An earthquake causes a 3 kg book to fall from a shelf. If the book lands with a speed of 4.0 m/s, from what height did it fall?

Given:

3kg book

speed of falling of 4.0 m/s

acceleration due to gravity - 9.8 m/s²

Vf² = Vi² + 2 * a * d

Vf = final velocity; Vi = initial velocity; a = acceleration; d = distance

0² = (4 m/s) ² + 2 (-9.8m/s²) * d

0 = 16 m²/s² - 19.6 m/s² * d

-16 m²/s² = - 19.6 m/s² * d

-16 m²/s² / - 19.6 m/s² = d

0.82 m = distance

The 3 kg book fell from the a shelf at the height of 0.82 meters.