Gravitational and Elastic Potential Energy
Use the near-Earth mode for modest height changes where gravity can be treated as constant. Use the two-body mode when distance between mass centres matters, and the spring mode for an ideal linear elastic spring.
Near Earth
PE = mgh measures energy relative to a chosen reference level and can solve for energy, mass, height or gravity.
Two bodies
U = −GMm/r uses the universal gravitational constant and can also calculate a change between two radii.
Elastic spring
PE = ½kx² models stored energy for a spring that follows Hooke's law.
Potential Energy FAQ
What is potential energy?
Potential energy is stored energy associated with position or configuration. Its definition depends on the physical system and a chosen reference.
Why does mgh need a reference height?
Near-Earth gravitational potential energy is a difference relative to a chosen zero level. Changing that reference changes the reported value, not the physical energy difference between two heights.
Why is universal gravitational potential energy negative?
The conventional zero is at infinite separation. Work must be supplied to separate a bound pair to infinity, so its potential energy at finite distance is negative.
What is elastic potential energy?
An ideal linear spring stores PE = ½kx², where k is spring stiffness and x is compression or extension from equilibrium.