Gravitational Potential Energy

• Gravitational potential energy


  The energy stored in an object due to its position above the earth's surface, due to the force of gravity acting on the object
• Gaining gravitational potential energy


  1. Using chemical energy stored in muscles to lift an object off the ground

  2. Storing gravitational potential energy in the object
• Losing gravitational potential energy

  1. Allowing the object to fall back to the ground

  2. Changing the stored gravitational potential energy to other forms of energy such as thermal energy and kinetic energy
• Equation for gravitational potential energy


  Gravitational potential energy (in joules) = mass (in kilograms) x gravitational field strength (in newtons per kilogram) x height (in meters)
• The equation for gravitational potential energy is not given in the exam, students must remember it
• Sample question


  • A crane lifts a 75 kilogram mass a height of 8 meters
  • The gravitational field strength is 9.8 newtons per kilogram
• Calculating gravitational potential energy in sample question


  1. Mass = 75 kg

  2. Gravitational field strength = 9.8 N/kg

  3. Height = 8 m

  4. Gravitational potential energy = 5880 J
• Practice question


  • A ball with a mass of 500 grams is lifted onto a shelf 1.5 meters above the ground
• Calculating gravitational potential energy in practice question


  1. Mass = 0.5 kg

  2. Gravitational field strength = 9.8 N/kg

  3. Height = 1.5 m

  4. Gravitational potential energy = 7.35 J
• More questions on gravitational potential energy can be found in the revision workbook