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?

Question

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.

Tardigrade Admin · Accepted Answer

From first law of thermodynamics, Δ Q = Δ U + W For an adiabatic process, Δ Q = 0 ∴ : :: Δ U = - W For an isothermal process, Δ U = 0 ∵ : : Δ T = 0 ∴ : :: : Δ Q = W

Q. 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?

$Δ U = - W$ in an adiabatic process.

$Δ U = W$ in an isothermal process.

$Δ U = - W$ in an isothermal process.

$Δ U = W$ in an adiabatic process.

From first law of thermodynamics,
$Δ Q = Δ U + W$
For an adiabatic process,
$Δ Q = 0$
$∴ Δ U = - W$
For an isothermal process,
$Δ U = 0$ $∵ Δ T = 0$
$∴ Δ Q = W$

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

ΔU=−W in an adiabatic process.

ΔU=W in an isothermal process.

ΔU=−W in an isothermal process.

ΔU=W in an adiabatic process.