When something is saved to your hard drive it is engraved into a small disk, when you delete an item you are simply telling your computer "its safe to re-write here" and as such it can take quite a bit of time to write over your file at which point it will be gone/too corrupted … Read more

Because the average commercial jet moves at about 465 mph  stopping mid flight would kill everyone on board, as well as rip the plane to pieces. Otherwise  we wouldn't need airports.