# Solving the Submarine Problem: Will it Rise or Sink?

• raul_l
In summary, the conversation discusses the scenario of a scuba diver and a submarine underwater, where from the scuba diver's perspective, the submarine appears to be getting heavier, while from the submarine's perspective, everything else seems to be getting heavier. This is known as Supplee's paradox and has been discussed in various sources. The results can be explained from different viewpoints, but it is generally agreed that if the submarine moves at relativistic velocities, it will sink assuming it generates no lift forces.
raul_l
Suppose with have two objects underwater: a scuba diver and a submarine that travels close to the speed of light. For the scuba diver is seems that the submarine is getting heavier and from the submarine it seems as if everything else is getting heavier.
So which is it - will the submarine rise to the surface or sink to the bottom?

I kinda get the feeling that I'm missing a lot of factors here so any help would be welcome. :)

raul_l said:
Suppose with have two objects underwater: a scuba diver and a submarine that travels close to the speed of light. For the scuba diver is seems that the submarine is getting heavier and from the submarine it seems as if everything else is getting heavier.
So which is it - will the submarine rise to the surface or sink to the bottom?

I kinda get the feeling that I'm missing a lot of factors here so any help would be welcome. :)

This is known as Supplee's paradox. It's been discussed here before (look for Supplee), it's also discussed in the wikipedia http://en.wikipedia.org/wiki/Supplee's_paradox and at this physical review focus article http://focus.aps.org/story/v12/st4, which has a link to a physical review letters paper (which you'll need to access from a library, unfortunately).

There are several different ways of explaining the results from various viewpoints, but everyone agrees that the submare was at neutral buoyancy at rest, if it moves at relativistic velocities it sinks, assuming that it generates no lift forces, i.e. assuming that it imparts no upward or downward momentum to the fluid via its passage.

Thanks.
I feel kinda stupid for posting this before searching the web.

## 1. Will a submarine sink or rise when it is underwater?

A submarine is designed to be able to do both. It can control its buoyancy by adjusting the amount of water in its ballast tanks. When the tanks are filled with water, the submarine will sink. When the tanks are emptied, the submarine will rise to the surface.

## 2. How does a submarine stay underwater?

A submarine uses its ballast tanks and diving planes to control its buoyancy and maintain a certain depth. It also has propulsion systems, such as propellers and pumps, to move through the water and maintain its position.

## 3. What factors can cause a submarine to sink?

A submarine can sink due to a variety of factors, including human error, mechanical failure, or damage from external forces, such as collisions or explosions. Changes in water pressure and temperature can also affect a submarine's buoyancy and potentially cause it to sink.

## 4. How do scientists and engineers ensure that a submarine will not sink during operation?

Before a submarine is put into operation, it undergoes rigorous testing and simulations to ensure its design and systems are functioning properly. Engineers also factor in safety measures, such as redundancies and emergency procedures, to minimize the risk of sinking. Regular maintenance and inspections also help to prevent potential sinking incidents.

## 5. Can a submarine sink to the bottom of the ocean?

Yes, a submarine can sink to the bottom of the ocean if it loses control of its buoyancy or encounters a catastrophic event. However, most submarines are designed to withstand extreme depths and have emergency systems in place to help bring them back to the surface in case of an emergency.

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