Orbital speed

Definition

Orbital speed is the minimum velocity an object must have to maintain a stable orbit around a celestial body. It depends on the mass of the central body and the radius of the orbit.

5 Must Know Facts For Your Next Test

1. Orbital speed is derived from balancing gravitational force and centripetal force.
2. The formula for orbital speed is $v = \sqrt{\frac{GM}{r}}$, where $G$ is the gravitational constant, $M$ is the mass of the central body, and $r$ is the radius of the orbit.
3. For a satellite orbiting Earth, low Earth orbits have higher speeds than higher orbits due to smaller radii.
4. Orbital speed decreases as altitude increases for a given central body.
5. Geostationary satellites have lower orbital speeds compared to those in low Earth orbit.

Review Questions

• What factors determine the orbital speed of a satellite?
• How does increasing the altitude of an orbit affect its orbital speed?
• Explain why geostationary satellites have different orbital speeds compared to low Earth orbit satellites.

Related terms

Gravitational Force: The attractive force between two masses, given by Newton's law of gravitation: $F = \frac{GMm}{r^2}$.

Centripetal Force: The force required to keep an object moving in a circular path at constant speed, directed towards the center of rotation.

Geostationary Orbit: An orbit around Earth with an orbital period that matches Earth's rotation period, causing satellites to appear stationary relative to Earth's surface.