Derivative of position-time gives velocity-time. Derivative of velocity-time gives acceleration.
Well, we know the acceleration.
So now if we take the integral of acceleration, we get velocity.
And we know that at 0 seconds, we're traveling -20ft/s
And so we get:
The integral of this will then give us distance:
And we know that we are 245 feet up at 0 seconds.
And thus our final equation:
You may recognize this last equation from physics class.
d = (vi)t + 1/2at^2
In the form of d - 245