Chapter 4, Problem 31P

Thermodynamics: Mass and Energy Analysis Of Control Volumes  A frictionless piston-cylinder device contains 4.5 kg of nitrogen at 110 kPa and 200 K. Nitrogen is nowcompressed slowly according to the relation PV1.5 = constant until it reaches a final temperature of 360 K.Calculate the work input during the process, in kJ.

Thermodynamics: Mass and Energy Analysis Of Control Volumes  An insulated piston-cylinder device contains 4 L of saturated liquid water at a constant pressure of 200 kPa.Water is stirred by a paddle wheel while a current of 8 A flows for 50 min through a resistor placed in thewater. If one-half of the liquid is evaporated during this constant-pressure process and the paddle-wheelwork amounts to 300 kJ, determine the voltage of the source. Also, show the process on a P–v diagram withrespect to the saturation lines.

Thermodynamics: Mass and Energy Analysis Of Control Volumes The state of liquid water is changed from 55 psia and 45◦F to 2000 psia and 120◦F. Determine the change inthe internal energy and enthalpy of water on the basis of the (a) compressed liquid tables, (b) incompressiblesubstance approximation and property tables, and (c) specific-heat model.

Thermodynamics: Mass and Energy Analysis Of Control Volumes What is the change in enthalpy, in kJ/kg, of oxygen as its temperature changes from 150 to 250◦C? Is thereany difference if the temperature change were from −50 to 100◦C? Does the pressure at the beginning andend of this process have any effect on the enthalpy change?

Thermodynamics: Mass and Energy Analysis Of Control Volumes  A 50-L electrical radiator containing heating oil is placed in a 50-m3 room. Both the room and the oil in theradiator are initially at 5◦C. The radiator with a rating of 3 kW is now turned on. At the same time, heatis lost from the room at an average rate of 0.3 kJ/s. After some time, the average temperature is measuredto be 20◦C for the air in the room, and 60◦C for the oil in the radiator. Taking the density and the specificheat of the oil to be 950 kg/m3 and 2.2 kJ/(kg◦C), respectively, determine how long the heater is kept on.Assume the room is well-sealed so that there are no air leaks.

Problem 3 For the beam and loading shown, consider section n-n and determine (a) the largest shearing stress in that section, (b) the shearing stress at point a. 1ft 15 kips 20 kips 15 kips AITT in 1 0.6 in. -10 in. 1 in. 0.375 in.- 2 ft 2ft 2 ft 2ft 10 in. 1 0.6 in.

practice problems want detailed break down

6.105. Determine force P on the cable if the spring is compressed 0.025 m when the mechanism is in the position shown. The spring has a stiffness of k = 6 kN/m. E P 150 mm D T 30° 200 mm 200 mm 200 mm B 800 mm

6.71. Determine the reactions at the supports A, C, and E of the compound beam. 3 kN/m 12 kN A B CD E -3 m 4 m 6 m 3 m 2 m