Question 772793
h=-16t^2 + 60t
<pre>
Plug in 36 for h, then simplify and solve that quadratic 
equation for t

You'll get two answers, t=3/4 and t=3.

It will be at a height of 36 feet first in 3/4ths of a second

It will also be at a height of 36 feet again in 3 seconds.

One answer is when the cannonball is going up, and the other 
answer is when it is coming down.

He wants the answer when it FIRST was at that height (when going up),
so it's 3/4 of a second.

Edwin</pre>