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Chapter 8

Gravitational Fields

Choose the centre separation, the direction convention and the energy reference before calculating.

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  1. Mass, force and field strength

    Derive the external field, distinguish radius from altitude and assess the near-surface approximation.

  2. Potential and potential energy

    Use the zero at infinity, distinguish energy per mass from system energy and calculate signed work.

  3. Field from a potential gradient

    Read a local tangent and use its negative gradient to find the signed radial field component.

  4. Escape using an energy account

    Set the minimum escape condition and distinguish the ideal threshold from a full launch-energy calculation.

  5. Circular orbits and geostationary satellites

    Connect gravity to inward acceleration, account for final orbital energy and fit radius-period data.