The amount of heat necessary for heating of a body depends on its weight, on change of its temperature and on the so-called specific heat of substance of which the body consists.
Instruction
1. The specific heat of substance is called the amount of heat necessary for heating or cooling of 1 kg of substance on 1 Calvin. That is in other words if for example the specific heat of water equals 4.2 kJ / (kg*k) - it means that to heat one kg of water by one degree, it is necessary to transfer to this kg of water 4.2 kJ of energy. The specific heat of substance is on a formula: C = Q/m(T_2-T_1) Unit of specific heat has dimension in the SI system – (J / kg*k).
2. The specific heat of a body is defined by practical consideration by means of a calorimeter and the thermometer. The simplest calorimeter consists of the polished metal glass put in other metal glass on traffic jams (for the purpose of thermal isolation) and filled with water or other liquid with the known specific heat. The body (firm, or liquid) heated to a certain temperature of t is lowered in a calorimeter in which temperature is taken. Let before lowering of the tested body liquid temperature was equal in a calorimeter to t_1 and after the water temperature (liquids) and the body lowered in it even out, it will become equal?.
3. Follows from the law of energy conservation that the warmth of Q given by a heated body is equal to the sum of warmth of Q_1 received by water and Q_2 received by a calorimeter: Q=Q_1+Q_2Q=cm (t-?), Q_1=c_1 m_1 (? - t_1), Q_2=c_2 m_2 (? - t_1) cm (t-?) = c_1 m_1 (? - t_1) + c_2 m_2 (? - t_1) here c_1 and m_1 - the specific heat and mass of water in a calorimeter, c_2 and m_2 - the specific heat and mass of material of a calorimeter. This equation expressing balance of thermal energy is called the equation of thermal balance. From it naydems= (Q_1+Q_2)/m (t-?) = (c_1 m_1 (? - t_1) + c_2 m_2 (? - t_1)) / m (t-?) = (c_1 m_1+c_2 m_2) (? - t_1) / m (t-?)