what subchapters in College Physics 2e openstax do i need to read to cover this content? Thermal Expansion and Kinetic Theory

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Thermal Expansion
Linear expansion
occurs when an object
is heated.

Here, α is the coefficient of linear
expansion.
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Thermal Expansion
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Thermal Expansion
Example: Bridge expansion.
The steel bed of a suspension bridge is 200 m long at 20°C. If the extremes of temperature to which it might be exposed are -30°C to +40°C, how much will it contract and expand?
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Thermal Expansion
Conceptual Example: Do holes expand or contract?
If you heat a thin, circular ring in the oven, does the ring’s hole get larger or smaller?
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Thermal Expansion
Example: Ring on a rod.
An iron ring is to fit snugly on a cylindrical iron rod. At 20°C, the diameter of the rod is 6.445 cm and the inside diameter of the ring is 6.420 cm. To slip over the rod, the ring must be slightly larger than the rod diameter by about 0.008 cm. To what temperature must the ring be brought if its hole is to be large enough so it will slip over the rod?
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Thermal Expansion
Conceptual Example: Opening a tight jar lid.
When the lid of a glass jar is tight, holding the lid under hot water for a short time will often make it easier to open. Why?
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Thermal Expansion
Volume expansion is similar, except that it is relevant for liquids and gases as well as solids:

Here, β is the coefficient of volume
expansion.
For uniform solids, β ≈ 3α.
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Thermal Expansion
Example: Gas tank in the Sun.
The 70-liter (L) steel gas tank of a car is filled to the top with gasoline at 20°C. The car sits in the Sun and the tank reaches a temperature of 40°C (104°F). How much gasoline do you expect to overflow from the tank?
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Thermal Expansion
Water behaves differently from most other solids—its minimum volume occurs when its temperature is 4°C. As it cools further, it expands, as anyone who leaves
a bottle in the freezer to cool and then forgets about it can testify.
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Atomic Theory of Matter
Atomic and molecular masses are measured in unified atomic mass units (u). This unit is defined so that the carbon-12 atom has a mass of exactly 12.0000 u. Expressed in kilograms:
1 u = 1.6605 x 10-27 kg.
Brownian motion is the jittery
motion of tiny flecks in water;
these are the result of
collisions with individual water
molecules.
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Atomic Theory of Matter
On a microscopic
scale, the
arrangements of
molecules in solids
(a), liquids (b), and
gases © are quite
different.
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Atomic Theory of Matter
Example: Distance between atoms.
The density of copper is 8.9 x 103 kg/m3, and each copper atom has a mass of 63 u. Estimate the average distance between the centers of neighboring copper atoms.
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Thermal Equilibrium and the Zeroth Law of Thermodynamics
Two objects placed in thermal contact will eventually come to the same temperature. When they do, we say they are in thermal equilibrium.
The zeroth law of thermodynamics says that if two objects are each in equilibrium with a third object, they are also in thermal equilibrium with each other.
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The Ideal Gas Law and the Molecular Interpretation of TemperatureThe force exerted on the wall by

the collision of one molecule is

Then the force due to all
molecules colliding with that
wall is

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The Ideal Gas Law and the Molecular Interpretation of Temperature
The averages of the squares of the speeds in all three directions are equal:

So the pressure is:

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The Ideal Gas Law and the Molecular Interpretation of Temperature
Rewriting,
so

The average translational kinetic energy of the molecules in an ideal gas is directly proportional to the temperature of the gas.
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The Ideal Gas Law and the Molecular Interpretation of Temperature
Example 18-1: Molecular kinetic energy.
What is the average translational kinetic energy of molecules in an ideal gas at 37° C?
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The Ideal Gas Law and the Molecular Interpretation of Temperature
We can now calculate the average speed of molecules in a gas as a function of
temperature:

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Distribution of Molecular Speeds
The molecules in a gas will not all have the same speed; their distribution of speeds is called the Maxwell distribution:


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Distribution of Molecular Speeds
The Maxwell distribution depends only on the absolute temperature. This figure shows distributions for two different temperatures; at the higher temperature, the whole curve is shifted to the right.

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