• 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: $$11\,200\,ms^{-1} /\;40\,300\,kmh^{-1}$$

 Escape velocity formula $$v=\sqrt{\dfrac{2GM}{r}}$$

Benefits and implications of Escape Velocity

1. 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
2. Planets and jets won't escape to outer space
• both have speeds lower than Earth's escape velocity
3. 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