The formula s= 16t ^2 is used to approximate the distance S, in feet, that an object falls freely from rest. How long would it take for an object to fall from the top? Solution Your question is missing the height from which the object falls. Let\'s let that equal H. So after the object reaches the ground it will have traveled H feet which is the value for s. We can solve for t. H = 16t^2 H/16 = t^2 (Divide both sides by 16) t= sqrt(H/16) = sqrt(H)/4 (Take the positive square root of both sides. We ignore the negative root because t is not defined in this problem for negative values/) So once you know H, you can answer the problem by taking the square root and dividing by 4..