Question 120158
The initial height, s, is 300 feet, and the final height is 0, because you are concerned with the time it takes to hit the ground.


So, your equation becomes:


{{{-16t^2+300=0}}}


Add -300 to both sides and then multiply by -1:


{{{16t^2=300}}}


Take the square root of both sides:


{{{4t=sqrt(300)}}}  (you can ignore the negative square root because you are looking for a positive time value)


Divide by 4:


{{{t=sqrt(75)}}}


But {{{75=3*25}}}, so {{{sqrt(75)=5*sqrt(3)}}}


Hence, {{{t=5*sqrt(3)}}} seconds.


Hope this helps,
John