# What does y with a line over it represent?

I've been asked to complete this chart and have never come across this symbol before, nor can I find anything about it on google:

http://postimage.org/image/oe7hb9cy3/

What does the y with the line over it represent? And also, does the the t^2 column just mean square all of the time values for each row?

-
The $\bar{y}$ is an average for y. I guess that last column is indeed just squaring the time values, but its not clear why. – DJBunk Jan 24 at 14:29
The time squaring is so you draw a straight line instead of a parabola. – Qmechanic Jan 24 at 14:33
@DJBunk There are subsequent steps that rely on those values once the graph is filled. I just have to make sure it's filled out with the correct values or all of the other following steps are going to be incorrect. – Scotty Jan 24 at 14:33
Please vote to migrate to either maths or computational science – Larry Harson Jan 24 at 18:01

$\bar{y}$ means the mean of the $y$ values. For each time value, you want to take the mean of the five $y$ measurements to get a best value.
$t^2$ is just the square of the time. You want to do this because you will be plotting $y$ versus $t^2$. You expect $y \propto t^2$, so plotting that will give you a straight line. You can then fit that straight line to get the proportionality constant.