A chunk of ice breaks off a glacier and falls freely through 30.0 m before it hits the water. How long does the fall take?

1. Identify the knowns: the initial position is 0, the final position is -30.0 m, the initial velocity is 0 and the acceleration is -9.80 m/s^2. 2. With zero initial velocity the displacement equals minus half the acceleration due to gravity times time squared. 3. Rearranged, the time squared equals twice the displacement divided by the negative of the gravitational acceleration. 4. Substitute the values: 2 x (-30.0 m) / (-9.80 m/s^2) = 6.12 s^2. 5. Take the square root and keep the positive root: the time is 2.47 s. 6. Quoting 6.12 s reports the time squared without taking the square root. _Source: OpenStax College Physics (CC BY 4.0), Ch 2 "Kinematics", section 2.7 Falling Objects_