-- The acceleration of gravity (on Earth) is 9.8 m/s².
-- That means that during every second an object falls,
it adds 9.8 m/s of speed.
Now ! If it adds 9.8 m/s of speed every second, then
how fast is it falling at the end of 3.4 seconds ?
This is as close as I can bring you to the answer
without dropping it at your feet, or handing it to you
on a golden tray.