Shown here is a speed$-$time graph for a cart that was given a quick push, moved along a track, bounced back off a rubber band, and returned to its starting point.

$5.$ Mark an $\backslash ($ X $\backslash )$ on the graph at the point where you think the hand lost contact with the cart after the initial push. Briefly explain how you know.

For convenience the graph has been divided into six sections, labeled A$,$ B$,$ C$,$ D$,$ E$,$ and F$.$ Answer each of the questions below by choosing as many or as few segments as you think appropriate. You must also briefly briefly explain your choice$($s$).$

$6.$ Which sections of the graph provide evidence that the cart was an energy receiver in an interaction?

$7.$ Which sections of the graph provide evidence that there was a force acting on the cart in the opposite direction to its motion?

$8.$ Over which sections do you think the cart was interacting with the rubber band?