Q4 of 16 Page 35

Answer the following :

Distinguish between heat and temperature.

The temperature of any object is the average of the kinetic energies of all the molecules inside the object. It is a measure of the thermal or heat energy present in a substance. All the molecules in an object may not have the same energy so the average of all the energies of molecules will give the temperature of the object.


Heat, on the other hand, is the total energy of the motion of molecules in a substance. The movement of molecules is random and every molecule has a different energy. The sum total of the energies of all the molecules is the heat.


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2

Fill in the blanks with suitable words:

1. The degree of hotness of a body is called_______ (heat/ temperature)


2. Temperature is expressed in_______(degree centigrade/joule)


3. A substance changes from liquid to gas at constant temperature.


It is called _______(condensation/boiling point)


4. The temperature of boiling water in the Celsius scale of temperature is ________°C (100/373/212/32)


5. The SI unit of heat is _________(Joule/Celsius)

 3

State whether the following statements are true or false:

1. Liquids expand on heating.


2. The unit of heat and temperature are the same.


3. A bimetallic strip is used in fans.

 4

Answer the following :

Mention three different effects produced by heat.

 4

Answer the following :

Give one example to illustrate that heat can be generated from the energy of motion.