Answer:
9.5 seconds.
Explanation:
We know that the equation that represents the height of the penny as a function of time is:
h(t) = -16*t^2 + 1451
Where the height is in ft, and the time is in seconds.
a) We want to know how long takes the penny to hit the ground.
Well, the penny will hit the ground when its height is equal to zero.
Then we need to solve for t:
h(t) = 0 = -16*t^2 + 1451
0 = -16*t^2 + 1451
16*t^2 = 1451
t^2 = 1451/16 = 90.7
t = √90.7 = 9.5
This means that it takes 9.5 seconds to hit the ground.