Question

If a ball is thrown straight up into the air with an initial velocity of 40 ft/s, it height in feet after t second is given by y = 40 t - 16 t^2. Find the average velocity for the time period begining 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 is the instantaneous velocity of the ball is when t =1?