If a ball is thrown into the air with a velocity of 40 ft/s, its height in feet after t seconds is given by y = 40t - 16t2. (a) Find the average velocity for the time period beginning with t = 2 and (1) lasting 0.5 seconds: ft/s (2) lasting 0.1 seconds: ft/s (3) lasting 0.05 seconds: ft/s (4) lasting 0.01 seconds: ft/s (b) Find the instantaneous velocity when t = 2: ft/s