Mechanical Engineering

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Modern U.S. submarines are built by what is known as "Modular" construction. In the early days of Nuclear boats, construction was like any Navy vessel - from the keel up. However, with the advent of the Trident FBM submarines modular construction was developed, and found to be much more advantageous.

Essentially, each major compartment is built individually in separate sections. When completed to a certain point, the sections are brought together (they're constructed on a rail system) and then welded together. All systems are connected as the compartments come together. Seeing each section being built at the Shipyard is a real sight to behold, but not as much as seeing a Trident Submarine on the rails next to an LA class boat. What you actually see above water is only about 1/5 of the boat's actual size - most of it is underwater.

This construction method is much faster than the old way, and is just as strong. Use the link below to see an image of a module of a UK Astute class submarine on its way from a builder to the yards.

a speed multiplier is an object which moves at high speed and multiplies that to create more speed with an object it is trying to move. an example is hitting a tennis ball with a tennis raquet - you swing your arm/hand at a short distance at high speed and great effort so travels a great distance at an even higher speed. the distance the ball moves is large so the force by your arm/hand is small. hope this helps! :)
speed multiplier- machine that requires a small movement of an effort to produce a large movement of a load, such as a third class lever.

source: Pearson Science S.B

As a safety disclaimer, parental guidance should be sought by minors before initiatiating any kind of electric arc or using electricity or electrical devices. It is also advisable for everyone to use safety eyewear, such as goggles, before using electricity in the manners described, below and elsewhere, and to avoid areas which contain flammable liquids or gases.

One method of making an electric arc is to connect wires to each side of a low-voltage electric battery - - such as a standard, 1.5 volt, household, battery (i.e., AA, AAA, C, D, etc) - - then touch the unconnected ends together (best seen in a darkened area).

Another method is to use a Tesla coil (created by Nikolai Tesla), which creates long arcs, which have been referred to as "artificial lightning", at least in appearance. Tesla coils are used in school science labs and in science museums. Plasma bulbs produce the same effect, though to a far lesser degree than a Tesla coil, and are available in some retail stores.

Another method is to walk on a fabric carpet, and then touch a metal object, such as a stair rail or oven door. This is a form of "static" electricity, and is the most common way most people produce electric arcs, though, usually, not on purpose. Again, a darkened area makes for the best viewing.

Another View: (Different contributor)

An electrical arc can be created under many circumstances and by several methods. An arc is most commonly created when the potential difference (Voltage) is increased to the point that air has the ability to conduct electricity. Typically this is only possible when the voltage exceeds the KV range (>1000 Volts). And is extremely dangerous depending on the amount of current available supplying the voltage.

An electrical arc is also created when a flowing current is interrupted (A light switch or contactor opening). In this event, the arc will allow the flow of electrons through free air only until the distance between the two contact points prevents the free air to conduct electricity. The effect or duration of the arc can be increased by the creation of Ozone gas that is generated from the heat of the electricity heating the air. The presence of more current will increase the amount of heat, and also the amount of Ozone, so the arc will be larger.

In common practice, the use of a high voltage furnace ignitor, neon sign transformer, and Tesla Coil (All conisdered transformers) can by used to generate high voltages (More than 5Kv or 5000 volts). Only people with training/experience with high voltages should ever attempt to generate electrical arcs, and with close supervision and safety protocols.

Another source of artificially generating an electrical arc is the use of a Van De Graff Generator. Where a mechanical source is used to turn a non-conductive belt to deposit electrons on a stationary screen. Thus the arc is created by 'static electricity' (The same effect as rubbing your feet across a carpet, then touching a door handle) The electrons accumulate until a sufficient charge is built up to allow for discharge across free air to a ground reference. Typical charges are in excess of 10Kv (10,000 volts) and while they are low current, should still be considered dangerous.

Modern 'Stun Guns' use a principle of combined capacitance & artificial frequency generation to turn relatively low DC (Direct Current) voltages into high frequency, high voltage (albeit low current) electrical arcs...