Author: haroonkhan

Heat and work are energy transfer mechanisms between a system and its surroundings. Some of the similarities between heat and work are as follows:

Heat and work are directional quantities, and thus the complete description of a heat or work interaction requires the specification of both the magnitude and direction. One way of doing that is to adopt a sign convention. The generally accepted formal sign convention for heat and work interactions is as follows:

Energy transfer across the boundary of a closed system may occur in the form of heat and work. When a closed system is left in a medium of different temperature, energy transfer takes place between the system and the surrounding until thermal equilibrium is reached. The direction of energy transfer is always from the higher…

Internal energy can be defined as the sum of all the microscopic forms of energy of a system. It is related to the molecular structure and the degree of activities at molecular level and can be viewed as the sum of the kinetic and potential energies of the molecules. Let us consider a system for…

Energy exists in various forms such as thermal, mechanical, kinetic, potential, electric, magnetic, chemical, nuclear, etc. In thermodynamics, it is considered that the various forms of energy make up total energy of a system. This total energy can be represented into two groups—macroscopic and microscopic. The macroscopic forms of energy are those a system possesses…

The machine, which would continuously supply mechanical work without some other form of energy disappearing simultaneously, is called first kind of perpetual motion machine (PMM1). PMM1 is impossible. It is a fictitious machine.

The first law of thermodynamics is equivalent to law of conservation of energy. It deals with the transformation of heat energy into work and vice versa. For closed systems, energy can be transferred by work and heat transfer. In thermodynamics, the term work denotes a means for transferring energy. Work done by a system is considered positive: W >…

Mechanical Equivalent of Heat The mechanical equivalent of heat is a concept that has an important part in the development and acceptance of the conservation of energy and the establishment of the science of thermodynamics in the 19th century. The concept stated that motion and heat are mutually interchangeable and that in every case, a given amount…

The rate of change of enthalpy with respect to absolute temperature when pressure is constant is known as specific heat at constant pressure (Cp). Example 1.1: The property of a substance is given as where u is the specific internal energy (kJ/kg), t is temperature in °C, p is pressure in kN/m2, and v is specific volume (m3/k). Find the Cv and Cp of the substance. Solution:

Thermodynamics: It is the field of thermal engineering that studies the properties of systems that have a temperature and involve the laws that govern the conversion of energy from one form to another, the direction in which heat will flow, and the availability of energy to do work. Mass and Force: Mass is one of the fundamental…