Submarines

Wood was used to make the first submarine

Are you thinking about implementing groups in your classroom? When it comes to assigning students to work in groups, it takes a great deal of time to put group work into action in the classroom. There are three strategies that can help individuals manage groups in the classroom. These strategies include the following: Planning Groups. Individuals may consider this as a time-consuming task, but it is very necessary to take the time out to plan for groups. When planning for groups, individuals need to think about whether the students know each other and how well will they work together in a group setting. For example, groups may be assigned based upon a previous test grade on a specific topic or even common interests related to a specific topic. Therefore, individuals need to ensure that they identify the criteria necessary for assigning each group so that it will be on file for future reference, just in case administrators ask for it. Not to mention, this type of information will come in handy when it comes time to change group assignments to ensure that students have experience working in diverse groups. Assigning Each Group Member a Task: Each group member should be focused on contributing to the group. By assigning each group member a task, individuals are able to hold each group member accountable and reduce any behaviors that may arise in the group. For instance, individuals who are creating groups can assign the following tasks: (a) Collect Materials; (b) Lead the Group; (c) Write for the Group; and (d) Keep time for the Group. Each of these tasks may seem simple, but they definitely do keep groups on task. Interacting with Each Group. This may seem like the time to grade papers or even check email while students are working in groups. Well, it’s not…this time should be used to interact with each group. This is how individuals will be able to ensure that students stay on task, but most importantly, they will be able to help the struggling group members or even model how to work in a group setting for students. These are three strategies that can be used to help manage groups in the classroom. The bottom line is that group work takes a great deal of time and effort and students should be strategically assigned to groups to ensure that each learner has the best group learning experience possible for a specific lesson.

No - USS Alligator, the U.S. Navy's first submarine, was cut loose during bad weather while being towed off of Cape Hatteras. It's not known if she sank immediately (unlikely) or drifted some time before sinking. As such, and due to the extreme weather the Hatteras area normally sees during hurricane season, the only way she'll ever be found (if ever) is by accident.

The weight of a submarine varies significantly based on its type and purpose. A small research submarine might weigh around 100 tons, while larger military submarines, such as nuclear-powered ones, can weigh over 10,000 tons when submerged. The heaviest submarines, like the Russian Typhoon class, can exceed 24,000 tons. Overall, submarines are designed to be heavy enough to submerge and navigate underwater effectively.

The Turtle (also known as the American Turtle) was the first submarine to be used in combat. It was built in 1775 and used on September 6, 1776 in an unsuccessful attack against the HMS Eagle. It was invented by David Bushnell.

WWII subs burned diesel fuel. Nuclear-powered submarines use uranium in their nuclear reactors. They also have diesel-powered generators, which use diesel fuel.

One of the first military submersibles - called the "Turtle" and invented during the American Civil War - was powered by the single occupant's leg & arm muscles, operating various "propellers" on the exterior of his barrel-shaped device. This was not terribly efficient. Subsequently, early attempts were made to power submersibles with steam engines, underwater oars and more hand-cranking.

None of these methods were particularly successful.

Eventually a chap called John Holland designed perhaps the first true submarine, powered by batteries whilst submerged and by an internal combustion engine whilst on the surface. The i/c engine also charged the main batteries whilst running. This design was improved and modified until German engineers built the Type VII "Unterseeboot" or U-Boat of WW2 fame, which culminated in the Type XXI Diesel-Electric layout used by most D/E boats today.

But that's not all. Modern submarines - even the "Schnorkel"-equipped Diesel electric designs in use today - have several major weaknesses. They have to come up to let their crews breathe fresh air, they need fresh water for drinking and their batteries - and those batteries have to be recharged whilst the submarine is at periscope depth - a particularly risky place to be in a submarine.

So, if you fit a small nuclear reactor into a well-shielded area of a new submarine design, let the heat from that reaction superheat some water, you can generate steam to run a turbine - for propulsion and for electrical power. With this amount of power available, you can keep the internal air clean by splitting seawater into Oxygen and Hydrogen, then scrubbing the exhaled CO2 breathed out by the crew. You can make fresh water from seawater and - basically - a modern nuclear boat doesn't have to surface for months at a time. In fact, the main limit to the time one of these ultimate arbiters of peace stays submerged is the amount of food it carries for its crew.