Kinetic Energy Calculator

Calculate kinetic energy, mass, or velocity using KE = ½mv². Enter any two values to solve for the third. Perfect for physics students and collision analysis.

Kinetic Energy

200,000 J

Mass

1,000 kg

Velocity

20 m/s

Kinetic Energy and the Squared Speed Effect

The formula KE = ½mv² reveals why speed is so critical in collisions. Since velocity is squared, a car crash at 60 mph releases four times the energy of a crash at 30 mph, but sixteen times the energy of a crash at 15 mph. This is why speed limits near schools are low — the kinetic energy difference between 20 mph and 40 mph is fourfold, dramatically affecting injury severity.

Kinetic Energy Reference

EnergyContext
1 JA 1kg object moving at 1.4 m/s
100 JA car at 5 mph (parking speed)
1,000 JA 20g bullet at 316 m/s
50,000 JA car at 60 mph (50,000 J)
1,000,000 JA small car at 90 mph

Frequently Asked Questions

What is kinetic energy?
Kinetic energy is the energy an object possesses due to its motion. It depends on two factors: mass and velocity. Because velocity is squared in the formula (KE = ½mv²), doubling the speed quadruples the kinetic energy. This is why car crashes at higher speeds are exponentially more dangerous — a car at 60 mph has four times the kinetic energy of the same car at 30 mph.
How do I calculate kinetic energy?
Use the formula KE = ½ × m × v². For example, a 1,500 kg car traveling at 20 m/s (45 mph) has KE = 0.5 × 1,500 × 400 = 300,000 joules. This is equivalent to the energy released by 72 grams of TNT or the energy needed to lift the car 20 meters into the air.
What is the difference between kinetic and potential energy?
Kinetic energy is energy of motion — a moving car, a thrown ball, wind. Potential energy is stored energy — a ball held at height (gravitational), a compressed spring (elastic), or a charged battery (chemical). The total mechanical energy of a system is the sum of its kinetic and potential energy (conservation of energy).

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