Interesting riddles #2

I bring you the answers as I promised. Norwegian drinks water, German owns fish. Here is another dose.

Problem:
You have 2 tubs and infinity amount of water. The first one is with 5L and the second with 3L volume.
Question:
How to measure out exactly 4L?

Problem:
There are 8 balls of the same size. However one's weight is different (heavier or easier).
Question:
How to come out with the different one with only two measure given?

Next article will answer it, will you?