Explaining the Differences Between Two Graphs for a Roller Coaster Cart's Motion

[Genxi]

Homework Statement

A proposed ride at the amusement part launches a roller coaster car up an inclined track. Near the top of the track, the car reverse direction and rolls backwards into the station...

Homework Equations

My question is: What is the difference between, "Sketch a graph of the instantaneous acceleration vs. time graph you expect for the cart as it rolls up and then back down the track after an initial push" and this, "Sketch a second instantaneous acceleration vs. time graph for a cart moving up and then down the track with the direction of a constant acceleration always down along the track after an initial push?"

The Attempt at a Solution

Hi there,

I am working on a physics question, but I am stuck due to the wording. As I am unable to get hold of my instructors and my limited schedule to finish it in the next few days, I must finish this now.

From my understanding, the second graph asks for gravity to apply to the condition...but wouldn't gravity be needed for the cart in the first graph to roll back down? Please, please do not give me an answer. Not only is this a simple problem, I want to learn everything myself. If possible, please reword these two sentences in an understandable manner in order for me to move on.Thanks!

 

[voko]

Hmm. I do not see how the two graphs might differ.