NCERT Class 11 Physics Solutions: Chapter 11 – Thermal Properties of Matter-Part 5

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Question 11.11:

The coefficient of volume expansion of glycerin is . What is the fractional change in its density for a rise in temperature?

Answer:

Coefficient of volume expansion of glycerin,

Rise in temperature,

Fractional change in its volume

This change is related with the change in temperature as:

Where,

Mass of glycerin

Initial density at

Final density at

Fractional change in density

Fractional change in the density of glycerin

Question 11.12:

A drilling machine is used to drill a bore in a small aluminium block of mass . How much is the rise in temperature of the block in , assuming of power is used up in heating the machine itself or lost to the surroundings. Specific heat of aluminum .

Answer:

Power of the drilling machine

Mass of the aluminum block,

Time for which the machine is used,

Specific heat of aluminum,

Rise in the temperature of the block after drilling

Total energy of the drilling machine

It is given that only of the power is useful.

Useful energy,

But

Therefore, in of drilling, the rise in the temperature of the block is

Question 11.13:

A copper block of mass is heated in a furnace to a temperature ofand then placed on a large ice block. What is the maximum amount of ice that can melt? (Specific heat of copper heat of fusion of water

Answer:

Mass of the copper block,

Rise in the temperature of the copper block,

Specific heat of copper,

Heat of fusion of water,

The maximum heat the copper block can lose,

Let be the amount of ice that melts when the copper block is placed on the ice block.

The heat gained by the melted ice,

Hence, the maximum amount of ice that can melt is