calculus velocity question

Question

If a ball is thrown straight up into the air with an initial velocity of 85ft/s its height in feet after t seconds is given by y=85t - 16t^2. Find the average velocity for the time period beginning when t=2 and lasting 0.1, 0.01, 0.001

Answer 1

If f(t)=85t-16t², then for h = 0.1, 0.01 or 0.001

Average Velocity, V(h)=(f(2+h)-f(2))/h

Then the rest is just evaluating for h for each of those values. For example:

V(0.1) = (85(2.1)-16(2.1)² - 85(2) + 16(2)²)/0.1 = 19.4 ft/s

Note that V(h) can be simplified to 21-16h.

Such that V(0.1) = 21-1.6 = 19.4

V(0.01) = 21 - 0.16

V(0.001) = 21- 0.016