I will derive

At first I was afraid, what could the answer be?
It said given this position find velocity.
So I tried to work it out, but I knew that I was wrong.
I struggled; I cried, "A problem shouldn't take this long!"
I tried to think, control my nerve.
It's evident that speed's tangential to that time-position curve.
This problem would be mine if I just knew that tangent line.
But what to do? Show me a sign!

So I thought back to Calculus.
Way back to Newton and to Leibniz,
And to problems just like this.
And just like that when I had given up all hope,
I said nope, there's just one way to find that slope.
And so now I, I will derive.
Find the derivative of x position with respect to time.
It's as easy as can be, just have to take dx/dt.
I will derive, I will derive. Hey, hey!

And then I went ahead to the second part.
But as I looked at it I wasn't sure quite how to start.
It was asking for the time at which velocity
Was at a maximum, and I was thinking "Woe is me."
But then I thought, this much I know.
I've gotta find acceleration, set it equal to zero.
Now if I only knew what the function was for a.
I guess I'm gonna have to solve for it someway.

So I thought back to Calculus.
Way back to Newton and to Leibniz
....

Me lo encontré en Coudal :-D