Question #eb544

1 Answer
Nov 2, 2016

Satellite moves faster in orbit when it is close to the planet it orbits, and slower when it is farther away.

Explanation:

The satellite experiences two forces while in orbit

  1. Force due to gravity Fg of the planet
    Fg=GMp×msR2O
    where, Mpandms are mass of the planet and mass of the satellite respectively; G is Universal gravitational constant and RO is the radius of the orbit measured from the center of the planet.
    We also know that RO=Rp+h, where Rp is the radius of planet and h is the height of the satellite above planet's surface.
  2. Net centrifugal force FC due to its circular motion
    FC=msv2RO
    where v is the velocity of the satellite.

As the satellite-planet system is in equilibrium, equating both forces we get
GMp×msR2O=msv2RO
GMpRO=v2
v21RO

From above equation it is evident that when a satellite is moved to a larger radius/higher from the planet’s surface, RO increases. To keep the system in equilibrium, the velocity must decrease.

Heights of satellites above earth and their velocities.

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