Definition
Satellite Motion is the orbital path of a projectile launched horizontally with sufficient speed such that its rate of fall matches the curvature of the planet.
Why It Matters
It is the basis for global telecommunications, space stations, and GPS.
Core Concepts
- Components of Projectile Motion:
- Horizontal: Constant velocity (no horizontal force).
- Vertical: Constant acceleration ().
- Meaning: Near Earth’s surface, vertical speed changes at roughly downward.
- Resulting Path: Parabola.
- Orbits:
- Circular Orbit: A satellite “falls around” Earth. The speed must be . Gravity acts perpendicular to motion, so speed remains constant.
- Elliptical Orbit: If speed , the satellite overshoots a circle. Speed varies: fastest at perigee (lowest PE, highest KE) and slowest at apogee (highest PE, lowest KE).
- How to read: “Approximately 8 kilometers per second;” “approximately 11.2 kilometers per second.”
- Meaning: Orbital speed balances gravity’s pull—too slow falls back, too fast escapes Earth’s gravity well.
- Escape Speed: The speed required to break free from a celestial body’s gravitational pull ( for Earth).
- How to read: “The escape speed is approximately 11.2 kilometers per second for Earth.”
- Meaning: Minimum launch speed to never return—total energy becomes non-negative.