Question

Distinguish between heat and temperature

ICSE Class 9 Physics Chapter Heat and Energy

Answer 1

There is a fundamental difference between temperature and heat. Heat is the amount of energy in a system. The SI units for heat are Joules. A Joule is a Newton times a meter. A Newton is a kilogram-meter per second squared. Heat is transferred through radiation, conduction and convection. The amount that molecules are vibrating, rotating or moving is a direct function of the heat content. Energy is transported by conduction as molecules vibrate, rotate and/or collide into each other. Heat is moved along similar to dominos knocking down their neighbors in a chain reaction. An increase of electromagnetic radiation into a system causes the molecules to vibrate, rotate and/or move faster. With convection, higher energy molecules are mixed with lower energy molecules. When higher energy molecules are mixed with lower energy molecules the molecular motion will come into equilibrium over time. The faster moving molecules will slow down and the slow moving molecules will speed up. 

Temperature is the MEASURE of the AVERAGE molecular motions in a system and simply has units of (degrees F, degrees C, or K). Notice that one primary difference between heat and temperature is that heat has units of Joules and temperature has units of (degrees F, degrees C, or K). Another primary difference is that energy can be transported without the temperature of a substance changing (e.g. latent heat, ice water remains at the freezing point even as energy is brought into the ice water to melt more ice). But, as a general statement (ignoring latent heat), as heat energy increases, the temperature will increase. If molecules increase in vibration, rotation or forward motion and pass that energy to neighboring molecules, the measured temperature of the system will increase.

Answer 2

Heat

In physic science, heat refers to the energy that is transfer by way of work or other matter. Generally, heat flows from a hotter object to a colder one. This transfer result in a net increase in entropy. This process can be direct, as in conduction and radiation while in case of indirect as in convective circulation. Generally heat refers to the process of transfer between two systems, the systems of interest and its surroundings considered as a system, not a state or property of a single system. The amount of energy transferred by way of heat is expressed in a SI unit of joule (J). Heat can be measured by calorimetry or by other scaling techniques that are based on the first law of thermodynamics. J. R. Partington – a British chemist – describes conduction as: “If a hot body is brought in conducting contact with a cold body, the temperature of the hot body falls and that of the cold body rises, and it is said that a quantity of heat passed form the hot body to the cold body.”

Temperature

In physics, temperature refers to the measurement of hotness or coldness in an object by using a thermometer. Various scales and unites are used to measure temperature like the most common being used is Celsius (denoted by °C and also known as centigrade), Fahrenheit (denoted by °F) and in science by the name of Kelvin (denoted by K). Temperature is the measure of average heat or thermal energy of the molecules in a substance. For example, when we say an object temperature is 100 degrees, then it doesn’t mean that every single molecules has that exact thermal energy. In every substance, molecules are moving with a different range of energies, and are interacting with each other that changes their energies. Temperature is equally important in all fields of sciences such as biology, atmospheric science, physics, chemistry, geology, medicine, in short, in most aspects of daily life.

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