U3AOS2 Topic 1: Gravitational Fields

Gravitational field strength is calculated by dividing the mass of the attracting object by the radius from the centre of the object squared.


g=GMr2g=G\frac{M}{r^2} where G=6.67×10−11G = 6.67\times 10^{-11}



A curveball often seen is to include the altitude. Make sure to account and look out for this.

r−rplanetr-r_{planet}


There is one graph that is used and it is the Field vs Distance graph.

To find the GPE the formula is to multiply the area under the graph by the mass.

ΔGPE=(areaundergraph)×mass\Delta GPE = (area under graph)\times mass

Since the y axis is the field strength which is g, and the x-axis is the distance which is h. The formula is basically GPE = mgh but with a graph.