Tropical Asia

The durian is a unique tropical fruit from Southeast Asia, that grows to be larger than a human head, has a hard shell covered with sharp, piercing spikes, and has a pungent odor which instills either love or hate. When ripe, it drops from its tree, from a height ranging from 25 to 50 meters. When walking through a durian orchard, care must be taken not to be hit by falling fruit.

What is the ratio of the speed upon impact when a durian falls 50 meters, to the speed when a durian falls 25 meters instead?