Question

Consider a cycle followed by an engine as shown in figure 1 to 2 is isothermal 2 to 3 is adiabatic 3 to 1 is adiabatic Such a process does not exist because

• A. Heat is completely converted to mechanical energy in such a process, which is not possible.
• B. Mechanical energy is completely converted to heat in this process, which is not possible.
• C. Curves representing two adiabatic processes can intersect.
• D. Curves representing an adiabatic process and an isothermal process don’t intersect.

Answer 1

Answer: (A)

Heat is completely converted to mechanical energy in such a process, which is not possible.

Answer 2

: In one complete cycle, $1 \rightarrow 2 \rightarrow 3 \rightarrow 1$the system returns to its initial state so dU = 0 and dQ = dW i.e. heat is completely converted into mechanical energy in the given process, it is not possible further two adiabatic curve $2 \rightarrow 3$ and $3 \rightarrow 1$ cannot intersect each other.