L1. Energy: What Powers Everything

Energy and Its Forms

R-report

L1. Energy: What Powers Everything

Why does everything change? A falling ball speeds up, a boiling pot bubbles, and a moving car eventually stops. What drives all these changes?

Energy is the ability to make change

Energy is the ability to cause change or do work. When something happens — a rock falls, ice melts, or a light bulb glows — energy makes it possible. Energy is not a thing you can hold like a ball; it is more like the ability or power to make things happen. All of science involves energy in some form, because every change in the universe requires energy to drive it.

Energy exists in many forms

Kinetic energy is the energy of motion: a rolling skateboard, a flying bird, and a rushing river all have kinetic energy because they are moving. Potential energy is stored energy: a book on a high shelf, a stretched spring, and a fuel tank all have potential energy because they have the potential to cause change if they are released. Heat energy comes from the random movement of particles and is transferred between objects at different temperatures. Chemical energy is stored in bonds between atoms and is released when fuel burns or when organisms eat food. Light, sound, electrical energy, and nuclear energy are other important forms.

Energy can be transferred and transformed

Energy does not stay in the same form or in the same place. When you lift a book, chemical energy from your muscles is transferred to the book as potential energy. When the book falls, that potential energy is transformed into kinetic energy. When it hits the ground, some of that energy becomes sound and heat. Energy can move from one object to another through collisions, heat flow, light, or other processes. Energy can also change from one form to another: falling water releases potential energy, which becomes kinetic energy, which can be transformed into electrical energy in a hydroelectric plant.

Energy: the driver of change

Every change in the universe — from the smallest vibration of an atom to the largest motion of a planet — involves energy. Energy is not used up in the way we often think of using something; instead, it is transferred from one place to another and transformed from one form to another.

Understanding energy is the key to understanding physics. Whether you are studying motion, heat, light, electricity, or any other phenomenon, energy is the common thread that connects them all.