The acceleration is the slope of the v/t graph.
-- If the graph is a straight line, then pick any piece of the line, or even the whole graph, and divide (change in 'y') by (change in 'x') for the piece you chose.
-- If the graph is a curve or a squiggle, then you can do the same thing with a piece of it, and you get the average acceleration during that piece.
-- If you need the acceleration at one point on the graph, you have to lay a straight line against that point on the graph, and find the slope of that straight line.
