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Gravity Challenge #2 — Circular Orbits

The orbital speed
of a satellite.

Gravity Medium

Problem

A satellite moves in a circular orbit of radius \( r = 1.6 \times 10^7\ \mathrm{m} \) around Earth. Taking \( GM = 4.0 \times 10^{14}\ \mathrm{m^3/s^2} \), calculate the satellite’s orbital speed.

  • Orbit radius\( r = 1.6 \times 10^7\ \mathrm{m} \)
  • Earth’s GM\( GM = 4.0 \times 10^{14}\ \mathrm{m^3/s^2} \)
  • Answer inm/s
The orbit is circular — gravity supplies exactly the centripetal force.
Hint: set gravity equal to the centripetal requirement: \( \tfrac{GMm}{r^2} = \tfrac{mv^2}{r} \). The satellite’s own mass cancels — solve for \( v \).
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