How this calculation works
The Kinetic Energy & Momentum Calculator determines the mechanical energy possessed by an object in motion in Joules, kilojoules (kJ), megajoules (MJ), and foot-pounds (ft-lbs), alongside linear momentum (p = m·v).
Mathematical formula and logic
Kinetic Energy (KE) = 0.5 × Mass (kg) × Velocity² (m/s). Linear Momentum (p) = Mass × Velocity.
Worked example
A 1,500 kg automobile traveling at 25 m/s (90 km/h) possesses 0.5 × 1,500 × 25² = 468,750 Joules (468.75 kJ / 345,728 ft-lbs) of kinetic energy and 37,500 kg·m/s momentum.
Calculation assumptions
- Classical Newtonian mechanics (velocities significantly below the speed of light c).
- Rigid body motion without rotational energy components.
Frequently asked questions
What is Kinetic Energy?
Kinetic energy is the work required to accelerate a body of a given mass from rest to its stated velocity. Once acquired, the body maintains this kinetic energy unless its speed changes.
Why does doubling speed quadruple kinetic energy?
Because velocity is squared in the formula (KE = 0.5 × m × v²), doubling your speed increases your kinetic energy (and required vehicle braking distance) by 2² = 4 times.
What is the unit of kinetic energy in the SI system?
The SI unit of kinetic energy is the Joule (J), defined as 1 kg·m²/s² (or 1 Newton-meter of work).
How do I convert km/h to m/s?
Divide the speed in km/h by 3.6 (e.g. 100 km/h / 3.6 = 27.78 m/s).
What is the difference between kinetic energy and momentum?
Momentum (p = m·v) is a vector quantity that is conserved in all collisions. Kinetic energy (KE = 0.5·m·v²) is a scalar energy quantity that can transform into heat, sound, or structural deformation during inelastic collisions.