Thermal Properties Of Matter

-273.15 C.

Answer (a) expand

The walls first expand inside and outside both and then towards outside more.

Because iron is towards inside when the metallic strip is heated.

Black is a good absorber and also a good emitter

Pyrometer is used to measure very high temperatures.

When cooled from room temperature liquid water becomes dense, as with other substances, but at approximately (39 F), pure water reaches its maximum density. If it is cooled further, it expands to become less dense.

Key concept According to principle of calorimetry states that total heat given by a hotter body is equal to the total heat received by colder body
i.e. heat lost by hotter body = heat gained by colder body
Heat required to melt of ice at into of water at is .
Heat required to convert of water at into of water at
Heat required to condense of steam

Clearly, whole of steam is not condensed. So, temperature of the mixture is .

Key Idea When temperature difference is not large, rate of temperature change is given by Newton'8 law of cooling. In first case,
Average temperature

Excess temperature
Rate of fall in temperature,



(i)
In second case,
Average temperature

Excess temperature

Rate of fall in the temperaturre


(ii)
On dividing E (i) by E (ii), we get

I

ii