Learn it
Energy is the ability to do work or cause change. It is measured in joules (J). Energy comes in many forms: kinetic (motion), potential (stored), thermal (heat), chemical (in food and fuel), electrical, light (radiant), sound and nuclear.
The law of conservation of energy says energy cannot be created or destroyed, only transformed from one form to another. A flashlight turns chemical energy (battery) into electrical energy, then light and some thermal energy.
🔎 Amazing facts
- Food labels list energy in Calories; 1 food Calorie is about 4,184 joules.
- Plants store the Sun’s energy as chemical energy in sugar.
🧪 Try it: Energy chain hunt
- Pick 5 devices at home: a toaster, a lamp, a phone, a fan, a bike.
- For each, write the input energy and the useful output energy.
- Write any ‘wasted’ energy (often heat or sound).
- Draw one as an energy chain with arrows.
Think about it: Why do devices often get warm when you use them?