Gravitational Potential: Negative Values, Work and Field Strength | A-Level Physics

Why is gravitational potential below zero, and how does a scalar map predict work and field strength? This A-level Physics lesson explains the zero at infinity, V = -GM/r, potential energy and slow external work. Worked examples find Earth's surface potential, the ideal energy needed to lift a satellite, and field strength from a potential gradient. Equipotential surfaces, path independence, gradient signs and areas under field graphs connect the ideas. At 06:43, the on-screen conversion is the correct one: 70 km = 7.0 × 10^4 m. Read the lesson, practise with the topic questions, then continue to Orbits and Satellites using the links below. Supports AQA, OCR A, Pearson Edexcel and Cambridge International A-level Physics. InkPhysics is independent and is not affiliated with or endorsed by any awarding body. Chapters: 00:00 Why is gravitational potential negative? 00:20 Potential as a scalar map 00:38 Zero at infinity 00:58 Why potential is negative 01:21 The point-mass equation 01:49 Potential and inverse distance 02:13 Potential versus potential energy 02:37 Earth's surface potential 03:05 Potential differences and work 03:28 Lifting a satellite 03:57 What the energy calculation includes 04:30 Equipotential surfaces 05:21 Path independence 05:45 Field from the potential gradient 06:15 Signed component and magnitude 06:39 Worked gradient over 70 kilometres 07:16 Potential difference from graph area 07:47 Connecting the two equations 08:16 Four common misconceptions 08:36 Read the potential map https://inklearning.co.uk/physics/gra... https://inklearning.co.uk/physics/pra... https://inklearning.co.uk/physics/gra... #InkPhysics #ALevelPhysics #GravitationalPotential