One-to-One Functions

Jonny is riding a rollercoaster that looks exactly like the picture above. The rollercoaster is going $100$mph. Jonny throws his hands up and feels the wind in his face, but all Jonny can think about is if the roller coaster makes a graph of a function. He decides the graph is a function, but he doesn't know which kind of function. Tell Jonny which kind of function the track of the rollercoaster in the picture above is.