English for students of Physics_Unit 15

In both fission and fusion, unstable nuclei have become more stable. Energy is released. In order to explain these processes, we need to be able to say where this energy comes from. One answer lies in the origins of the nuclei we are considering. Take, for example, uranium. The earth’s crust contains uranium. In some places, it is sufficiently concentrated to make it worth while extracting it for use as the fuel in fission reactors. This uranium has been part of the Earth since it was formed, 4500 million years ago. The Earth formed a swirling cloud of dust...