Orbital speed

Definition

Orbital speed is the velocity a body needs to stay in a stable orbit around another body due to gravitational forces. It depends on the masses of both objects and the distance between them.

5 Must Know Facts For Your Next Test

1. Orbital speed decreases with increasing altitude from the primary body.
2. Kepler's Third Law relates orbital period to the semi-major axis of an orbit, indirectly involving orbital speed.
3. For circular orbits, orbital speed is constant; for elliptical orbits, it varies.
4. Orbital speed at a given point can be calculated using the formula v = √(GM/r), where G is the gravitational constant, M is the mass of the primary body, and r is the distance from its center.
5. Geostationary satellites have an orbital speed that matches Earth's rotation.

Review Questions

• What happens to orbital speed as altitude increases?
• How does Kepler's Third Law relate to orbital speed?
• What is the formula for calculating orbital speed?

Related terms

Gravitational Constant:

A fundamental physical constant denoted by G used in calculating gravitational forces.

Semi-Major Axis: The longest diameter of an ellipse, important in determining orbital characteristics.

Elliptical Orbit:

An oval-shaped path followed by an object in space influenced by gravity.