If the plotted points on a speed-time graph do not form a straight line, what do you know about the object's acceleration?

Question

stamp · Answer

The acceleration is not constant.

stamp · Answer

The rate of change of velocity, or change in velocity / change in time, is acceleration. 

So the slope of a velocity vs time graph is actually a description of acceleration.

On a straight line graph, the slope is always the same. On non-linear graphs, slope is variable and changes depending on where you are on the line.

So if you graph is not a straight line, it has variable acceleration at different points.

stamp · Answer

I hope that makes sense.