Gravitational Field Lines
- The direction of a gravitational field is represented by gravitational field lines
- The direction shows the direction of force
- Equivalently, they show the direction of acceleration of a test mass in the field
- The gravitational field lines around a point mass are radially inwards
- The gravitational field lines of a uniform field, where the field strength is the same at all points, is represented by equally spaced parallel lines
- For example, the fields lines on the Earth’s surface
Gravitational field lines for a point mass and a uniform gravitational field
- Radial fields are considered non-uniform fields
- The gravitational field strength g is different depending on how far you are from the centre
- Parallel field lines on the Earth’s surface are considered a uniform field
- The gravitational field strength g is the same throughout
Examiner Tip
You should be able to link gravitational field lines with vectors: the density of gravitational field lines show the magnitude of the field (i.e., the closer they are, the stronger the field), and they also indicate the field's direction.
