By Zencalcy Editorial TeamLast reviewed About us
Mechanical energy is the sum of an object's kinetic energy and its gravitational potential energy. In the absence of friction and air resistance it stays constant: as an object falls, potential energy converts to kinetic, and as it rises the reverse happens.
Total kinetic plus potential energy of an object.
E = ½ m v² + m g h
E is total mechanical energy in joules, m is mass, v is speed, g is standard gravity and h is height above the chosen reference. The split between kinetic and potential changes as the object moves, but the total is conserved in the absence of non-conservative forces.
| Symbol | Meaning |
|---|---|
| E | Total mechanical energy, in joules. |
| m | Mass, in kilograms. |
| v | Speed, in metres per second. |
| h | Height above the reference level, in metres. |
Kinetic energy is ½ × 2 × 3² = 9 J and potential energy is 2 × 9.80665 × 5 = 98.07 J, so the total is 107.07 J. If all of it became kinetic, the speed would be √(2 × 107.07 / 2) = 10.35 m/s.
Continue with the Potential Energy Calculator, Power Calculator, or the Braking Distance Calculator — or browse more work, energy and power tools and all physics calculators.
Only when gravity and ideal springs are the only forces doing work. Friction and air resistance convert mechanical energy into heat, so the total falls.
Results are computed from the standard equations of classical mechanics. Unit conversions use the SI definitions published by NIST. Air resistance is ignored unless the calculator names a drag model.
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Last reviewed: September 2026. See how we build and check every tool on the about page.
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Content updated: September 2026