Final answer:
Tuesday is a proper noun because it is the specific name of a day of the week and is always capitalized.
Step-by-step explanation:
When distinguishing between proper nouns and common nouns, it's important to understand that proper nouns refer to specific names of people, places, events, and things and are always capitalized. In contrast, common nouns are general names for types of things and are not capitalized unless they begin a sentence. In the context of your question, Tuesday is a proper noun. It's the specific name of a day of the week and, as such, is always capitalized. Just as in the sentence "Mary jogged.", where "Mary" is a proper noun serving as the subject, "Tuesday" plays a similar role when it is used to describe a specific day.