Gravitational Equipotential Surfaces (DP IB Physics)

Gravitational Equipotential Surfaces

• Equipotential lines (when working in 2D) and surfaces (when working in 3D) join together points that have the same gravitational potential

• These are always:

  • Perpendicular to the gravitational field lines in both radial and uniform fields

  • Represented by dotted lines (unlike field lines, which are solid lines with arrows)

• In a radial field (e.g. a planet), the equipotential lines:

  • Are concentric circles around the planet

  • Become further apart further away from the planet

  • Remember: radial field is made up of lines which follow the radius of a circle

• In a uniform field (e.g. near the Earth's surface), the equipotential lines are:

  • Horizontal straight lines

  • Parallel

  • Equally spaced

  • Remember: uniform field is made up of lines which are a uniform distance apart

• Potential gradient is defined by the equipotential lines

• No work is done when moving along an equipotential line or surface, only between equipotential lines or surfaces

  • This means that an object travelling along an equipotential doesn't lose or gain energy and ΔV = 0

Gravitational equipotential lines in a non-uniform and uniform gravitational field