How it’s calculated
Kinetic energy is the energy of motion; gravitational potential energy is energy stored by height in a uniform gravitational field, measured from a reference level you choose.
Example: a 2 kg ball moving at 3 m/s has KE = ½ × 2 × 3² = 9 J. Held 10 m above the ground it also has PE = 2 × 9.80665 × 10 = 196.1 J.
Kinetic energy grows with the square of speed, so doubling speed quadruples it.
Frequently asked questions
Why does kinetic energy depend on v squared?
Work done to accelerate a mass is force × distance, and the distance needed grows with speed, giving ½mv². Doubling speed quadruples kinetic energy and stopping distance.
Can potential energy be negative?
Yes. It is measured from a chosen zero, so a point below the reference level has negative PE. Only changes in PE matter physically.
How fast will a dropped object hit the ground?
Without air resistance PE converts to KE: v = √(2gh). From 10 m that is √(2 × 9.81 × 10) ≈ 14 m/s.
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Sources
- University Physics Volume 1, §7.2 Kinetic Energy — OpenStax
- University Physics Volume 1, §8.1 Potential Energy of a System — OpenStax
- CODATA value: standard acceleration of gravity — NIST
Formulas are taken from the free public references above. Results are provided “as is” for informational and educational purposes only. See our disclaimer.
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