Gravitational potential energy

Section 1: Understanding Gravitational Potential Energy

• Grasp that gravitational potential energy is the energy stored in an object due to its height above the ground. The higher the object, the greater its potential energy.
• Recognise the formula gravitational potential energy = mass x gravitational field strength x height (E_p = m x g x h), where the object’s mass is m, gravitational field strength is g, and height above the ground is h.
• Understand that the gravitational field strength (g) on Earth is approximately 9.8 N/kg.
• Remember the unit for potential energy is the joule (J).

Section 2: Energy Conservation and Gravitational Potential Energy

• Realise that according to the principle of conservation of energy, the total amount of energy in a closed system will remain constant. Energy can be transformed from one type to another, but it cannot be created or destroyed.
• Appreciate that when an object is dropped, its gravitational potential energy is converted into kinetic energy.
• Understand in the absence of air resistance, the loss of gravitational potential energy of a falling object equals the gain in its kinetic energy.

Section 3: Contextualising Gravitational Potential Energy

• Apply the concept of gravitational potential energy to real-world examples such as a roller coaster. At the top of a slope, the cars have high potential energy, which is converted into kinetic energy as the cars move down the slope.
• Be aware that gravitational potential energy depends on the reference point chosen for h=0. Although this choice is arbitrary, be consistent once it’s made within a problem.

Section 4: Addressing Common Misconceptions

• Be aware of the misconception that objects with more mass have more gravitational potential energy. While it’s true that, all else being equal, a heavier object has more gravitational potential energy than a lighter one, remember that height is also a factor.
• Work through problems where two objects of the same mass are at different heights or two objects at the same height have different masses to reinforce the correct understanding.

Understanding gravitational potential energy also requires a solid understanding of related concepts, especially energy conservation and kinetic energy. Make sure to thoroughly review these key principles and practice applying them to solve problems involving gravitational potential energy.