What you’ll learn4 learning objectivesChoose one objective for a focused lesson, or study the complete topic.13.2.1That, for a point outside a uniform sphere, the mass of the sphere may be• understand that, for a point outside a uniform sphere, the mass of the sphere may be considered to be a point mass at its centreSyllabus objective13.2.2Newton’s law of gravitation F = Gm1m2 / r2 for the force between two point• recall and use Newton’s law of gravitation F = Gm1m2 / r2 for the force between two point massesSyllabus objective13.2.3Circular orbits in gravitational fields by relating the gravitational force• analyse circular orbits in gravitational fields by relating the gravitational force to the centripetal acceleration it causesSyllabus objective13.2.4A satellite in a geostationary orbit remains at the same point above the• understand that a satellite in a geostationary orbit remains at the same point above the Earth’s surface, with an orbital period of 24 hours, orbiting from west to east, directly above the EquatorSyllabus objective