The speed of light, c is constant in all reference frames and is roughly equal to 3. 00x108 meters per second. In the context of Einstein’s relativity, the c2 functions more as a unit conversion factor than a constant. As such, it is squared as a result of dimensional analysis - energy is measured in joules, or kg m2 s-2, so adding the c2 ensures that the relationship between energy and mass is dimensionally consistent.
Energy can be neither created nor destroyed, it can only take a different form. For example, coal has a lot of potential energy that turns into thermal energy when it is burned.
There are also a few other definitions of mass. There exists “invariant mass,” and “relativistic mass. " Invariant mass is mass that remains unchanged no matter what frame of reference you are in. Relativistic mass, on the other hand, depends on the object’s velocity. In the equation E = mc2, m refers to the invariant mass. This is very important, because this means that your mass does not grow as you go faster, contrary to popular belief. It’s important to understand that mass and weight are different. Weight is the gravitational force felt by an object, while mass is the amount of matter in that object. Mass can only change if the object is physically altered, while weight changes depending on the gravity of the environment the object is in. Mass is measured in kilograms (kg) while weight is measured in newtons (N). Like energy, mass can neither be created nor destroyed, but it can also change form. For example, an ice cube can melt into a liquid, but it still has the same mass in both states.
Obtaining energy this way is not very efficient and is costly to the environment.
Nuclear power is based on this principle. Nuclear reactors cause fission (the splitting of atoms) to occur and capture the massive amount of energy released.
PET scans use radioactivity to see inside the body. The equation allowed for the development of telecommunications with satellites and rovers. Radiocarbon dating uses radioactive decay based on the equation to determine the age of ancient objects. Nuclear energy provides cleaner and more efficient energy sources to our society.
