Heat
This document was uploaded by user and they confirmed that they have the permission to share it. If you are author or own the copyright of this book, please report to us by using this DMCA report form. Report DMCA
Overview
Download & View Heat as PDF for free.
More details
- Words: 369
- Pages: 2
HEAT IS: • • • • •
A form of energy. Flows from a religion of high temperature to a region of low temperature. Can cause things become hot. Can travel through solid, liquid, gas and even vacuum. Measured in joules.
Heat can cause a body to expand, experience a rise in temperature or undergo a change of state.
SOURCES OF HEAT: • • • •
The sun is a source of heat. The flame of match gives out heat. Heat is given out when an electric current flows through a wire. Heat ca be produced by rubbing our hand together.
In physics, heat, symbolized by Q, is energy transferred from one body or system to another due to a difference in temperature.[1][2] In thermodynamics, the quantity TdS is used as a representative measure of the (inexact) heat differential δQ, which is the absolute temperature of an object multiplied by the differential quantity of a system's entropy measured at the boundary of the object. Heat can flow spontaneously from an object with a high temperature to an object with a lower temperature. The transfer of heat from one object to another object with an equal or higher temperature can happen only with the aid of a heat pump. High temperature bodies, which often result in high rates of
heat transfer, can be created by chemical reactions (such as burning), nuclear reactions (such as fusion taking place inside the Sun), electromagnetic dissipation (as in electric stoves), or mechanical dissipation (such as friction). Heat can be transferred between objects by radiation, conduction and convection. Temperature is used as a measure of the internal energy or enthalpy, that is the level of elementary motion giving rise to heat transfer. Heat can only be transferred between objects, or areas within an object, with different temperatures (as given by the zeroth law of thermodynamics), and then, in the absence of work, only in the direction of the colder body (as per the second law of thermodynamics). The temperature and phase of a substance subject to heat transfer are determined by latent heat and heat capacity. A related term is thermal energy, loosely defined as the energy of a body that increases with its temperature.
A form of energy. Flows from a religion of high temperature to a region of low temperature. Can cause things become hot. Can travel through solid, liquid, gas and even vacuum. Measured in joules.
Heat can cause a body to expand, experience a rise in temperature or undergo a change of state.
SOURCES OF HEAT: • • • •
The sun is a source of heat. The flame of match gives out heat. Heat is given out when an electric current flows through a wire. Heat ca be produced by rubbing our hand together.
In physics, heat, symbolized by Q, is energy transferred from one body or system to another due to a difference in temperature.[1][2] In thermodynamics, the quantity TdS is used as a representative measure of the (inexact) heat differential δQ, which is the absolute temperature of an object multiplied by the differential quantity of a system's entropy measured at the boundary of the object. Heat can flow spontaneously from an object with a high temperature to an object with a lower temperature. The transfer of heat from one object to another object with an equal or higher temperature can happen only with the aid of a heat pump. High temperature bodies, which often result in high rates of
heat transfer, can be created by chemical reactions (such as burning), nuclear reactions (such as fusion taking place inside the Sun), electromagnetic dissipation (as in electric stoves), or mechanical dissipation (such as friction). Heat can be transferred between objects by radiation, conduction and convection. Temperature is used as a measure of the internal energy or enthalpy, that is the level of elementary motion giving rise to heat transfer. Heat can only be transferred between objects, or areas within an object, with different temperatures (as given by the zeroth law of thermodynamics), and then, in the absence of work, only in the direction of the colder body (as per the second law of thermodynamics). The temperature and phase of a substance subject to heat transfer are determined by latent heat and heat capacity. A related term is thermal energy, loosely defined as the energy of a body that increases with its temperature.
