Sample interview questions: How do you define thermal expansion and its consequences?
Sample answer:
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Thermal Expansion:
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Definition: Thermal expansion is a physical phenomenon where substances undergo a change in volume when there is a change in temperature. This volumetric change is a consequence of the changes in interatomic or intermolecular distances and angles.
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Consequences of Thermal Expansion:
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Changes in Density: As a substance’s volume changes with temperature, its density also changes. Typically, substances expand when heated (i.e., volume increases) and contract when cooled (i.e., volume decreases).
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Thermal Stress: When different parts of an object experience different temperature changes, non-uniform thermal expansion can occur. This can lead to the development of thermal stresses within the material, potentially causing warping, cracking, or even failure.
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Expansion Joints: In engineering applications, thermal expansion must be accounted for and managed. Expansion joints are often used in pipelines, bridges, and other structures to allow for the expected changes in volume and prevent damage.
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Liquid Expansion: Liquids typically expand more than solids when heated. This phenomenon is used in thermometers, where the expansion of a liquid (e.g., mercury or alcohol) is used to indicate temperature changes.
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Gas Expansion: Gases are highly expansive and show significant volume changes with temperature variations. This property is used in hot air balloons, where heated air expands and becomes less dense, causing the balloon to rise.
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Phase Transitions: Thermal expansion can play a role in phase transitions, such as melting and boiling. As a substance’s temperature increases, its molecules gain more energy, causing an increase in intermolecular s… Read full answer