Question

Which would be a more reversible process?
answers below:
Putting a brick on a piston and then taking it off

Putting a bag of sand on a piston, and then removing one grain of sand at a time.

Answer 1

In terms of reversibility, putting a brick on a piston and then taking it off would be a more reversible process.

This is because the action of placing a brick on the piston and removing it involves relatively straightforward mechanical processes that do not significantly alter the system or its environment. You can place the brick back on the piston in the same state without any residue or lasting effects.

In contrast, adding sand one grain at a time introduces a more complex interaction. The act of removing grains of sand can lead to changes in the distribution and arrangement of the remaining sand, potentially affecting the overall system in ways that are difficult to fully reverse. Additionally, this process could lead to changes in pressure distribution and may not return the system to its exact original state.

Hence, placing a brick on a piston and then taking it off is generally considered to be a more reversible process.