Thermodynamics

A:

Metals conduct heat well for two reasons: metal ions pack very closely together in their molecular lattice, and electrons drifting through the metal carry kinetic energy around the lattice. The result is a quick elevation in particle motion that is expressed through heat energy. This conductivity is one reason why one rarely sees metal playground equipment anymore — although the slides go a lot faster than plastic ones, sitting on a slide on a hot summer afternoon is often quite painful.

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  • Why does heat rise?

    Q: Why does heat rise?

    A: Hot air rises because when a substance is hot, its molecules are farther apart, which makes the hot air less dense and, therefore, lighter than cooler air. Air is generally warmer nearer the surface of the Earth because of the sun's radiating heat. When hot air rises, it starts to get cooler and eventually it sinks back down to the surface.
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  • Which metal conducts heat the fastest?

    Q: Which metal conducts heat the fastest?

    A: Silver is the metal that conducts heat the fastest. The thermal conductivity of silver is 420 W/ (m• K) or watts per meter degrees of Kelvin. Thermal conductivity measures the ability of heat or thermal energy to move through materials.
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  • What is the hottest part of the day?

    Q: What is the hottest part of the day?

    A: According to the National Satellite and Information Service, the hottest time of the day is generally around midafternoon. The exact time of the day that it is the hottest depends on where a person lives and what time of the year it is.
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  • What is an example of convection?

    Q: What is an example of convection?

    A: Convection occurs when a cold pot of water is placed on a stove burner that transfers heat to the bottom of the pan. As the water in the pan warms, it begins to bubble on the surface. Generally, convection transfers heat from a warm area to a cooler one.
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  • Why are metals such good conductors of heat?

    Q: Why are metals such good conductors of heat?

    A: Metals conduct heat well for two reasons: metal ions pack very closely together in their molecular lattice, and electrons drifting through the metal carry kinetic energy around the lattice. The result is a quick elevation in particle motion that is expressed through heat energy. This conductivity is one reason why one rarely sees metal playground equipment anymore — although the slides go a lot faster than plastic ones, sitting on a slide on a hot summer afternoon is often quite painful.
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  • How does an oil heater work?

    Q: How does an oil heater work?

    A: According to About.com expert Timothy Thiele, oil heaters are electric appliances that warm the surrounding air by passing hot oil through a series of metal tubes. Oil is the ideal filling for space heaters because it heats quickly and gets extremely hot without boiling. As the heater runs, the hot oil heats its metal tubing, which has poor heat retention and quickly releases the heat into the air.
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  • Which freezes faster: freshwater or saltwater?

    Q: Which freezes faster: freshwater or saltwater?

    A: Freshwater freezes faster that saltwater, according to the National Oceanic and Atmospheric Administration. Freshwater freezes at 32 F, while saltwater freezes at a slightly lower temperature, 28.4 F.
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  • Why is boiling a cooling process?

    Q: Why is boiling a cooling process?

    A: Boiling can be considered as a cooling process because as a liquid reaches its critical temperature, heat escapes through rapid evaporation. Essentially, boiling happens when liquids turn into gases, forcing excess heat out of the liquid.
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  • Why do flames go upwards?

    Q: Why do flames go upwards?

    A: Visible flames are hot gases emitting light, which naturally rises because it is hotter (and therefore less dense) than the air around it. These hot gases are byproducts of the chemical reaction of combustion, or burning.
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  • Can you tell what temperature a fire is by its color?

    Q: Can you tell what temperature a fire is by its color?

    A: The temperature of a flame from a known material can be estimated based on the flame's color. However, flame color is also affected by the material being burnt and differs based on its chemical properties in addition to its temperature.
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  • How are temperature and thermal energy different?

    Q: How are temperature and thermal energy different?

    A: The difference between temperature and thermal energy is that temperature measures the average kinetic speed of molecules and thermal energy is the total kinetic energy of all particles in a given substance. In other words, temperature measures the average speed of movement, and thermal energy measures the mass of a substance. Both temperature and thermal energy are made by the movement of particles.
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  • How does a fuel pump work?

    Q: How does a fuel pump work?

    A: A fuel pump pulls gasoline from the tank, guiding it along a pipe to the carburetor. Some fuel pumps are electric, mounted near or in the fuel tank, while others operate mechanically in concert with the engine. Either way, the fuel pump is what gets the gasoline where it needs to go.
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  • What materials are good conductors of heat?

    Q: What materials are good conductors of heat?

    A: Many metals, like silver, copper, gold and aluminum, are good thermal conductors. Thermal conductors are materials that heat passes through easily. Conduction, or the transfer of heat, can take place within a single material or between two objects.
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  • At what temperature does duct tape melt?

    Q: At what temperature does duct tape melt?

    A: Industry safety standards require duct tape to be nonflammable and safe to use in temperatures up to 200 degrees Fahrenheit. Adhesive endurance is reduced in temperatures over 180 degrees Fahrenheit.
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  • What is a candle flame made up of?

    Q: What is a candle flame made up of?

    A: While a flame is the gaseous portion of a fire, a candle flame contains millions of diamond nanoparticles. Approximately 1.5 million diamond nanoparticles are created every second before converting into carbon dioxide. All four forms of carbon are present within a candle flame: elemental carbon, graphite, white carbon and diamond.
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  • How hot is an acetylene torch?

    Q: How hot is an acetylene torch?

    A: An Acetylene torch flame reaches a temperature of 3,500 degree C, or 6,330 degrees F. This high temperature is reached when oxygen and acetylene are combined and burned together after being released from two separate tanks.
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  • Q: What causes thermal energy to change?

    A: Temperature causes changes in the amounts of thermal energy held by a substance or system. The higher the temperature, the higher the amount of thermal energy held.
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  • What is a poor conductor of heat?

    Q: What is a poor conductor of heat?

    A: A poor conductor of heat is any material that can not transfer heat. Poor conductors have a low density thus the particles in a given volume of the material are not enough to collide and transfer heat. Examples of poor heat conductors include air, wood, paper, cloth and water.
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  • Q: How does energy flow?

    A: According to the second law of thermodynamics, energy flows in the direction of increasing randomness. This randomness is quantified as entropy, a universal value that always increases due to the inescapable dissipation of energy.
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  • Q: How is fire made?

    A: According to Wikipedia, fire is a rapid, exothermic oxidation of a material, also known as combustion. For combustion to occur, energy in the form of heat, combustible material and an oxidizing agent like fluorine or oxygen must be present, according to Reader's Digest.
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  • Q: Why do ice cubes float to the top of a glass of water?

    A: Ice floats in water because, unlike most substances, the solid phase of water is less dense than its liquid phase. When water freezes, it expands slightly, and the resulting change in density is enough to allow ice cubes to float in a glass of water.
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