Energy
Energy is the ability to do work or cause change, and it exists in many forms such as kinetic, potential, thermal (heat), light, sound, electrical, chemical, and nuclear energy. One of the most important rules in science is the law of conservation of energy, which states that energy cannot be created or destroyed—it can only be transferred or transformed from one form to another. For example, a battery changes chemical energy into electrical energy, a light bulb converts electrical energy into light and heat, and plants transform sunlight into chemical energy through photosynthesis. Energy is constantly changing forms in nature and in everyday life, powering everything from moving vehicles and growing plants to weather systems and living organisms. The efficiency of these energy transformations depends on the system, and some energy is often transferred as heat. Understanding energy helps explain how the world works, making it one of the most fundamental concepts in physics and everyday life.