Believe it or not gravity is not really a force, it is an acceleration and on Earth it is about 32 feet/sec2. This same science principle applies in decelerating devices like parachutes and parafoils. The parachute decelerates or slows down the fall of the object.
What is a .DS_Store or ._ AppleDouble file? .DS_Store files are created by OS X to store metadata about folders and files including viewing options, icon positions and color labels. ._ AppleDouble files are created by the OS X when an application adds resource data or metadata to a file on a disk whose format doesn't support resources or metadata.
In a nutshell, iCloud is more than just a cloud storage solution that gives you the first 5GB of storage for free; you can use it to store songs, apps, and e-books you've purchased from the iTunes App Store or photos shot with your device, on Apple's servers.