A stone is dropped from the top of a tower. What is its velocity after 3.0 seconds?

For purposes of completing our calculations, we're going to assume that

the experiment takes place on or near the surface of the Earth.

The acceleration of gravity on Earth is about 9.8 m/s², directed toward the

center of the planet. That means that the downward speed of a falling object

increases by 9.8 m/s for every second that it falls.

3 seconds after being dropped, a stone is falling at (3 x 9.8) = 29.4 m/s.

That's the vertical component of its velocity. The horizontal component is

the same as it was at the instant of the drop, provided there is no horizontal

force on the stone during its fall.