A refrigerator is operated by a $0.25-\mathrm{hp}(1 \mathrm{hp}$= $746\ watts)$ motor. If the interior is to be maintained at $4.50^{\circ} \mathrm{C}$ and the room temperature on a hot day is $38^{\circ} \mathrm{C}$, what is the maximum heat leak (in $watts$) that can be tolerated? Assume that the coefficient of performance is $50 \%$ of the maximum theoretical value. What happens if the leak is greater than your calculated maximum value?

An axial fan $2 \mathrm{~m}$ in diameter is used in a wind tunnel as shown (test section $1.2 \mathrm{~m}$ in diameter; test section velocity of $60 \mathrm{~m} / \mathrm{s}$ ). The rotational speed of the fan is $1800 \mathrm{rpm}$. Assume the density of the air is constant at $1.2 \mathrm{~kg} / \mathrm{m}^3$. There are negligible losses in the tunnel. The performance curve of the fan is identical to that shown in the mentioned figure. Compute the power needed to operate the fan.

A gas refrigeration cycle with a pressure ratio of 4 uses helium as the working fluid. The temperature of the helium is $-6^{\circ} \mathrm{C}$ at the compressor ind $50^{\circ} \mathrm{C}$ at the turbine inlet. Assuming isentropic efficiencies of 88 percent for both the turbine and the compressor, determine (a) the minimum temperature in the cycle, (b) the coefficient of performance, and (c) the mass flow rate of the helium for a refrigeration rate of 25 kW.

There is a Carnot coefficient of performance $( \mathrm{COP} _{\mathrm{C}})$ for an ideal, or Carnot, refrigerator. (a) Show that this quantity is given by

$$\mathrm{COP}_{\mathrm{C}}=\frac{T_{\mathrm{c}}}{T_{\mathrm{h}}-T_{\mathrm{c}}}$$

(b) What does this tell you about adjusting the temperatures for the maximum COP of a refrigerator? (Can you guess the equation for the $\mathrm{COP} _{\mathrm{C}}$ for a heat pump?)

Consider a 300 kJ/min refrigeration system that operates on an ideal vapor-compression refrigeration cycle with refrigerant-134a as the working fluid. The refrigerant enters the compressor as saturated vapor at 140 kPa and is compressed to 800 kPa. Show the cycle on a T-s diagram with respect to saturation lines, and determine (a) the quality of the refrigerant at the end of the throttling process, (b) the coefficient of performance, and (c) the power input to the compressor.

A refrigeration cycle has a coefficient of performance equal to $75 \%$ of the value for a reversible refrigeration cycle operating between cold and hot reservoirs at $-5^{\circ} \mathrm{C}$ and $40^{\circ} \mathrm{C}$, respectively. For operation at steady state, determine the net power input, in $\mathrm{kW}$ per $\mathrm{kW}$ of cooling, required by (a) the actual refrigeration cycle and (b) the reversible refrigeration cycle. Compare values.

Evaluate the performance of a helical compression spring made from 17-gage ASTM A229 steel wire that has an outside diameter of $0.531\ \mathrm{in}$. It has a free length of $1.25\ \mathrm{in}$, squared and ground ends, and a total of $7.0$ coils. Compute the spring rate and the deflection and stress when carrying $10.0\ \mathrm{lb}$. At this stress level, for what service (light, medium, or severe) would the spring be suitable?

Teletronics reported record profits of $\$ 100,000$ last year and is on track to exceed those profits this year. Teletronics competes in a very competitive market where many of the firms are merging in an attempt to gain competitive advantages. Currently, the company's top manager is compensated with a fixed salary that does not include any performance bonuses. Explain why this manager might nonetheless have a strong incentive to maximize the firm's profits.

