What is the object of preposition in this sentence?

*The prepositional phrase is in bold for you

The car is racing around the track

The object of the preposition in this sentence is "track". The prepositional phrase "around the car" is modifying the verb "is racing" so it is acting as an adverb.

Prepositional phrases are a group of words that start with a preposition, in this case "around", followed by an object. Prepositional phrases are a part of speech that can modify nouns (adjectival phrase) or verbs (adverbial phrase).