Koichi: Bob now has a water container which is an empty container. And also we have an air gun. And from this cylinder there is an air exit here and Bob can squeeze the air out of this. We will demonstrate how this water container will move with the force of the air. [Demonstration]
Koichi: Okay as you saw with the empty or the filled with the air, this drink bag moved pretty quickly. And now we have another bag which is filled with water and looks the same but inside is filled with water so the mass is different. Now we will demonstrate the same thing with this water bag. [Demonstration]
Koichi: And as you can see with the higher mass this bag did not move as quickly as the other bag with the air. We will do that again. [Demonstration]
Koichi: Okay so that was the demonstration and you saw the difference between the air filled bag and the water filled bag. Since the masses are different you saw the difference in acceleration as a result from the same forced applied to the bag.
Title: Which bag do you think is empty (less mass) and which one is full (more mass)?