What is the SI unit of energy?

The correct answer is Joule.

Key Points

• The SI (International System of Units) unit of energy is the Joule (symbol: J).
• One Joule is defined as the energy transferred when a force of one newton moves an object by one meter.
• The Joule is named after the physicist James Prescott Joule, who contributed significantly to the study of energy.
• 1 Joule is equivalent to 1 Newton-meter (N·m) or 1 kg·m²/s² in base SI units.
• Joule is used to measure various forms of energy, including kinetic energy, potential energy, thermal energy, and electrical energy.

Additional Information

• Watt:
  • Watt (W) is the SI unit of power, not energy.
  • 1 Watt is defined as 1 Joule per second (1 W = 1 J/s).
• Kelvin:
  • Kelvin (K) is the SI unit of temperature, not energy.
  • It is used to measure the thermodynamic temperature scale.
• Newton:
  • Newton (N) is the SI unit of force, not energy.
  • 1 Newton is the force required to accelerate a 1 kg mass by 1 meter per second squared (1 N = 1 kg·m/s²).
• Relationship Between Energy and Work:
  • Energy is the capacity to do work, and work is the transfer of energy.
  • Both energy and work are measured in Joules.
• Other Common Units of Energy:
  • Calorie (cal): Commonly used in food energy, 1 cal = 4.184 Joules.
  • Electronvolt (eV): Used in atomic and particle physics, 1 eV = 1.602 × 10⁻¹⁹ Joules.