find the average speed of the ball

[coolbeans33]

the height in ft of a baseball, t seconds after being thrown straight upward, is given by h(t)=36t - 16t^2

1) find the average speed of the ball for
a) 0≤ t ≤1
b) .5≤ t ≤ 1
c) .9 ≤ t ≤1

the answer to a) is 20 ft/sec, which is what you get if you plug 1 into the equation. the answer to b) is 12 ft/sec, and c) is 5.6 ft/sec.

how the heck did they get these answers?? I just don't get it. please explain how to do this step by step

 

[Bob Brown MSEE]

formula for average speed

a) 0≤ t ≤1
(h(1) - h(0))/(1-0)
b) .5≤ t ≤ 1
(h(1) - h(0.5))/(1-0.5)
c) .9 ≤ t ≤1
(h(1) - h(0.9))/(1-0.9)

 

[DrPhil]

a) 0≤ t ≤1
(h(1) - h(0))/(1-0)
b) .5≤ t ≤ 1
(h(1) - h(0.5))/(1-0.5)
c) .9 ≤ t ≤1
(h(1) - h(0.9))/(1-0.9)

That is

\(\displaystyle \displaystyle \dfrac{h(final) - h(initial)}{t(final) - t(initial)} \text{ or }\dfrac{\Delta h}{\Delta t}\)