A ball is thrown from an initial height of 6 feet
with an initial upward velocity of 36 ft/s.
(a) After how many seconds did it hit the ground?
(b) After how many seconds did it reach its maximum
height?
(c) What was its maximum height?
The formula is
where h0 = initial height = 6 feet
where v0 = initial velocity (upward if positive) = 36 ft/s
(a) After how many seconds did it hit the ground?
We set h(t) = 0 and solve for t
Divide through by 2
That doesn't factor, so we use the quadratic formula,
and find it has only one feasible (positive solution,
approximately 2.4 seconds later.
(b) After how many seconds did it reach its maximum
height?
We use the vertex formula 
for the horizontal coordinate
of the vertex:
, 
,
seconds.
(c) What was its maximum height?
We substitute 
seconds for t in
feet.
Edwin
