No, the long run is not solely the case in which we only use variable input in economics. In economics, the long run refers to a time period in which all inputs can be varied and adjusted, including both variable inputs (such as labor, raw materials, etc.) and fixed inputs (such as capital, machinery, etc.). The distinction between the short run and the long run is based on the degree of flexibility in adjusting various inputs in production. In the short run, at least one input is fixed and cannot be changed, while in the long run, all inputs can be adjusted.
