By age 6

A particular lake has been isolated and unchanged for more than a thousand years.  One day a company buys the property the lake is on and tries to turn the lake into a self-sustaining fish farm.  Unfortunately, there just aren’t enough nutrients in this lake to support a self-sustaining ecosystem capable of producing large fish so the company goes out of business.  How would you describe this lake’s water quality?

The best system for removing nutrients and other contaminants from water is a/an (?).

A rigid copper tank, initially containing 2 m^3 of nitrogen at 300 K, 1 bar, is connected by a valve to a large supply line carrying nitrogen at 300 K, 20 bar. The valve is opened only as long as required to fill the tank with nitrogen to a pressure of 20 bar. Finally, the nitrogen in the tank is at 310 K. The copper tank, which has a mass of 10 kg, is at the same temperature of the air in the tank, initially and finally. The specific heat of copper is c = 0.385 kJ/kg/K. (a) Assuming ideal gas behavior of the nitrogen, determine the initial mass of nitrogen in the tank, in kg. m_1 =  _______ kg. (b) Determine the final mass. m_2 =  _______ kg. (c) Find the heat transfer to the surroundings from teh tank and its contents, in kJ, ignoring kinetic and potential energy effects. _______ kJ.

An air compressor provides 6700 kW to raise air from an inlet temperature T_1 = 300 K and inlet pressure p_1 = 1 bar to an outlet pressure T_2 = 620 K and outlet pressure p_2 = 12 bar. (a) What is the mass flow rate of air through the compressor, in kg/s? _______ kg/s. The air leaving the compressor flows through a regenerator, where it exchanges heat with a second air stream. The stream leaving the compressor leaves the regenerator at T_3 = 760 K and p_3 = 12 bar. The second air stream enters the regenerator at T_4 = 780 K and p_4 = 1 bar. Its mass flow rate, m_dot_4, is double the mass flow rate of the stream flowing through the compressor. (b) Find the temperature, T_5. Use linear interpolation to obtain an answer that is accurate to 0.1 K. _______ K.

A direct contact heat exchanger (mixer) operates at a fixed pressure of p = p_1 = p_2 = p_3 = 25 bar with a working fluid of water. One stream of water enters at T_1 = 35 deg C and pressure p_1 = 25 bar. A second stream enters at p_2 = 25 bar and a quality x_2 = 0.50. The well-mixed streams leave as a saturated liquid at p_3 = 25 bar. Find the mass flow rate of stream 2. m_dot_2 =  _______ kg/s.

Which option BEST describes what is occurring in the below image of the right renal artery?

What occurs to renal function over time in a patient with polycystic kidney disease (2 points)? How does this affect the ability to measure the kidney (2 points)?

Use the following patient vignette to answer questions 11 – 13. A 35-year-old man presents with a sputum-producing cough and dyspnea at rest. Past medical history is significant for a previous diagnosis of premature emphysema at age 28. The patient denies smoking and excessive alcohol intake or exposure to dust and mold. Family history is significant for coronary artery disease and pulmonary disease in the patient’s father and only brother. Vital signs are within normal limits except for blood pressure of 160/120 mmHg on three readings.  Physical examination reveals an ill-appearing man with prolonged expiratory time. Auscultation of the lungs reveals end-expiratory wheezing. ECG is within normal limits. Which of the following is the most likely risk factor/predisposing condition for this patient’s illness?

Use the following patient vignette to answer questions 1-3. 1.   Mr. Cheeseman is a 55-year-old man. He has been a pack-a-day smoker since the age of 20. He undergoes a pulmonary function test. Which of the following changes are most consistent with his diagnosis of Emphysema? FEV1 FEV1/FVC A. Low High B. Low Low C. High High D. High Low