HEAT AND THERMODYNAMICS Classical thermodynamics…. is the only physical theory of universal content which I am convinced… will never be overthrown. – Albert Einstein is a branch of physics which explains the phenomena of temperature, heat etc. The concepts presented in this chapter will help us to understand the terms ‘hot’ and ‘cold’ and also differentiate heat from temperature.
In thermodynamics, heat and temperature are two different but closely related parameters. . . Meaning of heat When an object at higher temperature is placed in contact with another object at lower temperature, there will be a spontaneous flow of energy from the object - - - - Unit Heat and thermodynamics b.
When heated, a cup of coffee receives heat from the stove. Once the coffee is taken from the stove, the cup of coffee has more internal energy than before. ‘Heat’ is the energy in transit and which flows from an object at higher temperature to an object at lower temperature. Heat is not a quantity.
So the statement ‘A hot cup of coffee has more heat’ is wrong, instead ‘coffee is hot’ will be appropriate. . . Meaning of work When you rub your hands against each other the temperature of the hands increases.
You have done some work on your hands by rubbing. The temperature of the hands increases due to this work. Now if you place your hands on the chin, the temperature of the chin increases. This is because the hands are at higher temperature than the chin.
In the above example, the temperature of hands is increased due to work and temperature of the chin is increased due to heat transfer from the hands to the chin. It is shown in the Figure . By doing work on the system, the temperature in the system will increase and sometimes may not. Like heat, work is also at higher temperature to the one at lower temperature.
This energy is called heat. This process of energy transfer from higher temperature object to lower temperature object is called heating. Due to flow of