Question

Which of the processes described below are irreversible?

1. The increase in temprature of an iron rod by hammering it.
2. A gas in a small cantainer at a temprature T₁ is brought in contact with a big reservoir at a higher temprature T₂ which increases the temprature of the gas.
3. A quasi-static isothermal expansion of an ideal gas in cylinder fitted with a frictionless piston.
4. An ideal gas is enclosed in a piston cylinder arrangement with adiabatic walls. A weight W is added to the piston, resulting in compression of gas.

Answer 1

a. b and d

Explanation:

a. When the rod is hammered, external work is done on the rod which increases its temperature. The process cannot be retraced itself.

b. In this process energy in the form of heat is transferred to the gas in the small container by a big reservoir at temperature T₂.

d. As the weight is added to the cylinder arrangement in the form of external pressure hence, it cannot be reversed back itself.