CAIE A Level Physics: Understanding Gravitational Fields

Gravitational Field

Force per unit mass acting on an object.

Force due to Gravity

Attractive force between all masses.

Weight

Force acting on an object due to gravity.

Gravitational Field Strength (g)

Force per unit mass at a point.

Gravitational Field Equation

g = Fg / m, where Fg is weight.

Mass (m)

Amount of matter in an object (kg).

Force (F)

Weight of an object due to gravity (N).

Gravitational Field Direction

Always towards the center of mass.

Non-repulsive Forces

Gravitational forces cannot repel objects.

Large g Value

Indicates stronger gravitational force per mass.

Weight on Jupiter

Significantly larger than weight on Earth.

Gravitational Constant (G)

Newton's constant for universal gravitation.

Radial Fields

Non-uniform fields with strength decreasing with distance.

Uniform Fields

Gravitational field strength is constant throughout.

Gravitational Field Lines

Represent direction and magnitude of gravitational fields.

Parallel Field Lines

Indicate a uniform gravitational field.

Radial Field Lines

Directed radially inwards towards a point mass.

Earth's Gravitational Field

Almost uniform near the surface of Earth.

Field Line Arrows

Indicate direction of gravitational force (attractive).

Gravitational Field Strength Decrease

Strength decreases with distance from mass center.

Calculation of Mass

m = Fg / g, using weight and g.

Examiner Tip

Distinguish between g (field strength) and G (constant).