Q & A: Water pressure

Q: If water, as a liquid, cannot be compressed, then why are there such immense pressures at the bottom of the ocean? Why, if you fill an airtight (or watertight) container with it at the bottom of the ocean, does it expand and explode? Is my logic bad?

A: Your logic is actually quite sound, and your question brings up an interesting point about the behaviour of water under pressure.

1. Water's Incompressibility

It's true that water, as a liquid, is generally considered to be incompressible. This means that under normal circumstances, you can't significantly reduce its volume by applying pressure. This is why when you fill a container with water on the surface and then dive with it to the bottom of a swimming pool, for example, the volume of the water in the container remains roughly the same.

2. Pressure Underwater

However, the immense pressures at the bottom of the ocean are due to the weight of the water above pressing down. The deeper you go underwater, the more water there is above you, and this creates greater pressure. This pressure affects everything submerged in the water, including any containers.

3. Effects of Pressure on Contained Water

When you take a container filled with water down to the depths of the ocean, the water inside experiences the same external pressure as the water outside. Normally, water can't be compressed, so it seems counterintuitive that the container would "squeeze" the water.

4. Exploding Containers

The reason containers filled with water might explode at extreme depths is not because the water itself is being compressed, but rather because the container is not strong enough to withstand the external pressure.

Here's what happens:

• As you descend, the pressure outside the container increases.
• If the container is not built to withstand this pressure, it will start to deform.
• The container will compress, reducing its volume, and this reduction in volume puts pressure on the water inside.
• The water inside the container cannot be compressed, so the pressure builds up significantly.
• Eventually, if the pressure differential between the inside and outside becomes too great, the container will fail catastrophically, often resulting in an explosive release of water.

So, it's not the water itself that's being compressed, but rather the container failing under the external pressure, causing the water to "expand" outward rapidly.

5. Water's Behaviour in Diving and Submarines

This is also why divers and engineers designing submarines have to take immense care in designing their equipment. Diving deeper requires stronger materials for suits and vessels to prevent compression-related injuries or structural failures.

In summary, your logic is not bad at all! The key is understanding that while water itself doesn't compress, the external pressure at the bottom of the ocean affects the container holding the water, leading to potential explosive failures if the container is not properly engineered to withstand the pressure.

Source: Some or all of the content was generated using an AI language model