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I tried to do this experiment recently at school and my house. I started the experiment by having three same type of bottles with the labels A,B and C. Bottle A has been fully filled with water, Bottle B has been half-filled with water and Bottle C is kept empty.

Then I started flipping the three bottles with the same number of tries. Then, I realized that

1) Bottle A and Bottle C will always flip more than 1 turn meaning more than 360 degree.

2) Bottle B will always flip less than 1 turn, meaning less than 360 degree (minimum 180 degree til maximum 270 degree).

So, my question is why it happens (with bottle B)? I think it is because of the quantity of water. But why?

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In the cases of Bottle A and Bottle C, they are full and empty. So the amount of water in them (or not) can be considered to be a complete system along with the bottle, since there is no possible way in which the fluid in the full bottle would reduce its volume or overall distribution, certain properties like the system's center of mass,center of gravity and its overall mass distribution stays constant.

But considering bottle B, when you try to flip it, the centrifugal force created by the force you apply causes the quantity of water in the bottle to shift, which causes a shift in its center of gravity, and a change in its mass distribution, which can cause an overall change in the bottles rotation.( The moment of inertia of the body changes. The moment of inertia is a property which is analogous to mass, which is used to study rotation. A body with more moment of inertia would rotate less freely and vice versa). So it indeed is because of the quantity of the water in the bottles.

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So we have than with a mixture of water and air we have more energy dissipation? One possible reason is this: the B bottle is assymetric, with the heavy watered side down. While it turns, water shpuld turn sides. Because of the viscosity of the water nd n relation with the glass, water has to exert a work, thus losing energy

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