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About

Kinetic energy quantifies the work an object can do by virtue of its motion. In crash safety analysis and ballistics, this value is more critical than velocity alone because energy scales with the square of the speed. Doubling your speed quadruples the destructive potential.

This tool converts mixed units (like mass in pounds and speed in km/h) into the standard metric output (Joules). The specific value proposition here is the "Impact Visualizer," which contextualizes abstract Joule figures into tangible mechanical equivalents, such as dropping a heavy weight from a specific height.

physics energy joules crash safety mass velocity

Formulas

The calculation is based on classical mechanics, assuming non-relativistic speeds.

KE = 12 m v2

Where:

  • m = Mass (kg)
  • v = Velocity (m/s)
  • KE = Kinetic Energy (J or kg⋅m2/s2)

The relationship is quadratic; a car moving at 100 km/h has four times the energy of one moving at 50 km/h.

Reference Data

ObjectMass (kg)Velocity (m/s)Velocity (km/h)Kinetic Energy (J)TNT Equivalent
Baseball Pitch0.145451621470.035 g
Bullet (.45 ACP)0.0152609365070.12 g
Sprinter8010364,0000.95 g
Car (Urban)1,50013.448134,67032 g
Car (Highway)1,50029105630,750150 g
Truck (Loaded)36,000259011,250,0002.68 kg
Airplane (Landing)70,00070252171,500,00041 kg

Frequently Asked Questions

This results from the velocity term being squared (v^2) in the physics equation. While momentum (p = mv) scales linearly with speed, kinetic energy scales exponentially. This is why high-speed vehicle collisions are disproportionately more severe than low-speed bumps.
Yes. The tool automatically handles the conversion factors. Internally, 1 mph is converted to approximately 0.44704 m/s, and 1 lb is converted to 0.453592 kg before the formula is applied.
Technically, no. This tool uses Newtonian mechanics. For objects approaching the speed of light (c), relativistic formulas are required. However, for all everyday objects (cars, bullets, trains), this formula is accurate.