For this case what you must do is replace the value of the height in the given equation and clear the value of t. We then have to replace: s = 16 * t ^ 2 315 = 16 * t ^ 2 Clearing the value of t: 315 = 16 * t ^ 2 t1 = root (315/16) t1 = 4.437059837 t2 = - root (315/16) t2 = - 4.437059837 We ignore the negative root. Answer: it will take him, falling freely 4.43 s to reach the ground
