An air-cooled condenser is used to condense isobutane in a binary geothermal power plant. The isobutane is condensed at $85^\circ C$ by air $(c_p = 1.0 kJ/kg \cdot K)$ that enters at $22^\circ C$ at a rate of 18 kg/s. The overall heat transfer coefficient and the surface area for this heat exchanger are $2.4 kW/m^2 \cdot K$ and $1.25 m^2,$ respectively. The outlet temperature of air is (a) $45.4^\circ C$(b) $40.9^\circ C$ (c) $37.5^\circ C$ (d) $34.2^\circ C$ (e) $31.7^\circ C$

A cylinder containing ammonia is fitted with a piston restrained by an external force that is proportional to the cylinder volume squared. Initial conditions are 10$^{\circ} \mathrm{C}$, 90% quality, and a volume of 5 L. A valve on the cylinder is opened and additional ammonia flows into the cylinder until the mass inside has doubled. If at this point the pressure is 1.2 MPa, what is the final temperature?

Saturated vapor R-410a at 60 F in a rigid tank is cooled to 0 F. Find the specific heat transfer.

The carbon monoxide molecule CO has an effective spring constant of 1860 N/m and a bond length of 0.113 nm. Determine four wavelengths of light that CO might absorb in vibration-rotation transitions.

A scientifically untrained but curious friend asks, "When I walk into a room, is there a chance that all the air will be on the other side?" How do you answer this question?

A 2 kg block oscillates with an amplitude of 10 cm on a spring of force constant 120 N/m. (a) In which quantum state is the block? (b) The block has a slight electric charge and drops to a lower energy level by generating a photon. What is the minimum energy decrease possible, and what would be the corresponding fractional change in energy?

At high temperature, the average energy of a classical one-dimensional oscillator is kBT, and for an atom in a monatomic ideal gas, it is $\frac{3}{2} k_{\mathrm{B}} T.$ Explain the difference, using the eqitipartition theorem.

A 1 fs pulse of laser light would be $0.3 \mu m$ long. What is the range of wavelengths in a $0.3 \mu m$ long pulse of (approximately) 600 nm laser light? (1 fs = 10-15 s.)

Carbon (diamond) and silicon have the same covalent crystal structure, yet diamond is transparent while silicon is opaque to visible light. Argue that this should be the case based only on the difference in band gaps— roughly 5 eV for diamond and 1 eV for silicon

How does an engineered cost differ from a discretionary cost?

The Magill Repair Shop repairs and services machine tools. A summary of its costs (by activity) for 2017 is as follows:

$$\begin{matrix} \text{a. Materials and labor for servicing machine tools} & \text{\$ 1.100.000}\\ \text{b. Reword costs} & \text{90.000}\\ \text{c. Expediting costs caused by work delays} & \text{65.000}\\ \text{d. Materials-handling costs} & \text{80.000}\\ \text{e. Materials-procurement and inspection costs} & \text{45.000}\\ \text{f. Preventive maintenance of equipment} & \text{55.000}\\ \text{g. Breakdown maintenance of equipment} & \text{75.000}\\ \end{matrix}$$

1. Classify each cost as value-added, non-value-added, or in the gray area between. 2. For any cost classified in the gray area, assume 60% is value-added and 40% is non-value-added. How much of the total of all seven costs is value-added and how much is non-value-added? 3. Magill is considering the following changes: (a) introducing quality-improvement programs whose net effect will be to reduce rework and expediting costs by 40% and materials and labor costs for servicing machine tools by 5%; (b) working with suppliers to reduce materials-procurement and inspection costs by 20% and materials-handling costs by 30%; and (c) increasing preventive-maintenance costs by 70% to reduce breakdown-maintenance costs by 50%. Calculate the effect of programs (a), (b), and (c) on value-added costs, non-value-added costs, and total costs. Comment briefly.

Describe how the dual-rate method is useful to division managers in decision making.

Chadwick Shoe Co. produces and sells an excellent-quality walking shoe. After production, the shoes are distributed to 20 warehouses around the country. Each warehouse services approximately 100 stores in its region. Chadwick uses an EOQ model to determine the number of pairs of shoes to order for each warehouse from the factory. Annual demand for Warehouse OR2 is approximately 120,000 pairs of shoes. The ordering cost is $250 per order. The annual carrying cost of a pair of shoes is$2.40 per pair. 1. Use the EOQ model to determine the optimal number of pairs of shoes per order. 2. Assume each month consists of approximately 4 weeks. If it takes 1 week to receive an order, at what point should warehouse OR2 reorder shoes? 3. Although OR2’s average weekly demand is 2,500 pairs of shoes 1120,000 , 12 months , 4 weeks 2, demand each week may vary with the following probability distribution: If a store wants shoes and OR2 has none in stock, OR2 can “rush” them to the store at an additional cost of $2 per pair. How much safety stock should Warehouse OR2 hold? How will this affect the reorder point and reorder quantity?$

$$\begin{matrix} \text{Total demand for 1 week} & \text{2,000 pairs} & \text{2,250 pairs} & \text{2,500 pairs} & \text{2,750 pairs} & \text{3,000 pairs}\\ \text{Probability (sums to 1.00)} & \text{0.04} & \text{0.2} & \text{0.52} & \text{0.20} & \text{0.04}\\ \end{matrix}$$

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Steam in a heating system flows through tubes whose outer diameter is 5 cm and whose walls are maintained at a temperature of $180^\circ C.$ Circular aluminum alloy 2024-T6 fins $(k = 186 W/m \cdot K)$ of outer diameter 6 cm and constant thickness 1 mm are attached to the tube. The space between the fins is 3 mm, and thus there are 250 fins per meter length of the tube. Heat is transferred to the surrounding air at $T_{\infty} = 25^\circ C,$ with a heat transfer coefficient of $40 W/m^2 \cdot K.$ Determine the increase in heat transfer from the tube per meter of its length as a result of adding fins.