Final answer:
The question focuses on thermal expansion in physics, where a steel bar expands when heated. It involves concepts like the coefficient of linear expansion, specific heat capacity, and the potential stress induced in materials that cannot expand freely. Therefore, the correct option is a) Thermal expansion.
Step-by-step explanation:
The student's question relates to the concept of thermal expansion in physics, which is the tendency of matter to change its shape, area, and volume in response to a change in temperature. When a steel bar is heated, it expands due to the increase in kinetic energy of its particles causing an increase in separation between them.
The calculation of this expansion for steel involves the use of the linear expansion formula ΔL = αLΔT, where ΔL is the change in length, α is the coefficient of linear expansion, L is the original length, and ΔT is the change in temperature.
Specific heat capacity, another concept mentioned in the question, refers to the amount of heat energy required to raise the temperature of a substance by one degree Celsius. If the steel bar cannot expand, it may generate stress due to thermal expansion, calculated using Hooke's law and material properties like Young's modulus.
Additionally, the various properties must be taken into account while designing structures like the Eiffel Tower or railroad tracks to accommodate thermal expansion and prevent structural damage.