If a ball is thrown straight up into the air with an initial velocity of $80$ ft/s, its height in feet after $t$ seconds is given by $$y=80t−16t^2$$ Find the average velocity for the time period beginning when $t=1$ and lasting
(i) $0.5$ seconds
(ii) $0.1$ seconds
(iii) $0.01$ seconds
Finally, based on the above results, guess what the instantaneous velocity of the ball is when $t=1$.