Rehydration Salt Sugar

Introduction

Ce premier cours a pour objectif de poser les notions essentielles pour le développement du cours, de vérifier que les élèves possèdent ces connaissances et les significations physiques qui y sont rattachées.
La première partie a permis d'établir le principe de conservation de l'énergie pour un système fermé. La notion d'énergie interne est abordée et le fait qu'elle comprend l'énergie cinétique et l'énergie potentielle. Nous avons également adopté la convention de signe pour les échanges d'énergie : Positive when the system receives energy, negative when he gives.
In a second part, the open systeem are discussed and then it appears that the exchange of energy can also be done in the form of a mass exchange. This will lead us to establish a new equation for the principle of conservation of energy (next class). To clarify this notion of open system, the example of the power plant is discussed. It is noted that if the different components of the central thermiqe (boiler, turbine, condenser, pump, pipes) are open systems, the installation taken as a whole is a closed system.
In the third part, we distinguish between extensive quantities (volume, mass, energy) and intensive quantities (pressure, temperature). In the remainder of the course we will bring the extensive magnitudes in intensive magnitudes by dividing by the mass. To distinguish them from other quantities, the mass quantities will always be represented as lowercase letters.
To complete the course, he addressed the notion of state function, which are mathematically exact differential forms, which means physically that their variation does not depend on the path followed during processing. The Energy House is a state function. By cons, work and heat are not state functions.