Thermodynamics Physics - Thermodynamics

Consider $P-V$ diagram for an ideal gas shown in:

Out of the following diagrams which represents the $T-P$ diagram?

• A
  $(iv)$
• B
  $(ii)$
• ✓
  $(iii)$
• D
  $(i)$

Answer: C.

An ideal gas undergoes cyclic process ABCDA as shown in given PV diagram. The amount of work done by the gas is:

• A
  $6\text{P}_0\text{V}_0$
• B
  $-2\text{P}_0\text{V}_0$
• C
  $+2\text{P}_0\text{V}_0$
• ✓
  $+4\text{P}_0\text{V}_0$

Answer: D.

Consider a heat engine as shown in $Q_1$ and $Q_2$ are heat added to heat bath $T_1$ and heat taken from $T_2$ in one cycle of engine. W is the mechanical work done on the engine. If $\mathrm{W}>0$, then possibilities are:

• ✓
  $\text{Q}_1>\text{Q}_2>0$
• B
  $\text{Q}_2>\text{Q}_1>0$
• C
  $\text{Q}_2<\text{Q}_1<0$
• D
  $\text{Q}_1<0,\text{Q}_2>0$

Answer: A.

• ✓
  $b$ and $d$
• B
  $b$ and $c$
• C
  $a$ and $d$
• D
  $c$ and $d$

Answer: A.

Figure. shows the $\text{P-V}$ diagram of an ideal gas undergoing a change of state from $A$ to $B$. Four different parts $\text{I, II, III}$ and $\text{IV}$ as shown in the figure may lead to the same change of state.

1. Change in internal energy is same in $\text{IV}$ and $\text{III}$ cases, but not in $\text{I}$ and $\text{II.}$
2. Change in internal energy is same in all the four cases.
3. Work done is maximum in case $\text{I}$
4. Work done is minimum in case $\text{II.}$

• A
  $1$ and $2$
• ✓
  $1$ and $3$
• C
  $1$ and $4$
• D
  $2$ and $3$

Answer: B.