Kinetic energy and momentum calculator
Kinetic energy and momentum of a moving mass.
Enter your values and press Calculate. Your inputs stay in the address, so you can switch language or share the link.
Formula
KE = ½ × m × v² p = m × v
How it works
Kinetic energy is the energy of motion: half the mass times the speed squared, so doubling speed quadruples the energy. Momentum is mass times velocity.
Worked example
The same calculation with the default values:
- Mass 1,200 kg
- Velocity 20 m/s
- KE = ½ × 1,200 × 20² = 240,000 J
- p = 1,200 × 20 = 24,000 kg·m/s
Result: Kinetic energy: 240,000 J · Kinetic energy (kilojoules): 240 kJ · Momentum: 24,000 kg·m/s
This is the classical (Newtonian) kinetic energy formula, accurate for everyday speeds - at speeds approaching a significant fraction of the speed of light, relativistic effects make this formula increasingly inaccurate.
Common mistakes
- Forgetting the one-half in KE = ½mv² - doubling the velocity actually quadruples the kinetic energy, not just doubles it, which this factor accounts for.
- Confusing kinetic energy (a scalar, in joules) with momentum (a vector, in kg·m/s) - they use the same inputs but describe different physical quantities and don't convert directly into one another.
- Using velocity in km/h directly in the formula - the formula requires m/s, so km/h values must be converted first (divide by 3.6).
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