What is the best type of graph to model the speed of a rollar coaster the full two minutes it takes to complete the ride?

Answer 1

A line graph.

The y-axis would be speed;

For the x-axis, it could be time (showing how the speed varies with time [so far] of the ride).

The x-axis could also use distance as the track will be of a fixed length (showing how the speed varied with distance [travelled so far] on the ride), but the question refers to the two minutes of the ride, hence the suggestion above.

Answer 2

The simplest would be to have a line graph with the 2-minute time span on the horizontal axis and the instantaneous speed on the vertical axis. However, this will not show one of the key characteristics of a roller coaster ride: whether you are ascending, descending or in level motion. This can be addressed in two ways. You could colour-code the graph so that the it ranges from bright red (steep ascent) through purple (level) to bright blue (steep descent). But such a graph will not be accessible to some people with visual problems and you may wish to consider, instead, the width of the line.