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Water heating is a thermodynamic process using an energy source to heat water above its initial temperature. Typical domestic uses of hot water are for cooking, cleaning, bathing, and space heating. In industry, both hot water and water heated to steam have many uses. Domestically, water
heating means of making a building comfortably warm relative to a colder outside temperature. Old, primitive methods of heating a building or a room within it include the open fire, the fireplace, and the stove . In ancient Rome a heating system, called a hypocaust, warmed a building by passing hot gases from a furnace through enclosed passages under the floors and behind the walls before releasing them outside. The principal modern systems that are used to heat a building are classified as warm air, hot water, steam, or electricity. In the warm-air system air, heated in a furnace, rises through warm-air ducts and enters the rooms through outlets, while cooler air in the rooms passes into return ducts that lead back to the furnace. The air circulates through the system by convection, i.e., the tendency of a fluid such as air to rise when warm and sink when cool. In newer buildings the circulation is assisted by a fan. The hot-water system has a boiler for heating the water that is sent through connecting pipes to radiators and convectors, the latter devices being metal enclosures containing hot-water pipes surrounded by metal fins. The circulation is maintained by pumps or, in older buildings, by convection. In the steam-heating system, steam generated in a boiler is circulated by its own pressure (sometimes aided by a vacuum pump) through radiators. There are many kinds of electric heating systems. In one type current is sent through wires into electric resistors that are contained in convectors in rooms. The resistors convert the current into heat. In a radiant panel heating system a room is warmed by heat emitted from wall, floor, or ceiling panels. They are warmed by the circulation of warm air, hot water, or steam or by an electric current in resistors within or behind the panels. Experiments are being made to utilize solar energy for heating buildings. In many large buildings, such as theaters, public libraries, and municipal buildings, the heating, ventilating, and air-conditioning units are combined in one system. In district heating, heat is distributed from a heating plant to buildings in a section (usually commercial) of a city. Bibliography: See F. Porges, Handbook of Heating, Ventilating, and Air Conditioning (1982).
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Answers:1 st question answer is 4. 2 nd question answer is 3. 3 rd question answer is 4.
Answers:0.900 pint @ 36,400 cal / pint = 32,760 calories 32,760 calories @ 4.184 joules / cal = 137,068 Joules 137,068 joules @ 1 kJ / 1000 Joules = your answer: 137 kJ
Answers:For the first two, use the equation q=mc(T2-T1). n this equation, q is the heat absorbed or lost, m is the mass of the water sample, c is the specific heat of water (4.184 J/gC) and T2 and T1 are the final and initial temperatures of the water. In both problems, you can just plug in what you have and solve for the one you don't have. In the last one, the answer is (3) equal volumes and the same number of molecules.
Answers:1 calorie is by definition the amount of energy required to increase the temperature of 1 gram of water by 1 degree C. You have 5 grams, and you need to increase its temperature by 23 degree, so 5*23=115 calories (a calorie is 4.184 joules, so if you prefer the answer in that unit, then it is 481.16 joules) Boiling water is however a two step process. First you have to heat the water to 100 C, and then you have to add more energy to turn the water at 100 C into steam at 100 C. This heat of vaporisation is equal to 2270 joules/g. So, 236.5 g with a variation of 73 degree: 17264.5 calorie or 72234.7 Joules. 236.5 g with a vaporisation energy of 2270 g: 536855 joules. Total: 609089.7 joules.