Satellite
• The heavenly body which revolves around the planets is called satellite. e.g. Moon is satellite of earth.
• Artificial Satellites: Man-made objects revolving in certain orbits around the planet earth or other planets are known as artificial satellites.
• Geo-stationary Satellites (Parking satellites): These satellites orbit around the earth and are placed over the earth's equator, it revolves around in the same direction as that of earth and takes 24 h to complete one rotation.
• Polar Satellites: The satellites which revolve in polar orbits around the earth is known as polar satellite.
• Orbital Velocity of Satellite: It is the maximum velocity required to put the satellite into a given orbit around the earth.
\(V_o =\sqrt{\frac{gR_e^2}{R_e + h}}\)
\(= R_e\sqrt{\frac g{R_e + h}}\)
where, R = radius of earth, h = height from earth surface
and g = gravitational acceleration.
If the satellite is revolving near the earth's surface, then orbital velocity,
\(V_o =\sqrt{gR_e}\)
\(= 7.92 km/h\)
\(= 8.0km/h\)
• Revolution Period of Satellite: It is the time taken by satellite to complete one revolution around the earth.
Revolution period of satellite is given by
\(T = \frac{2\pi r}{v_o} = \frac{2\pi (R_e +h)}{v_0}\)
• Total Energy of Satellite: It is the addition of potential and kinetic energies of satellite. i.e.
\(E = - \frac 12 \frac{GMn}r\)
• Binding Energy: It is defined as the minimum energy required to be given to a satellite in order to make it escape from gravitational field of earth.
\(E = \frac{GMn}{2r}\)
where, r = orbital radius of satellite, m = mass of satellite and M = mass of earth.
