Important Units and Conversion Factors:

• Joule (J): The SI unit of energy, defined as the energy transferred when applying a force of one newton through a distance of one meter.
• Kilojoule (kJ): 1 kJ = 1,000 J.
• Megajoule (MJ): 1 MJ = 1,000,000 J.
• Gigajoule (GJ): 1 GJ = 1,000,000,000 J.
• Electronvolt (eV): Energy gained by an electron when it moves through an electric potential difference of one volt. 1 eV ≈ 1.602176634×10⁻¹⁹ J.
• Kilowatt-hour (kWh): Commonly used to measure electrical energy. 1 kWh = 3.6×10⁶ J.
• Calorie (cal): Energy needed to raise the temperature of 1 gram of water by 1°C at a pressure of 1 atmosphere. 1 cal = 4.184 J.
• Kilocalorie (kcal): Often used in nutrition. 1 kcal = 1,000 cal = 4,184 J.
• British Thermal Unit (BTU): Energy needed to heat one pound of water by 1°F. 1 BTU ≈ 1,055.05585 J.
• Therm: Used to measure natural gas. 1 therm = 105,505,585.257 J.
• Foot-pound (ft·lb): Energy transferred by applying a force of one pound-force through a displacement of one foot. 1 ft·lb ≈ 1.3558179483314004 J.
• Horsepower-hour (hp·h): 1 hp·h = 2,684,519.538 J.
• Erg: CGS unit of energy. 1 erg = 1×10⁻⁷ J.
• Ton of TNT: Energy released by a ton of TNT exploding. 1 ton TNT = 4,184,000,000 J.
• Planck Energy: Energy scale at which quantum effects of gravity become significant. Approximately 1.956×10⁹ J.