Some communications satellites appear to stay in the same place above Earth's equator. Explain why these satellites don't fall back to Earth.
I want to know how to write a concise answer in 3 to 4 sentences to answer a test question.
All satellites stay in orbit because their momentum (mass * velocity) is in balance with the pull of gravity downward. Geostationary satellites are rotating around the earth at the same rate that the earth is rotating on its axis so they seem to stay in the same place in the sky.