Question

In a process, the work done by the system is equal to the decrease in its internal energy. The process that the system undergoes is: 

• A. isothermal process
• B. adiabatic process
• C. isobaric process
• D. isochoric process

Answer 1

The Correct Option is B

To solve the problem, we need to identify the thermodynamic process in which the work done by the system is equal to the decrease in its internal energy.

1. Understanding the First Law of Thermodynamics:
The first law states:
$ \Delta Q = \Delta U + W $
Where:
- $\Delta Q$ is the heat added to the system
- $\Delta U$ is the change in internal energy
- $W$ is the work done by the system

2. Given Condition:
The system does work, and the decrease in internal energy is equal to the work done. That is:
$ W = -\Delta U $
Substitute into the first law:
$ \Delta Q = \Delta U + W = \Delta U - \Delta U = 0 $

3. Conclusion from Zero Heat Transfer:
If $ \Delta Q = 0 $, it means no heat is exchanged with the surroundings. This is the definition of an adiabatic process.

Final Answer:
The process is an adiabatic process.

Answer 2

The correct option is: (B): adiabatic process.

In line with the first law of thermodynamics, the equation states that:

dQ = dU + dW

Given that dW = -dU, it follows that:

dQ = 0

As a result, the heat transfer within the system equals zero. Consequently, this implies the process could be adiabatic.