How long for rock to hit ground

Question

rock is thrown 5 feet into air with initial velocity of 16ft/sec

(h)t=-16t^2 + 16t +5

how long for rock to reach ground

is this a correct solution

0=-16t^2 + -16t +5

0 = 16t - 16 - 5

21=16t

1.3125=t

Thanks

Answer 1

You need to solve for the positive value of t in the equation

h(t) = -16t² + 16t + 5 = 0

Using the quadratic formula,

t = 1.25 sec

Plug this number back into the equation and see that it is the solution. Your solution is incorrect because you divided by t incorrectly in the second line. You need to use the quadratic formula for this type of problem.

Answer 2

To get height: h=-16.1*t^2+vt+s.

Falling= (t^2+t)/2*32.2.

Metric= " " 9.81