What is the definition of work in thermodynamics?

Work in thermodynamics is defined specifically as the transfer of energy that occurs when a force moves an object through a distance. This definition emphasizes that work involves motion against an opposing force, such as pushing a piston in a gas or lifting an object against gravitational pull. In these scenarios, energy is transferred to the system by performing work, and this is quantified as the product of the force exerted and the distance moved in the direction of that force.

The concept of work is critical in thermodynamic processes, particularly when considering how energy is exchanged within systems. For example, in isothermal processes, where temperature remains constant, while energy can be exchanged through heat, it is the work done that contributes to the overall changes in the energy state of the system.

This understanding helps differentiate work from other forms of energy transfer, such as heat, which can occur without any physical motion. Therefore, identifying work as energy transferred by motion against an opposing force captures its essence in thermodynamic contexts.