Posted by Amy on .
An object is launched upward from the ground with an initial vertical velocity of 40 feet per second. After how many seconds does the object reach a height of 25 feet? I need to use the vertical motion model. Here is my work so far.
h = 17t^2 + 40t + 25

Algebra 
Amy,
I meant 16t^2

Algebra 
Reiny,
your opening function should be
h = 16t^2 + 40t
h is supposed to have a value of 25
25 = 16t^2 + 40t
16t^2  40t + 25 = 0 , looks like a perfect square
(4t  5)^2 = 0
4t = 5
t = 5/4
it will take 5/4 seconds
I don't know what "vertical motion model" means, never heard that term