Energy transfer
The flow of energy from one region to another region is referred to as energy transfer. Since energy is quantitative; it must be transferred to a body or a material to work or to heat the system.
Molar Specific Heat
Heat capacity is the amount of heat energy absorbed or released by a chemical substance per the change in temperature of that substance. The change in heat is also called enthalpy. The SI unit of heat capacity is Joules per Kelvin, which is (J K-1)
Thermal Properties of Matter
Thermal energy is described as one of the form of heat energy which flows from one body of higher temperature to the other with the lower temperature when these two bodies are placed in contact to each other. Heat is described as the form of energy which is transferred between the two systems or in between the systems and their surrounding by the virtue of difference in temperature. Calorimetry is that branch of science which helps in measuring the changes which are taking place in the heat energy of a given body.
Hot or cold objects are observed to cool down or warm up, respectively, to reach
the temperature of the environment. If the temperature difference ∆T between the object and its neighborhood
(∆T = Tobjeto - Tvizinha¸ca) is not large, the cooling or heating rate of the object will be
approximately proportional to the temperature difference, i.e,
d ∆T/dt = -A (∆T) ,
where A is a positive constant. This is Newton's law of cooling.
a. Why is there a minus sign in the equation?
b. What factors does A depend on and what are its dimensions?
c. If at instant t = 0 the temperature difference is ∆T0, show that at a later instant t the temperature will equal
∆T = ∆T0and^-At
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