PHYSICS [2 Mark Question Answer]

Water freezes at sub-zero temperature and in doing so expands (anomalous behaviour of water). So exposed water pipes during severe winter are lagged with straw so as to provide sufficient space for expansion of freezing water.

Water freezes at sub-zero temperature and in doing so expands (anomalous behaviour of water).
So taps are left dripping in sub-zero temperature during winter so as to provide sufficient space for expansion of freezing water.

In severe winter, water pipe lines often burst because water freeze at sub-zero temperature and in doing so expands. Since there is no space within the pipes for expanding ice, it exerts very large pressure and bursts open the steel pipes.

Heat :
1. Heat is a form of energy which flows.
2 Its S.I. unit is joule or J.
3. It flows from hot body to cold body.
Temperature:
1. Temperature is a quantity which tells the thermal atate of body.
2 Ita S.I. unit is Kelvin or K.
3. It determines the direction of flow of heat when two bodies at different temp, are placed in contact.

(a) Temperature: The degree of hotness coldness of a body is called temperature. OR Temperature is the effect of heat energy which determines the thermal atate of a body.
(b) Temperature: On the basis of kinetic theory of matter, temperature is the average kinetic energy of all the molecules of a substance.

(a) Heat energy: It is a form of energy which causes in us the sensation of hotnesa or coldness.
(b) Heat energy: On the basis of kinetic theory of matter, heat energy is defined as the aum total of kinetic and potential energiea of all the molecules of a given substance.