Water, Air, Energy, and Waste Management for Environmental Sustainability Practice Test

Energy released from atomic nuclei is called nuclear energy. In fission, a heavy nucleus such as uranium-235 splits into lighter nuclei and a few neutrons. The total mass of the products is slightly less than the original mass, and that missing mass becomes energy according to E = mc^2. This is the kind of energy described here, the one commonly harnessed in reactors by maintaining a controlled chain reaction. By contrast, solar energy comes from light from the sun, geothermal energy from Earth’s internal heat, and mechanical energy relates to the motion or position of an object, not energy released from nuclei. Fusion also releases nuclear energy, but it’s fission-based energy that’s most widely used in reactors today.