A ball is dropped out of a window and hits the ground at 14.5 m/s. How long did it take to fall to the ground?

Explanation:

Use the one-dimensional equation:

which says that the final velocity of a falling object is equal to its initial velocity times the acceleration of gravity times the time it takes to fall. We have the final velocity, -14.5 (negative because its direction is down and down is negative), initial velocity is 0 (because it was held still by someone before it was dropped), and acceleration is -9.8 (negative again, because direction is down while acceleration increases). Filling in:

-14.5 = 0 - 9.8t and

-14.5 = -9.8t so

t = 1.5 seconds

3.2x10^7