The distance an object falls is directly proprtional to the square of the time it has been falling. After 8 seconds it has fallen 2304 feet. How long will it take to fall 900 feet?

S =k t^2.

2304 =k*8^2.

900 =k*t^2.

2304/900 =8^2/t^2.

t^2=(64*900)/2304.

t^2=25.

t=5 sec.