Gravitational field strength (A-level only) Flashcards – AQA A-level Physics (7408)

What does the arrow on a gravitational field line indicate?

The direction of the gravitational force on a mass placed there: towards the attracting mass.

How does the spacing of gravitational field lines indicate field strength?

The closer together the lines, the stronger the field.

What is the pattern of gravitational field lines around a point mass or a spherically symmetric mass?

They are radial and point towards the mass’s centre.

What is gravitational field strength $g$ at a point, in terms of gravitational force $F$ and mass $m$?

The gravitational force per unit mass: $g = \frac{F}{m}$.

What is the direction of gravitational field strength at a point?

The direction of the gravitational force on a mass at that point.

What is the unit of gravitational field strength?

$\mathrm{N\,kg^{-1}}$

What is the gravitational field strength at distance $r$ from the centre of a point mass or from the centre outside a spherically symmetric mass $M$?

$g = \frac{GM}{r^2}$, where $G$ is the gravitational constant.