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### College Physics (Urone)

Book edition 1st Edition
Author(s) Paul Peter Urone
Pages 1272 pages
ISBN 9781938168000

# Describe the photo of the tea kettle at the beginning of this section in terms of heat transfer, work done, and internal energy. How is heat being transferred? What is the work done and what is doing it? How does the kettle maintain its internal energy?

The heat is transmitted to the tea kettle through the stove. The work done is the vaporization of water to the whistling of the tea kettle. The internal energy of the tea kettle is maintained by the process of heating the water inside it.

See the step by step solution

## Step 1: Heat Transmission

• The tea kettle on the stove absorbs the thermal energy yielded from the stove and utilizes it for the conversion of water into steam.
• When the whistling of the tea kettle is heard, the steam gets away.
• The fuel inside the stove burns and the chemical energy which is stored in the fuel is converted to thermal energy.
• Since the base of the tea kettle is a good conductor of heat, it absorbs and transfers to the water inside it. Hence the heat energy is transferred to the water inside it.

## Step 2: Work Done

• The temperature increases when the water assimilated energy. When the temperature increases the particles in the water vibrate with the increasing speed.
• The water in the kettle converts into steam when the temperature is increased and the water has reached its boiling point.
• Hence the work done is the intermolecular forces of the water which is converted into steam.
• The energy required for this process is taken from heat energy provided to the tea kettle.

## Step 3: Internal Energy

• Heat is continuously provided to the water which results in the vaporization of the water building up more pressure inside.
• The nozzle of the kettle has two thin plates which are separated by a small opening where the steam gets out.
• When the steam gets away within the small opening it expands and produces a sound vibration/whistling.
• The expansion of steam results in the increase of intermolecular separation. At the constant temperature, the water changes its state and according to thermodynamics first law, $$\Delta U = Q - W$$. Where $$\Delta U$$ is the change in the internal energy, $$W$$ is the work done by the system and $$Q$$ is the heat energy given to the kettle.
• Hence the evaporation of water to the whistling of the kettle is the work done and as the base of the kettle occupies heat and transfers to the water, the internal energy is maintained by heating the water.