If a ball is thrown straight up into the air with an initial velocity of 85 ft/s, its height in feet after t second is given by y=85t-16t. Find the average velocity for the time period beginning when t= 1 and lasting (1) 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.