Energy Calculator

Energy is the capacity to do work or cause change. It exists in many forms: kinetic (motion), potential (position), thermal (heat), chemical, electrical, and nuclear. Energy is measured in joules (J) in SI units. A fundamental principle is that energy cannot be created or destroyed—only converted from one form to another (conservation of energy).

Kinetic energy is calculated using KE = ½mv², where m is mass in kilograms and v is velocity in meters per second. The result is in joules. Example: A 2 kg ball moving at 10 m/s has KE = ½ × 2 × 10² = 100 joules. Kinetic energy increases with the square of velocity—doubling speed quadruples the energy.

Gravitational potential energy is calculated using PE = mgh, where m is mass in kg, g is gravitational acceleration (9.81 m/s² on Earth), and h is height in meters. Example: A 5 kg object at 10 m height has PE = 5 × 9.81 × 10 = 490.5 joules. This energy converts to kinetic energy when the object falls.

Work (W) is energy transfer when a force moves an object: W = F × d × cos(θ), where F is force in newtons, d is distance in meters, and θ is the angle between force and motion. Work and energy have the same units (joules). When you do 100 J of work on an object, you transfer 100 J of energy to it.

Common energy conversions: 1 kilojoule (kJ) = 1,000 joules. 1 calorie (cal) = 4.184 joules. 1 food Calorie (kcal) = 4,184 joules. 1 kilowatt-hour (kWh) = 3,600,000 joules. 1 electron volt (eV) = 1.602 × 10⁻¹⁹ joules. For electricity bills, kWh is standard—1 kWh can power a 100W bulb for 10 hours.