The Uncle (aka Physics Guru) in coffeeshop

This uncle is able to hang the bags on the side of the table while enjoying his coffee in peace.

How did he do that?!

So as long as the wooden chopstick is strong enough, he can hang a few bags like this.

Another type of gadget to hang your bags by the table is this. As long as the centre of gravity (CG) is directly below the support area (area of the hanger in contact with the table), the bag will not fall.

It is the same working principle as most balancing toys.

What is moment?

Minimum force F to push barrel up a step

Solutions: Option D

You can view the video tutorial here or the written solutions below.
(You can click here to view another post on similar question where angle is given instead)