This is the video we did in our class. The idea is that you check the amount of water (VOLUME) displaced when we introduce the glass with rocks. Depending on the weight of this glass if the volume is the same than upthurst the glass will float.
The second time when I introduce more rocks the volume and the weight of the glass is practically the same, it’s close to sink.
This is a cargo being loaded. You can see the amazing control of the weight in this huge ships.