Hertz measures cycles per second - one Hertz is one cycle per second. Unlike gauss that is a measurement unit for the strenght of a specific thing (an electromagnetic field), hertz is a generic frequency measurement.
Prepend is a word that means to attach content as a prefix. It is often used in different kinds of programming and in automated processes. Some prepending is done manually as a user. For example, a prepend command could be used in a scripting language that a programmer would enter into a certain function or code module. It would add certain characters of text to the beginning of some variable or object.
In English grammar, the object of a preposition is a noun, noun phrase, or pronoun that follows a preposition and completes its meaning. The object of a preposition is in the objective case. A word group made up of a preposition, its object, and any of the object's modifiers is called a prepositional phrase. In contemporary language studies, the object of a preposition is sometimes described as a prepositional complement. See Examples and Observations below.