Easy Physics Question More Detail Please!?

Question

Alright this question uses the same exact formula, except both answers didn't explain the formula completely...

Here is the formula from my last question
"Formula for distance covered, s, is
s = ut + (1/2)at^2, where u = initial velocity and a = acceleration.
Here, u = 0 and a = 1.8 m/s^2
So, s = 0 + (1/2)(1.8)(1^2)
= 0.9 m."

^***What is the (1/2) for?***^

Here is the VERY similar question:

"A child slides down a hill on a toboggan with an acceleration of 1.8 m/s^2.

If she starts at rest, how far has she traveled in 2.0 s?"

So this is what I'd think you would plug in for the function

0 + (1/2)(1.8)(2^2), but it isn't correct and I still don't know what the (1/2) is.

Answer 1

Go back to the previous question, you will figure it out. The 1/2 comes from the fact that you are dealing with a constantly changing speed. so if you start at zero and accelerate for one second the final speed is 1.8M/s but you have not been moving at that speed for the whole time.