heat

(noun)

energy transferred from one body to another by thermal interactions

Related Terms

Examples of heat in the following topics:

  • Specific Heat

    • The specific heat is an intensive property that describes how much heat must be added to a particular substance to raise its temperature.
    • The heat capacity is an extensive property that describes how much heat energy it takes to raise the temperature of a given system.
    • This quantity is known as the specific heat capacity (or simply, the specific heat), which is the heat capacity per unit mass of a material .
    • The specific heat is the amount of heat necessary to change the temperature of 1.00 kg of mass by 1.00ºC.
    • Note that the total heat capacity C is simply the product of the specific heat capacity c and the mass of the substance m, i.e.,

  • Heat Pumps and Refrigerators

    • A heat pump is a device that transfers heat energy from a heat source to a heat sink against a temperature gradient.
    • Heat pumps, air conditioners, and refrigerators utilize heat transfer from cold to hot.
    • Actually, a heat pump can be used both to heat and cool a space.
    • As with heat pumps, work input is required for heat transfer from cold to hot.
    • What is considered the benefit in a heat pump is considered waste heat in a refrigerator.

  • Overview of Heat

    • Energy can exist in many forms and heat is one of the most intriguing.
    • This module defines and explores heat transfer, its effects, and the methods by which heat is transferred.
    • Maxwell outlined four stipulations for the definition of heat:
    • After defining and quantifying heat transfer and its effects on physical systems, we will discuss the methods by which heat is transferred.
    • So many processes involve heat transfer, so that it is hard to imagine a situation where no heat transfer occurs.

  • Heat Engines

    • In thermodynamics, a heat engine is a system that performs the conversion of heat or thermal energy to mechanical work.
    • In thermodynamics, a heat engine is a system that performs the conversion of heat or thermal energy to mechanical work .
    • We define the efficiency of a heat engine (Eff) to be its net work output W divided by heat transfer to the engine Qh:
    • (b) A heat engine, represented here by a circle, uses part of the heat transfer to do work.
    • Qh is the heat transfer out of the hot reservoir, W is the work output, and Qc is the heat transfer into the cold reservoir.

  • Heat as Energy Transfer

    • Heat is the spontaneous transfer of energy due to a temperature difference.
    • This observation leads to the following definition of heat: Heat is the spontaneous transfer of energy due to a temperature difference .
    • Heat is often confused with temperature.
    • Heat is a form of energy, whereas temperature is not.
    • We use the phrase "heat transfer" to emphasize its nature.

  • Global Warming Revisited

    • As an engine operates, heat flows from a heat tank of greater temperature to a heat sink of lesser temperature.
    • In between these states, the heat flow is turned into useful energy with the help of heat engines.
    • Department of Energy, 70% to 72% of heat produced by burning fuel is heat lost by the engine.
    • The excess heat lost by the engine is then released into the heat sink, which in the case of many modern engines would be the Earth's atmosphere.
    • As more heat is dumped into the environment, Earth's atmospheric (or heat sink) temperature will increase.

  • Work

    • For closed systems, energy changes in a system other than as work transfer are as heat.
    • Heat transfer, a less organized process, is driven by temperature differences.
    • Nevertheless, heat and work can produce identical results.
    • Both heat and work can cause a temperature increase.
    • Internal energy is a form of energy completely different from either heat or work.

  • Solving Problems with Calorimetry

    • To do so, the heat is exchanged with a calibrated object (calorimeter).
    • The change in temperature of the measuring part of the calorimeter is converted into the amount of heat (since the previous calibration was used to establish its heat capacity).
    • The temperature change, along with the specific heat and mass of the solution, can then be used to calculate the amount of heat involved in either case.
    • Use these data to determine the specific heat of the metal.
    • Assuming perfect heat transfer, the heat given off by metal is the negative of the heat taken in by water, or:

  • Heat Capacity

    • The heat capacity measures the amount of heat necessary to raise the temperature of an object or system by one degree Celsius.
    • An object's heat capacity (symbol C) is defined as the ratio of the amount of heat energy transferred to an object to the resulting increase in temperature of the object .
    • For example, if it takes 1,000 J to heat a block of iron, it would take 2,000 J to heat a second block of iron with twice the mass as the first.
    • The heat capacity of most systems is not a constant.
    • This defines the heat capacity at constant volume, CV.

  • Latent Heat

    • The latent heat is the energy associated with a phase change of a substance.
    • Previously, we have discussed temperature change due to heat transfer.
    • where the latent heat of fusion, Lf, and latent heat of vaporization, Lv, are material constants that are determined experimentally.
    • Lf and Lv are collectively called latent heat coefficients.
    • Heat from the air transfers to the ice causing it to melt.