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Joule (J)

Quantity: energy · Category: Energy

The joule is the SI derived unit of energy, work, and heat. One joule is the energy transferred when a force of one newton displaces an object by one meter, or equivalently the power of one watt sustained for one second. It is the standard energy unit across chemistry, physics, and engineering.

Relation to SI

1 J = 1 kg·m²/s² = 1 N·m = 1 W·s

Examples

  • Raising a 1 kg mass by ~0.10 m requires about 1 J
  • Kinetic energy is computed in joules: E_k = ½mv²
  • Reaction enthalpies are reported in kJ/mol