What is orbital time period?

The time taken for a planet or satellite to complete one full orbit.

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How is orbital speed related to the radius of a circular orbit?

Orbital speed is inversely proportional to the square root of the radius of the orbit. This means that the larger the radius, the slower the orbital speed.

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How is the time period of orbit related to the orbital radius?

T2 ∝ r3


T = orbital time period (s)

r =  orbital radius (m)

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How is the total energy of a satellite found?

The energy of an orbiting satellite is the sum of its kinetic energy (due to its motion) and its gravitational potential energy (due to its position).

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What is the formula linking total energy (Etotal), kinetic energy (Ek), and potential energy (Ep) of an orbiting satellite?

Etotal​ = Ek​ + Ep​


Etotal = total energy of satellite (J)

Ek = kinetic energy of satellite (J)

Ep = potential energy of satellite (J)

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What is escape velocity?

Escape velocity is the velocity an object needs to escape the gravitational pull of a planet.

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What is the formula linking escape velocity (v), gravitational constant (G), mass (M), and distance (r)?

v = √r2GM​​


v = escape velocity (m s-1)

G = gravitational constant (N m2 kg-2)

M = mass (kg)

r = distance (m)

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What are synchronous orbits?

Orbital period of the satellite matches the rotation period of the body it's orbiting.

The satellite stays in the same place in the sky from the perspective of an observer on the body.

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What are the uses of satellites in low orbits?

  1. Weather monitoring
  2. Earth observation
  3. Spy satellites


They provide high-resolution, detailed data.

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What are the uses of geostationary orbits?

  1. Communication
  2. Weather monitoring 


They stay above the same point on the Earth's equator, providing constant coverage of a specific area.

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What is the relationship between orbital period and speed?

The orbital period and speed are inversely related.


This means that the higher the speed of the object, the shorter the orbital period.

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What is the formula linking gravitational potential energy (Ep), gravitational constant (G), mass of planet (M), mass of satellite (m) and the radius of orbit (r) of a satellite in a circular orbit?

Ep​ = rGMm​


Ep = gravitational potential energy (J)

G = gravitational constant (N m2 kg-2)

M = mass of planet (kg)

m = mass of satellite (kg)

r = radius of orbit (m)

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What is the period of a satellite in a geostationary orbit?

The period of a satellite in a geostationary orbit is 24 hours, which matches the Earth's rotational period.

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