Hi! Please help... a woman drops a front door key to her husband from their apartment window several stories above the ground. the function h=-16t^2 +64 gives the height h of the key in feet, t seconds after she releases it.
A/ how long does it take the key to reach the ground?
B/ what are the reasonable domain and range for the function h?

Question

anonymous · Answer

that is a typical physics question :)

anonymous · Answer

a. solve for -16t^2 +64 = 0 
-16t^2 = -64 
t^2 = 4
t = 2 seconds

anonymous · Answer

thank you.!  and what would be part B?

anonymous · Answer

my error was that i stayed in √4 lol

anonymous · Answer

D: $[0,2]$
R: $[0,64]$

anonymous · Answer

how would i be getting to that conclusion?

anonymous · Answer

The key hits the ground at 2 seconds. Therefore, we are only concerned with those 2 seconds. 

The key travels from 64 feet above the ground to the ground. (Set t=0 to find the initial height.) So we are only concerned with those 64 feet.

anonymous · Answer

Oh ok thanks !