Using the analogy between thermodynamics and electricity, two new concepts of thermal charge and quantity of thermal charge are introduced. A simple yet explicit definition of entropy is then derived-entropy is the quantity of thermal charge. As a result, quantity of thermal charge (entropy) and quantity of heat (energy) are now clearly…

This work presents the design of an inexpensive electronic system to measure water temperature and generate an experimental data set used to verify the fitting between experimental and theoretical curves of a water-cooling process. The cooling constant is computed with three different theoretical methods to check their efficiency and this approach…

We present a thermodynamics experiment suitable for first year undergraduate students employing Stirling Engines to create a demonstration of energy transformation and to measure the mechanical efficiency of such engines. Using an inexpensive transparent chambered Stirling Engine, students can connect concepts such as the theoretical…

The overarching goal of this paper is to illustrate the interplay between theory, design principles, and curriculum (meant broadly, to include both written and enacted curriculum). This dialogue is illustrated in the context of the design and implementation of a particular curricular unit on thermodynamics intended for advanced secondary students…

Stars form from large clouds of gas and dust that contract under their own gravity. The birth of a star occurs when a fusion reaction of hydrogen into helium is ignited in its core. The key variable that determines the formation of a star is mass. If the mass of the contracting cloud is below a certain minimum value, instead of a star, a substelar…

In his interesting and informative book "Is That a Fact?," Joe Schwarcz avers that pigs do not sweat and the saying "sweating like a pig" originates in iron smelting. Oblong pieces of hot iron, with a fancied resemblance to a sow with piglets, cool in sand to the dew point of the surrounding air, and hence water condenses on…

A low-cost alternative to the typical scientific laboratory water bath or a hot plate stirrer water bath is proposed. Readily available immersion circulators have been developed for sous vide cooking. These precision cookers are designed to maintain water at an exact temperature and thus are well-suited for the similar laboratory requirements of a…

The expansion or compression of gas confined in a piston-and-cylinder device is a classic working example used for illustrating the First and Second Laws of Thermodynamics. The balance of energy and entropy enables the estimation of a number of thermodynamic properties. The entropy generation (also called entropy production) resulting from this…

The two independent methods of measurement of the mass of ice created at sudden solidification of supercooled water are described. One is based on the calorimetric measurement of heat that is necessary for melting the ice and the second interprets the volume change that accompanies the water freezing. Experimental results are compared with the…

The relationship between physics and mathematics is hardly ever presented with sufficient clarity to satisfy either physicists or mathematicians. It is a situation that often leads to misunderstandings that may spread quickly from teacher to student, such as the idea that mathematics is a mere instrument for the physicist. In this paper, we…

In this article we discuss the concept of equilibrium establishment in four most usual instances as is electrostriction and vaporization as related to the concept of equilibrium shell formation. Two more cases are then studied which are of relevance. One is the Brownian movement, the study of which is essential for pedagogical reasons as to…

This work explores the concept of dissipative work and shows that such a kind of work is an invariant non-negative quantity. This feature is then used to get a new insight into adiabatic irreversible processes; for instance, why the final temperature in any adiabatic irreversible process is always higher than that attained in a reversible process…

A proper First Law energy balance of the soybean biodiesel cycle shows that the overall efficiency of biodiesel production is 0.18, i.e., only 1 in 5 parts of the solar energy sequestered as soya beans, plus the fossil energy inputs, becomes biodiesel. Soybean meal is produced with an overall energetic efficiency of 0.38, but it is not a fossil…

This paper aims to contribute to a better understanding of convective heat transfer. For this purpose, the reason why thermal diffusivity should be placed before the Laplacian operator of the heat flux, and the role of the velocity gradient in convective heat transfer are analysed. The background to these analyses is that, when the energy…

In this work, we review two formalisms of coherent states for the case of a particle in a magnetic field. We focus our revision on both pioneering (Feldman and Kahn 1970 "Phys. Rev." B 1 4584) and recent (Kowalski and Rembielinski 2005 "J. Phys. A: Math. Gen." 38 8247) formulations of coherent states for this problem. We introduce a general…