Question

PLEASE HELP In this graph of displacement vs time http://i.imgur.com/uoHGw.png
A. the acceleration and velocity are always positive B. the velocity is first negative and then positive
C. the acceleration is first negative and then positive D. the acceleration is positive, and the velocity changes from negative to positive. I think its A

Answer 1

Im wondering what about the concept you dont understand?

Answer 2

this is displacement, you see that it is always increasing (heading up) so we know the velocity is positive
now the question is what about acceleration?
you are supposed to look at the graph and ask is it concave up (leaning left) concave down (leaning right) or does it change concavity