Introduction
The first law of thermodynamics deals with the state of energy and its transfer between objects. According to this law, energy is conserved in an isolated system, and it can be transformed but not destroyed or created (Brown & Singh, 2021). Therefore, there are two ways to increase internal energy – transfer the heat or do work. The first type is transferring heat into the substance; if a container is filled with gas, putting it into boiling water could heat the container and transfer this heat into the gas. As an outcome, the gas molecules would move faster, and internal energy would be increased.
The second way of increasing internal energy is by doing work, such as compression. In an engine, a piston moves in a vacuum cylinder, and this motion compresses or expands the gas inside. When the piston moves downward, it reduces the volume that gas can take up, which means it does positive work. As a result, the gas molecules speed up, and the internal energy grows.
Potato with a Nail Scenario
A conventional oven operates by heating the product inside. Therefore, the cooking speed can be influenced by heat conductors – materials that help transfer heat to other objects. Metal is considered an excellent heat conductor, and its temperature rises quickly in an oven (Thermtest, 2020). Therefore, a nail inside the potato heats up, and the potato receives heat not only from the outside but also from the inside.
Conclusion
The three methods of heat transfer are conduction, convection, and radiation. First, conduction occurs through solids, when the energy is transferred by two molecules in direct contact (Xu et al., 2019). As mentioned above, metals are good heat conductors as the molecules inside are placed close to each other, allowing for better direct contact – touching a hot metal can be painful as the heat transfer is quick. Convection is the movement of heat through fluids – a current of hot air, for example, moves the energy from one object to another. Many examples can be found in cooking, including convection ovens or hot water. The final method is radiation, in which heat is transferred through electromagnetic waves. Feeling warm when standing under the sun is an example of radiation.
References
Brown, B., & Singh, C. (2021). Student understanding of the first law and second law of thermodynamics. European Journal of Physics, 42(6), 065702. Web.
Thermtest. (2020). Physics explanation of thermal conductivity of metals. Web.
Xu, H. J., Xing, Z. B., Wang, F. Q., & Cheng, Z. M. (2019). Review on heat conduction, heat convection, thermal radiation and phase change heat transfer of nanofluids in porous media: Fundamentals and applications. Chemical Engineering Science, 195, 462-483. Web.