forklare det her?

The vertical drop of the cannonball at the end of successive seconds, the lengths of the vertical lines ci, df, eh are the same vertical distances fallen by something dropped from rest. If you drop a cannonball over a cliff it will fall 5 meters in the first second, if you fire it exactly horizontally at 100 meters per second, it will still fall 5 meters below a horizontal line in the first second. Meanwhile, its horizontal motion will be at a steady speed (again neglecting air resistance), it will go 100 meters in the first second, another 100 meters in the next second, and so on. Vertically, it falls 5 meters in the first second, 20 meters total in two seconds, then 45 and so on.

jeg forstår godt at hvis der ikker er noget modstand i vandret retning så vil den blive ved med at bevæge sig med 100 meter i sekundet,

men jeg forstår ikke det med 5, 20 og 45, hvad mener han med det?

og det her forstår jeg heller ikke : The vertical drop of the cannonball at the end of successive seconds

nogle der vil forklare det?