Orbital speed is calculated based on the circumference of the circular orbit path that planets and moons follow around other celestial bodies. The circumference is equal to 2πr, where r is the orbital radius. The average orbital speed can be defined as V = 2πr/T, where V is the speed in meters/second, r is the average orbital radius in meters, and T is the orbital period in seconds. The orbital period is the time it takes an object to complete one full orbit, and the orbital radius is always measured from the center of the object being orbited to the orbiting object.

1. Calculating orbital speed

2. Orbital speed
~When planets move around the sun, or a moon moves
around a planet, they orbit in circular motion
- in one orbit a planet travels a distance equal to the
circumference of the circle
- this is equal to 2 pi r where r is the radius.
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3. The average orbital speed
can be defined by;
V = 2 pi r
t
Where; v = orbital speed in meters per sec
r = average radius of the orbit in meters
T= orbital period in sec

4. The orbital period or time period is
known as the time taken for an
object to complete an orbit
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The orbital radius r is always taken
from the center of the object being
orbited to the object orbit

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