Pipes in your system will have a C-Factor to help determine this loss. This is a measure of the roughness of the interior of the pipe that creates this friction. Different types of piping will have a different C-Factor, and the higher the C-Factor, the smoother the pipe.
A motif is a literary term that is an idea, object, or concept that repeats itself throughout a text. A motif gives clues to theme or reinforces ideas an author wants to emphasize. A motif generally reinforces the theme of the text. A motif must be repeated throughout a text to be considered a motif.
In literature, theme refers to the main idea or moral of the story. Sometimes this main idea or moral is stated directly, and sometimes the reader has to think about the main idea. In most literary works, there could be more than one theme. Novels and plays, especially, are long enough that different readers could pick up on different thematic ideas throughout. It is best to state the theme in a sentence.