Synchronous (geostationary) satellite speed check: A satellite in a synchronous (geostationary) orbit moves at an altitude of about 36,000 km above Earth’s surface. What is its approximate orbital speed in km/h?

Introduction / Context:
A geostationary satellite completes one revolution in 24 hours and appears fixed over the equator. Estimating its orbital speed reinforces the link between orbital radius, period, and tangential speed for circular motion in orbital mechanics.

Given Data / Assumptions:

• Altitude ≈ 36,000 km above Earth.
• Orbital period ≈ 24 hours.
• Earth radius ≈ 6,371 km (used for context; standard speed memory aid: ~3.07 km/s).

Concept / Approach:
For circular orbits, v = 2 * π * r / T. For GEO, v is widely known to be roughly 3.07 km/s. Converting to km/h multiplies by 3600 s/h.

Step-by-Step Solution:

Verification / Alternative check:
Using r ≈ 42,164 km from Earth’s center (≈ 6,371 + 35,786) and T = 24 h yields a compatible speed near 11,000 km/h.

Why Other Options Are Wrong:

• 7,000 to 10,000 km/h: underestimate GEO speed.

Common Pitfalls:
Confusing altitude (above surface) with orbital radius (from Earth’s center) or mixing km/s and km/h.

Final Answer:
11,000 km per hour