5.4 - Gravitational Fields

• 2 features of geostationary orbit

  Period is 24 hour Equatorial orbit
• Escape velocity

  The velocity an object needs to escape from its planets surface ( and escape its field)
• GPE

  Energy stored in an object due to its position in a gravitational field
• Gravitational field

  A region where a mass will experience a force
• Gravitational field strength

  The force exerted on a unit mass by a gravitational field
• Gravitational potential

  Is equal to the work done moving a unit mass from infinity to that point
• Gravitational potential

  Is equal to the work done moving a unit mass from infinity to that point
• Radial fields

  A field where field lines converge to a single point mass

  Shaped like a circle
• Test mass

  A mass (1kg) used to find the field strength of gravity
• Newton's law of gravitation

  Force is proportional to the product of both masses and inversely proportional to the separation squared
• Kepler's 1st law

  Planets move in an ellipse with the sun at one focus
• Kepler's 2nd law

  Area swept out by the radius to the planet in unit time is constant. This is because the speed of the planet is not constant. Planets move faster when closer to the
• Kepler's 3rd law

  Time period squared is proportional to the cube of the average distance from the sun (radius)
• Satellite

  They are objects that orbit other larger objects

  Eg natural satellites like the moon and artificial satellites