Chapter 19, Problem 64A

Make a Cartesian diver like the one shown below. Completely fill a large, pliable plastic bottle with water. Partially fill a small pill bottle so that it just barely floats when capped, turned upside down, and placed in the large bottle. (You may have to experiment to get it just right.) Once the pill bottle is barely floating, secure the lid or cap on the large bottle so that it is airtight. When you press the sides of the large bottle, the pill bottle sinks; when you release it, the bottle returns to the top. Experiment by squeezing the bottle different ways to get different results. Explain the behavior you see.

To determine

To Explain: The pill bottle dynamics with the application of pressure.

Explanation of Solution

Introduction:

According to Pascal’s law, the pressure applied at one point of the enclosed fluid will be transmitted to every point of the fluid without change in its magnitude.

It is mentioned that, with the application of pressure on the sides of pliable plastic bottle, the pill bottle will sink in water. The pill bottle will float by the release of pressure.

According to Pascal’s law, the pressure that is applied on the wall of the pliable plastic bottle will be transmitted to every point in the water. Because of this pressure, the water level in the pill bottle with increase.

As the density of water is more than the density of air, the pill bottle will sink.

Again, by the removal of pressure on the walls of the plastic bottle, the pressure inside the bottle will decrease which in turn decrease the water level inside the pill bottle. Therefore, the pill bottle will float again.

Conclusion:

When the pressure is applied on the wall of the pliable plastic bottle, the pill bottle will sink. This is due to the fact that the pressure is uniformly distributed within the water.