We consider a thermodynamic system. If Δ U represents the increase in its internal energy and W the work done by the system, which of the following statements is true? (a) Δ U = -W in an adiabatic process (b) Δ U = W in an isothermal process (c) Δ U = -W in an isothermal process (d) Δ U = W in an adiabatic process

Answer: (a). First law: Δ Q = Δ U + W. Adiabatic: Δ Q = 0 ⇒ Δ U = -W. Isothermal: Δ U = 0, so (b) and (c) are wrong; (d) has the wrong sign. So the answer is (a) Δ U = -W in an adiabatic process.

We consider a thermodynamic system. If Δ U represents the increase in… | NEET 1998 (AIPMT)

Q248NEET 1998 · AIPMTEasy

Thermodynamic Processes

We consider a thermodynamic system. If $\Delta U$ represents the increase in its internal energy and $W$ the work done by the system, which of the following statements is true?

Show answer and solution

Answer: (a)

First law: $\Delta Q = \Delta U + W$ .
Adiabatic: $\Delta Q = 0 \Rightarrow \Delta U = -W$ .
Isothermal: $\Delta U = 0$ , so (b) and (c) are wrong; (d) has the wrong sign.
So the answer is (a) $\Delta U = -W$ in an adiabatic process.

Report a mistake

Thermodynamic Processes question from NEET 1998 (AIPMT)

More questions on Thermodynamic Processes