Question 706424
h = -16t^2 + 56T + 4
set h to 28 and solve for t:
28 = -16t^2 + 56T + 4
-28 = 16t^2 - 56T - 4
0 = 16t^2 - 56T + 24
0 = 2t^2 - 7T + 3
factoring the left:
0 = (2t-1)(t-3)
t = {.5, 3}
Time in above 28 feet then:
3 - .5 = 2.5 seconds