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Energy is the currency of the physical universe—nothing happens without it. In Physical Science, you're being tested on your ability to recognize different energy forms, understand how they transform from one type to another, and apply the law of conservation of energy to real-world scenarios. These concepts connect directly to topics like motion, heat transfer, waves, chemical reactions, and electricity—essentially the backbone of your entire course.
Here's the key insight: energy is never created or destroyed, only converted. When you see a roller coaster climbing a hill, a battery powering a phone, or the sun warming your face, you're watching energy transformations in action. Don't just memorize the list of energy types—know what form the energy takes, what causes it, and how it converts to other forms. That's what separates a 3 from a 5.
These fundamental energy types describe objects based on whether they're moving or have the potential to move. Mechanical systems constantly exchange these two forms while keeping total energy constant.
Compare: Kinetic Energy vs. Potential Energy—both are forms of mechanical energy, but kinetic depends on motion while potential depends on position. If an FRQ shows a falling object, trace how PE converts to KE while total mechanical energy stays constant (ignoring friction).
These energy types are locked within substances themselves—in chemical bonds, atomic nuclei, or particle motion. Releasing this stored energy typically requires a reaction or temperature change.
Compare: Chemical Energy vs. Nuclear Energy—both are stored in matter, but chemical energy involves electron bonds while nuclear energy involves forces holding the nucleus together. Nuclear reactions release roughly a million times more energy per unit mass—that's why a small amount of uranium can power a city.
These energy types travel through space or conductors without requiring matter to move from place to place. They're essential for communication, power distribution, and life itself.
Compare: Radiant Energy vs. Sound Energy—both travel as waves, but radiant energy is electromagnetic (travels through vacuum) while sound is mechanical (requires matter). Exam questions often test whether you know sound can't exist in space.
| Concept | Best Examples |
|---|---|
| Motion-based energy | Kinetic energy, mechanical energy |
| Position-based energy | Gravitational potential energy, elastic potential energy |
| Energy in chemical bonds | Chemical energy (food, fuel, batteries) |
| Energy in atomic nuclei | Nuclear energy (fission, fusion) |
| Particle motion in matter | Thermal energy |
| Electromagnetic waves | Radiant energy (light, radio, X-rays) |
| Electron flow | Electrical energy |
| Mechanical waves | Sound energy |
A ball is thrown straight up into the air. Describe how kinetic and potential energy change throughout its flight, and explain what happens to the total mechanical energy (assuming no air resistance).
Which two energy types are both stored within matter itself but differ dramatically in the amount of energy released? What explains this difference?
Compare radiant energy and sound energy: What do they have in common, and why can one travel through space while the other cannot?
A student claims that a cup of hot coffee has more thermal energy than a frozen lake. Explain why this claim is incorrect, using the definition of thermal energy.
Trace the energy transformations in a hydroelectric dam, starting with water stored at the top and ending with electricity in your home. Identify at least four energy types involved.