets need to be launched into outer space
- uses a lot of fuels to produce large thrust
- produce high velocity that is larger than Earth's escape velocity