Symbols are a language that allows us to talk with precision about the relationships in a problem. As with any language, we all need to agree to use words or symbols in the same way if we want to communicate with each other. Many of the ways we use symbols in science and engineering are somewhat arbitrary, often reflecting historical roots. Nonetheless, practicing scientists and engineers have come to agree on how to use the language of symbols. Learning this language is part of learning physics.
We will use subscripts on symbols, such as , to designate a particular point in the problem. Scientists usually label the starting point of the problem with the subscript “0,” not the subscript “1” that you might expect. When using subscripts, make sure that all symbols referring to the same point in the problem have the same numerical subscript. To have the same point in a problem characterized by position but velocity is guaranteed to lead to confusion!