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By allowing water to flow in pipes around the heated parts of a machine, heat energy from such part is removed. Water in pipes extracts more heat from surrounding without much rise in its temperature because of its large specific heat capacity. So, Water is used as an effective coolant.

Reasons used : 1kg of ice on meting absorbs 336000J of heat energy and 1kg of water to freeze will absorb 336000J of heat energy.

When ice start meting heat is absorbed from the atmosphere (336000J for every 1kg of ice) and temp, falls in the surrounding and it becomes very cold.

Reasons used : 1kg of ice on meting absorbs 336000J of heat energy and 1kg of water to freeze will absorb 336000J of heat energy.

 Sp. Latent heat of ice is 336000J for every 1kg ice. Hence to change ice at 0°C to water at 0°C, it will extract 336000J of heat from the hot engine and will cool the engine for longer time. 

 In cold countries water is used as heat reservoir for wine and juice bottle to avoid freezing. Due to high specific heat capacity imports a large amount of heat before reaching to the freezing temp. Hence bottles kept in water remains warm and do not freeze. 

(1) Radiator in car.

(2) To avoid freezing of wine and juice bottles.

The S.I. unit of specific heat capacity is Jk^-1.

A calorimeter is a cylindrical vessel which is used to measure the amount of heat gained or lost by a body when it is mixed with other body.

It is made up of thin copper sheet because:

(i) Copper is a good conductor of heat, so the vessel soon acquires the temperature of its contents.

(ii)Copper has low specific heat capacity so the heat capacity of calorimeter is low and the amount of heat energy taken by the calorimeter from its contents to acquire the temperature of its contents is negligible.

By making the base of a cooking pan thick, its thermal capacity becomes large and it imparts sufficient heat energy at a low temperature to the food for its proper cooking. Further it keeps the food warm for a long time, after cooking.

The principle of method of mixture:

Heat energy lost by the hot body = Heat energy gained by the cold body.

This principle is based on law of conservation of energy.

The specific heat capacity of water is very high. It is about five times as high as that of sand.

Hence the heat energy required for the same rise in temperature by a certain mass of water will be nearly five times than that required by the same mass of sand. Similarly, a certain mass of water will give out nearly five times more heat energy than that given by sand of the same mass for the same fall in temperature. As such, sand gets heated or cooled more rapidly as compared to water under the similar conditions. Thus a large difference in temperature is developed between the land and the sea due to which land and sea breezes are formed. These breezes make the climate near the sea shore moderate.The specific heat capacity of water is very high. It is about five times as high as that of sand. Hence the heat energy required for the same rise in temperature by a certain mass of water will be nearly five times than that required by the same mass of sand. Similarly, a certain mass of water will give out nearly five times more heat energy than that given by sand of the same mass for the same fall in temperature. As such, sand gets heated or cooled more rapidly as compared to water under the similar conditions. Thus a large difference in temperature is developed between the land and the sea due to which land and sea breezes are formed. These breezes make the climate near the sea shore moderate.

The principle of calorimetry is based on the law of conservation of energy.

(c) total internal energy of the two bodies

The other name given to the principle of mixture is the principle of calorimetry. 

In the absence of water, if on a cold winter night the atmospheric temperature falls below 0^oC, the water in the fine capillaries of plant will freeze, so the veins will burst due to the increase in the volume of water on freezing. As a result, plants will die and the crop will be destroyed. In order to save the crop on such cold nights, farmers fill their fields with water because water has high specific heat capacity, so it does not allow the temperature in the surrounding area of plants to fall up to 0^oC.

(d) is dimensionless.

 (i) Heat capacity is the amount of heat required to raise the temperature of a body by 1°C or 1K. Thus, 60JK^-1 of energy is required to raise the temperature of the given body by 1K. 

(ii) Specific heat capacity is the amount of heat energy required to raise the temperature of unit mass of a substance through 1°C or IK. Thus, 130JKg^-1K^-1 of heat energy required to raise the temperature of unit mass of lead through 1K. 

(i) The heat capacity of a body is 50JK^-1 means to increase the temperature of this body by 1K we have to supply 50 joules of energy. 

(ii) The specific heat capacity of copper is 0.4Jg^-1K^-1 means to increase the temperature of one gram of copper by 1K we have to supply 0.4 joules of energy.

The principle of method of mixture says that the heat lost by a hot body is equal to the heat gained by a cold body. 

Heat absorbed by a body is directly proportional to : 1. its mass 

2. Rise in temperature 

3. Specific heat capacity

The correct answer is (c) (d)

(c) the mass of the body 

(d) the material of the body.

The expression for the heat energy Q

Q= mc Δ t (in joule)

The quantity of heat energy absorbed by a body depends on three factors :

(i)Mass of the body - The amount of heat energy required is directly proportional to the mass of the substance.

(ii)Nature of material of the body - The amount of heat energy required depends on the nature on the substance and it is expressed in terms of its specific heat capacity c.

(iii)Rise in temperature of the body - The amount of heat energy required is directly proportional to the rise in temperature.