How to find displacement in a position v time graph?

[deaninator]

Homework Statement

What is the displacement between 15 and 20 seconds? At 15 seconds the position is 51 meters and at 20 seconds the position is 60 meters. It is a constant velocity between 15 and 20 seconds. The answer is 9 meters but I have no idea how my teacher came to that. Thanks!

Homework Equations

The Attempt at a Solution

 

[kjohnson]

It doesn't matter if its constant velocity, constant acceleration, etc. They just want to know how far the object displaced over that time. So your just taking the displacement at time 'b' minus the displacement at time 'a'.

60m-51m=9m

 

[deaninator]

It doesn't matter if its constant velocity, constant acceleration, etc. They just want to know how far the object displaced over that time. So your just taking the displacement at time 'b' minus the displacement at time 'a'.

60m-51m=9m

Thanks!