Chapter 6, Problem 6.8E

A system in which there is no transfer of matter across the boundary. It consists a fixed amount of mass, and no mass can cross its boundary. That is, no mass can enter or leave a closed system

Krypton in a closed system is compressed adiabatically from 74 K and 1 bar to a final pressure of 24 bar. What is the final temperature in K? Assume krypton is an ideal gas. From Appendix B in the text, we can assume the heat capacity of krypton is independent of temperature and CP=2.5R , where R is the molar gas constant R=8.314 J/(mol K). For an ideal gas, recall CV=CP−R=1.5R. Report your answer in units of K using three decimal places.

Calculate the amount of work necessary for the reversible compression of steam from 1 bar to 10 bar. The compression is to take place in a cylinder fitted with a weightless piston at the constant temperature of 500 oC. Under these conditions we have a superheated vapor. Report your answer in units of kJ/kg using three decimal places. As you check your work, note that here we have compression from 1 bar to 10 bar under constant temperature. We would expect the volume of the system to decrease. Use this to check the sign (positive or negative) of your computed work.

Consider the PV diagram as shown above when a thermodynamic system changes its state from state a to state b. With the assumption that the system changes only in its internal energy therefore the changes in internal energy along any of the 3 paths are numerically equal. Be mindful of the directions of the arrows. When a system is taken from state a to state b along the path acb, 140 J of heat flows into the system and the system does 60 J of work. If the work done on the system is 20 J when the system returns from b to a along path bda, the amount of heat in J that is either absorbed or liberated is -90 O- 70 - 100 -110

Temperature is an extensive property. True or False? Explain.

A gas is contained in a vertical piston-cylinder assembly by a piston with a face area of 50 in² and weight of 100 lbf. The atmosphere exerts a pressure of 14.7 lb/in² on top of the piston. A paddle wheel transfers 3 Btu of energy to the gas during a process in which the elevation of the piston increases slowly by 2 ft. The piston and cylinder are poor thermal conductors, and friction between the piston and cylinder can be neglected. Determine the work done by the gas on the piston, in Btu, and the change in internal energy of the gas, in Btu. * Your answer is incorrect. Determine the expansion work done by the gas on the piston, in Btu. Wexp = i 0.854 Btu

3. The movement of a piston in a cylinder is restrained by a spring with a spring constant K=250lbf/in. At a position of x=0 the force exerted by the spring on the piston is 0lbf. How much work is done (in Btu) on the spring by the piston when the piston has moved 2in (compressed the spring 2in)? a.Sketch the problem. b.Draw lines identifying the control volume, or control mass. c.Identify the states with numbers, letters, or descriptions such as “in” and “out”. d.Write down the knowns and unknowns. e.Identify what is being asked for f.State all assumptions.

An example of a force is: The mass of an object. The action of one body on another. A scalar quantity. The velocity of the object.

Work is done on an adiabatic system due to which its velocity changes from 10 m/s to 20 m/s, elevation increases by 20 m and temperature increases by 1 K. The mass of the system is 10 kg, Cv = 100 J/kg-K and gravitational acceleration is 10 m/s² .if there is no change in any other component of the energy of the system, find out the magnitude of total work done on the system.