Question

P2-44 A piston-cylinder assembly of total mass 16 lbm is free to move within a housing....

P2-44 A piston-cylinder assembly of total mass 16 lbm is free to move within a housing. Initially the cylinder contains gas at an absolute pressure of 20 Ibf/in^2 and a volume of 0.07 ft^3 and is at rest. The piston is then moved so that the entire assembly accelerates rightward and reaches a final velocity of 7.5 ft/s. During this process, the gas is compressed to a final pressure of 35 Ibf/in^2 The process is adiabatic, and the pressure is related to the volume by PV^1.4= constant. Calculate the change in internal energy for this process in Btu.

Homework Answers

Answer #1

Given data for the process:  

Initial pressure = 20 lbf/in^2        

initial volume = 0.07 ft^3    = 120.96 inch^3               (1 ft^3 = 1728 inch^3 )

Final pressure = 35 lbf/in^2         

process is adiabatic, For adibatic pressure

For adiabatic process, Workdone

or Work in the said process ( in unit of lbf-ft)

From First Law of thermodynamics,

dQ = 0   in this case of adiabatic process

dU = Change in internal energy

dW = work interaction in the process

therefore dU = change in internal energy for the process is

So internal energy of the system will increases by +87.3833 lbf-ft

Now , we know that   1 Btu = 778.16 lbf-ft

Hence

internal energy of the system will increases by 0.11229 Btu.

Know the answer?
Your Answer:

Post as a guest

Your Name:

What's your source?

Earn Coins

Coins can be redeemed for fabulous gifts.

Not the answer you're looking for?
Ask your own homework help question
Similar Questions
A piston cylinder contains 2 lbm of air and operates at a constant pressure of 400...
A piston cylinder contains 2 lbm of air and operates at a constant pressure of 400 psia. The initial volume is 1 ft.3 and the initial temperature is 100°F. The final volume is 4 ft.3 and the final temperature is 1780°F. Determine the work and its direction (in or out) and the heat transfer and its direction, in Btu/lbm.
A gas contained in a vertical piston–cylinder assembly by a piston with a face area of...
A gas contained in a vertical piston–cylinder assembly by a piston with a face area of 40 in2 and weight of 100 lbf. The atmosphere exerts a pressure of 14.7 lbf/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 4 ft. The piston and cylinder are poor thermal conductors, and friction between the piston and cylinder can be neglected....
A gas undergoes a process in a piston–cylinder assembly during which the pressure-specific volume relation is...
A gas undergoes a process in a piston–cylinder assembly during which the pressure-specific volume relation is pv1.2 = constant. The mass of the gas is 0.4 lb and the following data are known: p1 = 160 lbf/in.2, V1 = 1 ft3, and p2 = 300 lbf/in.2 During the process, heat transfer from the gas is 2.1 Btu. Kinetic and potential energy effects are negligible. Determine the change in specific internal energy of the gas, in Btu/lb. Δu⁢=
Steam, initially at 700 lbf/in.2, 550°F undergoes a polytropic process in a piston–cylinder assembly to a...
Steam, initially at 700 lbf/in.2, 550°F undergoes a polytropic process in a piston–cylinder assembly to a final pressure of 2200 lbf/in.2 Kinetic and potential energy effects are negligible. Determine the heat transfer, in Btu per lb of steam, for a polytropic exponent of 1.4, (a) using data from the steam tables. (b) assuming ideal gas behavior.
An insulated cylinder is fitted with an airtight piston that is free to slide up and...
An insulated cylinder is fitted with an airtight piston that is free to slide up and down and is connected to a rod, as shown in the figure. Contained within the cylinder is an ideal gas initially at a pressure of 120 kPa and temperature of 293 K. Suddenly the piston is forced downward creating an additional 200 kPa of pressure on the gas and as a result the cylinder volume decreases to one-half of its original volume. (a) What...
An insulated cylinder is fitted with an airtight piston that is free to slide up and...
An insulated cylinder is fitted with an airtight piston that is free to slide up and down and is connected to a rod. Contained within the cylinder is an ideal gas initially at a pressure of 120 kPa and temperature of 293 K. Suddenly the piston is forced downward creating an additional 200 kPa of pressure on the gas and as a result the cylinder volume decreases to one-half of its original volume. (a) What is the final temperature of...
Carbon dioxide (CO2) is compressed in a piston–cylinder assembly from p1 = 0.7 bar, T1 =...
Carbon dioxide (CO2) is compressed in a piston–cylinder assembly from p1 = 0.7 bar, T1 = 280 K to p2 = 14 bar. The initial volume is 0.2 m3. The process is described by pV1.25 = constant. Assuming ideal gas behavior and neglecting kinetic and potential energy effects, determine the work and heat transfer for the process, each in kJ, using constant specific heats evaluated at 300 K, and data from Table A-23.
A piston-cylinder assembly containing 3 kg of an ideal gas undergoes a constant pressure process from...
A piston-cylinder assembly containing 3 kg of an ideal gas undergoes a constant pressure process from an initial volume of 48 m3 to a final volume of 30 m3 . During the process, the piston supplies 1.2 MJ of work to the gas. The gas has a constant specific heat at constant volume of 1.80 kJ/(kg∙K) and a specific gas constant of 1.48 kJ/(kg∙K). Neglect potential and kinetic energy changes. a. Determine the initial specific volume of the gas in...
Water undergoes a constant‐volume process within a piston–cylinder assembly from saturated liquid at 4 bar to...
Water undergoes a constant‐volume process within a piston–cylinder assembly from saturated liquid at 4 bar to a final pressure of 50 bar. Kinetic and potential energy effects are negligible. Determine the work and the heat transfer, each in kJ per kg of water. [7 points]