Solve mechanical energy balance, classical kinetic energy or uniform-gravity potential energy for a selected unknown. Choose units for the inputs and result; potential energy and height use a signed reference.
Formula
The following equation describes conservation of mechanical energy when net nonconservative work is zero.
- Where Ki is the initial kinetic energy
- Ui is the initial potential energy
- Kf is the final kinetic energy
- Uf is the final potential energy
This mechanical-energy equation excludes net work by friction, drag and other nonconservative forces. Total energy conservation also includes heat, work and other forms of energy. The calculator also uses KE = 0.5*m*v^2 and gravitational U = m*g*h for a positive mass in a uniform gravitational field.
Conservation of Energy Definition
Energy cannot be created or destroyed; the total energy of an isolated system is constant. A closed system can exchange energy as heat or work. Mechanical kinetic plus potential energy is conserved only when net nonconservative work is zero.
Conservation of Energy Example
How to apply conservation of energy?
- First, determine the initial potential energy.
Calculate the initial potential energy.
- Next, determine the final kinetic energy.
Calculate the final kinetic energy.
- Next, determine the final potential energy.
Calculate the final potential energy.
- Finally, calculate the initial kinetic energy.
Calculate the initial kinetic energy using the formula above.
FAQ
Total energy is conserved in an isolated system. The equation above conserves mechanical kinetic plus potential energy when net nonconservative work is zero; friction can convert mechanical energy into thermal energy without violating total energy conservation.
Kinetic energy is energy associated with motion. This calculator uses classical translational kinetic energy, KE = 0.5*m*v^2, and returns speed magnitude when solving for motion.
Potential energy depends on a system's configuration. This calculator uses gravitational U = m*g*h in uniform gravity, with signed height relative to a chosen zero-energy reference.
