If a ball is thrown straight up into the air with an initial velocity of 100 ft/s, its height in feet after t seconds is given by y=100t-16t². Find the average velocity for the time period beginning at t=1 and lasting the following number of seconds. Answer exactly.
a) 0.1 seconds
b) 0.01 seconds
c) 0.001 seconds
d) 1 second