Energy Calculator
Calculate kinetic, potential, elastic and thermal energy with step-by-step workings
Types of Energy
Energy is the capacity to do work. It exists in many forms and can be converted between them — but the total energy in a closed system is always conserved (First Law of Thermodynamics).
Formulas
Conservation of Energy
At the top of a roller coaster, a car has maximum potential energy and minimum kinetic energy. At the bottom, it has maximum kinetic energy and minimum potential energy. Ignoring friction, the total energy remains the same throughout: GPE + KE = constant.
// Speed Doubles → 4× Energy
Kinetic energy scales with v². Double your speed → four times the energy. This is why car crashes at 60 mph are four times more destructive than at 30 mph.
// Food Calories
Food "Calories" (with capital C) are kilocalories. 1 food Calorie = 1 kcal = 4,184 J. A 2,000 kcal diet = ~8.4 MJ of energy per day.
// kWh vs Joules
Energy bills use kilowatt-hours. 1 kWh = 3,600,000 J = 3.6 MJ. A 100W bulb running for 10 hours uses 1 kWh.
// Work at 90°
If force is perpendicular to motion (θ = 90°), no work is done. cos(90°) = 0. Carrying a box horizontally does no work against gravity.