Inertia everywhere

For the following experiment you need:

Experiment 2b:

First empty the tub and dry it well. Fix the thread with the help of the needle (pierce a whole and fasten with knots) or with the help of an adhesive tape on the table tennis ball. Then paste the other end of the thread with a second adhesive tape in the middle of the tub on the ground, so that the upper end of the TT-ball is half way up the tub if the string is tight (compare to the picture below). Then fill the tub again with water until the TT-ball is covered if the string is tight. The TT-ball should rise in the water now (see picture below).

What will happen with the TT-ball, if you suddenly pull the tub in your direction?

a) The ball will also move towards me.

b) The ball will stay in rest and will not move.

c) The ball will move in the opposite direction (away from me).

First make an assumption about the result of the experiment, then check your assumption by pulling the tub fitfully to you. (Pay attention not to slop the water). Due to the fact that the effect passes quickly again, it is advantageous to ask a friend to move the tub so you can watch. It's the best, if you do the experiment several times.