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Monday, July 27, 2009
Lever force to produce energy.
First of all I want to tell you about "lever" . Next post will be about producing Energy.
In physics, a lever is a rigid object that is used with an appropriate fulcrum or pivot point to multiply the mechanical force that can be applied to another object. This is also termed mechanical advantage, and is one example of the principle of moments. The principle of leverage can also be derived using Newton's laws of motion and modern statics.
1 Early studies
The earliest remaining writings regarding levers are provided by Archimedes ("Give me a place to stand, and I can move the Earth.", a remark of Archimedes quoted by Pappus of Alexandria) who formally stated the correct mathematical principle of levers.
2 Force and levers
The force applied (at end points of the lever) is proportional to the ratio of the length of the lever arm measured between the fulcrum and application point of the force applied at each end of the lever. Mathematically, this is expressed by M = Fd.
3 The three classes of levers
There are three classes of levers representing variations in the location of the fulcrum and the input and output forces.
3.1 First-class levers
Examples:
Seesaw (also known as a teeter-totter)
Crowbar
Pliers (double lever)
Scissors (double lever)
3.2 Second-class levers
Examples:
Wheelbarrow
Nutcracker (double lever)
3.3 Third-class levers
Examples:
Human arm
TongsTongs are gripping and lifting instruments, of which there are many forms adapted to their specific use. Some are merely large pincers or nippers, but the greatest number fall into three classes: the first, as in the common fire-tongs, used for picking up ( double lever )
4 See also
Engineering mechanicsEngineering mechanics is a branch of the physical sciences which looks to understand the actions and reactions of bodies at rest or in motion. Much of modern engineering mechanics is based on Isaac Newton's laws of motion while the modern practice of thei
Voting lever
Sunday, July 26, 2009
Solar Energy storage.
In this Article we will learn how to make storage energy produced by solar system.
Solar Two's thermal storage system generated electricity during cloudy weather and at night.
Solar energy is not available at night, and energy storage is an important issue because modern energy systems usually assume continuous availability of energy.
Thermal mass systems can store solar energy in the form of heat at domestically useful temperatures for daily or seasonal durations. Thermal storage systems generally use readily available materials with high specific heat capacities such as water, earth and stone. Well-designed systems can lower peak demand, shift time-of-use to off-peak hours and reduce overall heating and cooling requirements
Phase change materials such as paraffin wax and Glauber's salt are another thermal storage media. These materials are inexpensive, readily available, and can deliver domestically useful temperatures (approximately 64 °C). The "Dover House" (in Dover, Massachusetts) was the first to use a Glauber's salt heating system, in 1948.
Solar energy can be stored at high temperatures using molten salts. Salts are an effective storage medium because they are low-cost, have a high specific heat capacity and can deliver heat at temperatures compatible with conventional power systems. The Solar Two used this method of energy storage, allowing it to store 1.44 TJ in its 68 m³ storage tank with an annual storage efficiency of about 99%.
Off-grid PV systems have traditionally used rechargeable batteries to store excess electricity. With grid-tied systems, excess electricity can be sent to the transmission grid. Net metering programs give these systems a credit for the electricity they deliver to the grid. This credit offsets electricity provided from the grid when the system cannot meet demand, effectively using the grid as a storage mechanism.
Pumped-storage hydroelectricity stores energy in the form of water pumped when energy is available from a lower elevation reservoir to a higher elevation one. The energy is recovered when demand is high by releasing the water to run through a hydroelectric power generator.
Solar Energy
About half the incoming solar energy reaches the Earth's surface.
The Earth receives 174 petawatts (PW) of incoming solar ra
Solar Energy
This article is about all uses of solar energy. For generation of electricity using solar energy, see Solar power.
Solar energy is the radiant light and heat from the Sun that has been harnessed by humans since ancient times using a range of ever-evolving technologies. Solar radiation along with secondary solar resources such as wind and wave power, hydroelectricity and biomass account for most of the available renewable energy on Earth. Only a minuscule fraction of the available solar energy is used.
Solar power provides electrical generation by means of heat engines or photovoltaics. Once converted, its uses are limited only by human ingenuity. A partial list of solar applications includes space heating and cooling through solar architecture, potable water via distillation and disinfection, daylighting, hot water, thermal energy for cooking, and high temperature process heat for industrial purposes.
Solar technologies are broadly characterized as either passive solar or active solar depending on the way they capture, convert and distribute sunlight. Active solar techniques include the use of photovoltaic panels and solar thermal collectors (with electrical or mechanical equipment) to convert sunlight into useful outputs. Passive solar techniques include orienting a building to the Sun, selecting materials with favorable thermal mass or light dispersing properties, and designing spaces that naturally circulate air.
Energy from the Sun
About half the incoming solar energy reaches the Earth's surface.
The Earth receives 174 petawatts (PW) of incoming solar radiation (insulation) at the upper atmosphere.Approximately 30% is reflected back to space while the rest is absorbed by clouds, oceans and land masses. The spectrum of solar light at the Earth's surface is mostly spread across the visible and near-infrared ranges with a small part in the near-ultraviolet.
Earth's land surface, oceans and atmosphere absorb solar radiation, and this raises their temperature. Warm air containing evaporated water from the oceans rises, causing atmospheric circulation or convection. When the air reaches a high altitude, where the temperature is low, water vapor condenses into clouds, which rain onto the Earth's surface, completing the water cycle. The latent heat of water condensation amplifies convection, producing atmospheric phenomena such as wind, cyclones and anti-cyclones. Sunlight absorbed by the oceans and land masses keeps the surface at an average temperature of 14 °C By photosynthesis green plants convert solar energy into chemical energy, which produces food, wood and the biomass from which fossil fuels are derived.
and land masses is approximately 3,850,000 exajoules (EJ) per year. In 2002, this was more energy in one hour than the world used in one year. Photosynthesis captures approximately 3,000 EJ per year in biomass. The amount of solar energy reaching the surface of the planet is so vast that in one year it is about twice as much as will ever be obtained from all of the Earth's non-renewable resources of coal, oil, natural gas, and mined uranium combined.
From the table of resources it would appear that solar, wind or biomass would be sufficient to supply all of our energy needs, however, the increased use of biomass has had a negative effect on global warming and dramatically increased food prices by diverting forests and crops into biofuel production. As intermitten resources, solar and wind raise other issues.