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The black grille on the back of a refrigerator has a surface temperature of 35oC. How much energy can be removed during 15 minutes of operation?
Find the final temperature. Has the final state more or less vapor than the initial state? Find the final temperature and specific volume.
Discuss the results and the requirements for a substance to be a potential refrigerant.
Which process will lead to the larger work output: an isothermal process or a polytropic process with n = 1.25?
The valve is opened and stays open while the water in the two tanks comes to a uniform final state. Which two properties determine the final state?
A linear spring, F = ks(x - x0) with spring constant ks = 500 N/m, is stretched until it is 100 mm longer. Find the required force and the work input.
If 25 J is the work input to the master cylinder, what is the force and displacement of each piston and the work output of the slave cylinder piston?
A rigid tank with pressurized air is used (a) to increase volume of a linear spring-loaded piston. What is the expression for the work term in each situation?
Look at the R-410a value for uf at -50oC. Can the energy really be negative? Explain.
The setup is cooled at constant pressure until the R-134a reaches a quality of 25%. Calculate the work done in the process.
Air goes through a polytropic process from 125 kPa and 325 K to 300 kPa and 500 K. Find the polytropic exponent n and the specific work in the process.
It is now compressed to a pressure of 500 kPa in a polytropic process with n = 1.5. Find the final volume and temperature and determine the work done.
How much of a temperature difference from the ambient surroundings at 20oC must the refrigerator have in its heat exchanger with an area of 1 m2.
Can the butane reasonably be assumed to behave as an ideal gas at this state? Estimate the saturation pressure of chlorine at 300 K.
Determine the pressure of nitrogen at 160 K, v = 0.00291 m3/kg using the Soave EOS and the nitrogen table.
Heat is now added until the temperature reaches 200oC. Find the final pressure and also the quality if the water is in the two-phase region.
When the pressure drops to 18 psia, the flow of helium stops by itself. If all the helium is still at 540 R, how big a balloon is produced?
How much mass should the petcock have to allow boiling at 250 F with an outside atmosphere of 15 psia?
A glass jar is filled with saturated water at 300 F and quality 25%, and a tight lid is put on. What is the mass fraction of solid at this temperature?
What is the percent change in volume as liquid water freezes? Mention some effects the volume change can have in nature and in our households.
What is the lowest temperature (approximately) at which water can be liquid? Some tools should be cleaned in liquid water at 150oC. How high a P is needed?
List the range of pressures normally recorded as the systolic (high) and diastolic (low) pressures, and present your findings in a short report.
Write a program to convert a measured resistance, R, into information about the temperature.
Why is any calibration or correction necessary when it is used in an instrument?
Make a list of different weights and scales that are used to measure mass directly or indirectly. Investigate ranges of mass and accuracy that can be obtained.