Reading a Speed vs Time Graph - acceleration
In the same way that speed = distance divided by time, we can also look at acceleration
as the change in speed over the time that the
change occurred. Both of these quantities can be
thought of as rates of change or ‘slopes’ on a
graph like the one to the left.
When the final speed is, larger than the initial speed, the slope of the line is positive
(upward) and we say that the object is
accelerating. When the final speed is less than the
initial speed, the slope is negative (downward)
and we say that the object is decelerating.