Which One Will Be Full First?

Puzzle : Which One Will Be Full First?

Here is another puzzle for you to solve today.
This is little different than any other puzzle you generally get.

Crack your brain and tell which one will be full first , is it box 1, 2, 3 or 4?

Spend some time and think out of box to get the answer,
if you have been good in Physics you should not take much time to resolve it with the logic.

Do share this with friends and see if they have the answer!!

Note : To see answer/hint of this puzzle, please scroll below and click on next page