Question

Consider the following scenario. You grab a box of cereal from your pantry, and you carry it over to your table. When you get there, you change your mind and return the box of cereal to its original spot. Is this a reversible process if the closed system is your house/apartment? Explain your answer

Answer 1

No, the given process is not reversible. A process can be reversible only if all the heat and energy changes can be reversed back on changing the direction of process such that the entropy change of system and surrounding is zero.

In the given scenario, as you grab your box of cereal and carry it over the table, you do some work against the friction force offered by the ground as well as the viscous force offered by the air. As a result of this work, you dissipate energy to room in the form of heat. Now if on moving back from table to pantry, you could gain the heat lost previously then the process would become reversible but as you move back you again have to do work against friction because friction always opposes you so since heat is dissipated both the times as a result the temperature of the room will rise or we can say the entropy of the room will increase hence process is not reversible.