Orbital Velocity

Definition

Orbital velocity is the speed at which an object, such as a satellite or planet, moves in its orbit around another object. It is a crucial parameter that determines the stability and characteristics of an object's orbital path.

5 Must Know Facts For Your Next Test

1. Orbital velocity is inversely proportional to the radius of the orbit, as described by Kepler's third law of planetary motion.
2. Higher orbital velocities are required for objects in lower orbits to maintain stable circular paths around a central body.
3. Satellites in geostationary orbit have an orbital velocity of approximately 3 km/s, matching the rotation of the Earth.
4. The International Space Station orbits the Earth at an average speed of 27,600 km/h, or 7.66 km/s.
5. Orbital velocity is a key factor in determining the energy required to launch and maintain a satellite in a specific orbit.

Review Questions

• Explain how orbital velocity is related to the stability of a satellite's orbit.
  • Orbital velocity is a critical factor in maintaining a stable satellite orbit. According to Kepler's third law, the orbital velocity of a satellite is inversely proportional to the radius of its orbit. Higher orbital velocities are required for satellites in lower orbits to generate the necessary centripetal force to counteract the gravitational pull of the central body and remain in a stable circular path. If the orbital velocity is too low, the satellite will fall back to the surface, while if it is too high, the satellite will escape the orbit.
• Describe how orbital velocity varies for different types of satellite orbits.
  • The orbital velocity of a satellite depends on its distance from the central body. Satellites in lower orbits, such as the International Space Station, have higher orbital velocities to maintain their closer proximity to the Earth. In contrast, satellites in geostationary orbit, which match the rotational speed of the Earth, have a much lower orbital velocity of around 3 km/s. The orbital velocity also varies for elliptical orbits, with the satellite moving faster at the perigee (closest point to the central body) and slower at the apogee (farthest point).
• Analyze the role of orbital velocity in the launch and maintenance of a satellite.
  • Orbital velocity is a critical factor in the launch and maintenance of a satellite. During the launch phase, the rocket must impart enough velocity to the satellite to overcome the Earth's gravity and achieve the desired orbital altitude. The specific orbital velocity required is determined by the satellite's intended orbit, with higher velocities needed for lower orbits. Once in orbit, the satellite must maintain its orbital velocity to counteract the gravitational pull and remain in a stable path. Adjustments to the satellite's orbital velocity may be necessary over time to compensate for perturbations and maintain the desired orbit.

Related terms

Centripetal Force: The force that causes an object to move in a circular path, directed towards the center of the circular motion.

Gravitational Force: The attractive force between two objects with mass, governed by Newton's law of universal gravitation.

Kepler's Laws of Planetary Motion: A set of three laws describing the motion of planets around the Sun, formulated by Johannes Kepler.