Final answer:
Word stress patterns in English can be influenced by the base word, suffixes, phonological rules, and syllable structure, not necessarily the prefix. 'Contribute' and 'contemplate' have different stresses due to the base words and suffixes they contain.
Step-by-step explanation:
The stress patterns in words like contribute and contemplate depend on various phonological rules in English, including the origin of the word, the syllable structure, and the position of the stressed syllable in the base word before any prefixes or suffixes are added. The prefix 'con' doesn't inherently dictate the stress pattern of the words it begins; rather, it's the base word or suffix that most often influences where the stress falls. The word 'contribute' has its stress on the second syllable (tri), while 'contemplate' has the stress on the first syllable (con). Other factors can influence word stress as well, such as the 'weight' of syllables (whether they end in a vowel or consonant) and the form-class of the word (whether it's a noun, verb, etc.).
In the context of spelling and pronunciation rules discussed in the provided reference information, these rules typically refer to how certain letters or combinations of letters will affect the pronunciation and spelling of word parts when prefixes, suffixes, or base words are influenced by various phonological or orthographic factors.