Find Minimum Acceleration from Graph

[dumakey1212]

So this looks really easy, but I can't get the right answer. It asks you to find the minimum acceleration from the graph: http://s22.postimg.org/f5dutd5ap/pic.png. This is of course the point where the slope is the smallest, and this is from t = 3-4 s or t = 4-5 s, depending on whether you want to find the positive/negative acceleration. Either way it's about (57 m/s - 55 m/s)/1 s, 2 m/s². It doesn't accept this answer or 1, 3, 4, 5 or the negatives of those. I'm not sure what's going on, this is pretty basic. There's no way the lowest acceleration is greater than 5, and it is most obviously based on the graph about 2 or 3.

 

[jedishrfu]

Did you try 0? That's the slope at 4 secs.

 

[dumakey1212]

Yup! You're right, how foolish of me :D

 

[jedishrfu]

I don't think it was foolish, after all they did say minimum acceleration which you interpreted as more negative it is the smaller it is (in a purely mathematical sense) vs the minimum magnitude of the acceleration (always a non-negative number).

Understanding where you went wrong will help you in many other problems ala "fool me once shame on you, fool me twice shame on me".