Question

Please help and show work for 1-4!

900 K + 800 J 400] A. Device 1, shown at right, represents a heat engine operating between reservoirs at 900 K and 400 K. (The system interacting with the reservoirs is represented by the dashed region.) The numbers and arrows indicate either thermal energy transfers or work done during each cycle. 1. How much work is done on the system during each cycle? Be sure to indicate whether it is positive or negative. Won system HN 400 J 400 K Device 1 2. How much energy is transferred thermally to the system from the high temperature reservoir during each cycle? Be sure to indicate whether it is positive or negative. Olt (to system) = 3. How much energy is transferred thermally to the system from the low temperature reservoir during each cycle? Be sure to indicate whether it is positive or negative. OL(o vystem) 4. The first law of thermodynamics can be written as AE. Qio system + Woon . Use it to find the change in internal energy of the system during each cycle. Show your work. Is your result consistent with the idea that energy is a state function? Explain.

Answer 1

1)

W_on system = Q_H -Q_L = 800 -400 = 400 J

work done on system = -400 J

2)

Q_H = +800 J

3)

Q_L = -400 J

4)

ΔE_int = Q_{to system} + W_{on system}

= 400 + -400 = 0

so change in the internal energy in each cycle = 0

and this answer proves that internal energy is a state fucntion becuse in each cycle it will be zero