# How do Submarines work?

## Buoyancy Subtopic #1

­"A submarine or a ship can float because the weight of water that it displaces is equal to the­ weight of the ship. This displacement of water creates an upward force called the buoyant force and acts opposite to gravity, which would pull the ship down. Unlike a ship, a submarine can control its buoyancy, thus allowing it to sink and surface at will.

To control its buoyancy, the submarine has ballast tanks and auxiliary, or trim tanks, that can be alternately filled with water or air (see animation below). When the submarine is on the surface, the ballast tanks are filled with air and the submarine's overall density is less than that of the surrounding water. As the submarine dives, the ballast tanks are flooded with water and the air in the ballast tanks is vented from the submarine until its overall density is greater than the surrounding water and the submarine begins to sink (negative buoyancy)."

I think that this website picked a good topic to talk about. Buoyancy is the most important factor because its what keeps the submarine a submarine. If the submarine didn't have buoyancy then it would sink to the ocean floor. (Brian Marshall)

## Commentary #1

This information from the website how stuff works pretty much sums up the buoyancy of the submarine. It has everything that I needed for that subtopic the information is spot on and it has good wording. I think the author of the website did a good job.

## Diving and Surfacing Subtopic #2

"A submarine or a ship can float because the weight of water that it displaces is equal to the­ weight of the ship. This displacement of water creates an upward force called the buoyant force and acts opposite to gravity, which would pull the ship down. Unlike a ship, a submarine can control its buoyancy, thus allowing it to sink and surface at will.

To control its buoyancy, the submarine has ballast tanks and auxiliary, or trim tanks, that can be alternately filled with water or air (see animation below). When the submarine is on the surface, the ballast tanks are filled with air and the submarine’s overall density is less than that of the surrounding water. As the submarine dives, the ballast tanks are flooded with water and the air in the ballast tanks is vented from the submarine until its overall density is greater than the surrounding water and the submarine begins to sink (negative buoyancy). A supply of compressed air is maintained aboard the submarine in air flasks for life support and for use with the ballast tanks. In addition, the submarine has movable sets of short “wings” called hydroplanes on the stern (back) that help to control the angle of the dive. The hydroplanes are angled so that water moves over the stern, which forces the stern upward; therefore, the submarine is angled downward."

This topic I found on the website got my attention because its the most common one of the submarine. The submarine always dives and surfaces if it didn't then it wouldn't be called the submarine. This is what makes a submarine work so I think I picked a good sub topic. (The submarine - How it works)

## Commentary #2

On the website sun dodgers their information was as good as the website how stuff works it explains the subtopic in ALOT of detail and the information stays with that topic. overall I think its a good cite. I think that the information goes good with the sub topic. Its worded really good to so its professional.

## Websites i used

http://www.easybib.com/

http://science.howstuffworks.com/transport/engines-equipment/submarine.htm

http://sundodgers.com/the-submariner/the-submarine-how-it-works/

-Brain, Marshall, and Ph.D. Craig Freudenrich. HowStuffWorks. HowStuffWorks.com, n.d. Web. 19 May 2015.

-"The Submarine - How It Works." Submarine Diary. N.p., 11 Dec. 2012. Web. 19 May 2015.