The adjusted trial balance of Elmo Real Estate Appraisal at June 30, 2016, follows:

$$\begin{array}{c} \textbf{ELMO REAL ESTATE APPRAISAL}\\ \textbf{Adjusted Trial Balance}\\ \textbf{June 30, 2016}\\ \end{array}$$

$$\begin{array}{lrr} \hline&\textbf{Debit}&\textbf{Credit}\\ \hline\text{Cash}&\$4,900&\\ \text{Accounts Receivable}&4,800&\\ \text{Office Supplies}&2,700&\\ \text{Prepaid Insurance}&1,900&\\ \text{Building}&79,000&\\ \text{Accumulated Dep'n - Building}&&\$26,600\\ \text{Land}&12,600&\\ \text{Accounts Payable}&&19,300\\ \text{Interest Payable}&&8,300\\ \text{Salaries Payable}&&1,700\\ \text{Unearned Revenue}&&800\\ \text{Notes Payable (long-term)}&&42,000\\ \text{Common Stock}&&6,000\\ \text{Retained Earnings}&&37,000\\ \text{Dividends}&27,10&\\ \text{Service Revenue}&&48,400\\ \text{Insurance Expense}&4,000\\ \text{Salaries Expense}&33,900\\ \text{Supplies Expense}&200\\ \text{Interest Expense}&8,300&\\ \text{Utilities Expense}&2,800&\\ \text{Depreciation Expense - Building}&7,900\\ \hline & \$190,100&\$190,100\\ \hline\hline \end{array}$$

Requirements

1. Prepare the company's income statement for the year ended June 30, 2016.
2. Prepare the company's statement of retained earnings for the year ended June 30,
4. Prepare the company's classified balance sheet in report form at June 30, 2016.
5. Journalize the closing entries.
6. Open the T-accounts using the balances from the adjusted trial balance, and post the closing entries to the T-accounts.
7. Prepare the company's post-closing trial balance at June 30, 2016.

A windows air conditioner that consumes of 1 kW of electricity when running and has a coefficient of performance of 3 is placed in the middle of a room and is plugged in. The rate of cooling or heating this air conditioner will provide to the air in the room when running is (a) 3 kJ/s, cooling (b) 1 kJ/s, cooling (c) 0.33 kJ/s, heating (d) 1 kJ/s, heating (e) 3 kJ/s, heating

Suppose that six singers are being lined up to perform at a charity. Call the singers A, B, C, D, E, and F. The order of performance is determined by writing each singer's name on one of six cards, placing the cards in a hat, and then drawing one card at a time. The order in which the cards are drawn determines the order in which the singers perform. Find the probability that

singer B will perform first and singer A will perform last.

A microphone has an unloaded voltage $v_5=20 \mathrm{mV}$, as shown in Figure . An op amp is available as shown in Figure. It is desired to provide an output voltage of $4 \mathrm{~V}$. Design an inverting circuit and a noninverting circuit and contrast the input resistance at terminals $\mathrm{x}-\mathrm{y}$ seen by the microphone. Which configuration would you recommend to achieve good performance in spite of changes in the microphone resistance $R_5$ ?

Which statement best illustrates a negative correlation between the number of hours spent watching TV the week before an exam and the grade on that exam? a. Watching too much television leads to poor exam performance. b. Smart students watch less television. c. Viewing television interferes with a student's ability to prepare for the upcoming exam. d. Students who watch more television perform more poorly on their exams.

Super Markets Inc. is thinking about extending its reach into Scottsdale, Arizona. You are required to give the operational committee of the board of directors an appraisal of the anticipated growth as the director of planning. You must provide facts in your presentation about how much the local populace spends each month on groceries. You should also include information on the connection between income and grocery expenditures. The sample data your helper gathered is listed below.

$$\begin{array}{|ccc|} \hline \text { Household } & \text { Amount Spent } & \text { Monthly Income } \\ \hline 1 & \$ 555 & \$ 4,388 \\ 2 & 489 & 4,558 \\ \vdots & \vdots & \vdots \\ 39 & 1,206 & 9,862 \\ 40 & 1,145 & 9,883 \\ \hline \end{array}$$

Using this, determine the correlation coefficient. Can you conclude that it is greater than 0?