1.1.4 Gravitational Potential Energy

• Gravitational potential energy (GPE)

  Energy stored in an object due to its position in a gravitational field
• Gravitational potential energy definition

  Energy an object possesses because of its height above the ground in a gravitational field
• Formula for gravitational potential energy


  E_p = mgh
• Variables in the formula for gravitational potential energy


  • E_p
  • m
  • g
  • h
• E_p

  Gravitational potential energy (measured in joules, J)
• m

  Mass of the object (measured in kilograms, kg)
• g

  Gravitational field strength (approximately 9.8 m/s² on Earth)
• h

  Height of the object above the reference point (measured in meters, m)
• Dependence of GPE

  • Greater mass increases GPE
  • GPE is directly proportional to gravitational field strength
  • Higher height increases GPE
• Gravitational potential energy is measured in joules (J)
• Examples of gravitational potential energy


  • A book on a shelf
  • A roller coaster at the top of a hill
  • A skydiver before jumping
• A book on a high shelf

  Has more gravitational potential energy than a book on a lower shelf
• At the top of a hill

  A roller coaster has maximum gravitational potential energy
• A skydiver before jumping

  Has a large amount of gravitational potential energy
• When an object falls

  Its gravitational potential energy decreases as it is converted into kinetic energy
• In a pendulum


  GPE is highest at the top of the swing and lowest at the bottom
• Energy cannot be created or destroyed, only transferred from one form to another
• When an object falls

  Its GPE is converted into kinetic energy
• Worked example calculation

  1. E_p = 5 kg × 9.8 m/s² × 10 m

  2. E_p = 490 J
• The gravitational potential energy of the object is 490 joules
• Understanding gravitational potential energy is essential for analyzing energy transformations