Pick a real satellite, see what it actually is and where it orbits, then work out gravity, weight, orbital speed and energy yourself — using nothing but Newton's Law of Gravitation and Earth's known mass and radius.
Step 1 — Choose a satellite
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Mass of Earth (M)--kg
Radius of Earth (R)--km
Orbital altitude (h)--km
Satellite mass (m)--kg
Orbit Animation
Step 2 — Work it out
Distance from Earth's center is r = R + h, not h alone — that's the single most common source of error below. Enter your answers, then check each one.
Step 3 — All actual values
Notice: Total Energy = KE + PE always works out to −KE (equivalently, PE ⁄ 2) for a stable circular orbit. This is the orbital virial theorem — it's why total mechanical energy of any bound orbit is always negative, and why a satellite can never drift away on its own: it doesn't have enough energy to reach r = ∞.