A solar furnace uses a large parabolic mirror (such mirrors can be several stories high) to focus the light of the Sun to heat a target. A large solar furnace can melt metals. Is it possible to attain temperatures exceeding $6000 \mathrm{~K}$ (the temperature of the photosphere of the Sun) in a solar furnace? If so, how? If not, why not?

$\text{\red{Use Analogies}}$ How is the cell like a furnace?

A small furnace uses $3.00 \mathrm{~kW}$ of power. If the cost of operation of the furnace is $\$ 3.84$ for a $24.0$-h period, find the cost of energy per $\mathrm{kWh}$ .

Classify the following processes as exothermic or endothermic:
(g) heating with a furnace.

How is the air pressure in a tightly sealed house affected by operating the furnace? Explain.

A 3-m-diameter spherical furnace contains a mixture of $CO_2$ and $N_2$ gases at 1200 K and 1 atm. The mole fraction of $CO_2$ in the mixture is 0.15. If the furnace wall is black and its temperature is to be maintained at 600 K, determine the net rate of radiation heat transfer between the gas mixture and the furnace walls.

Explain the differences among -blast, -cyte, and -clast cells of connective tissue.

The walls of a furnace are made of $1.2-\mathrm{ft}$-thick concrete $\left(k=0.64 \mathrm{~Btu} / \mathrm{h} \cdot \mathrm{ft} \cdot{ }^{\circ} \mathrm{F}\right.$ and $\left.\alpha=0.023 \mathrm{~ft}^{2} / \mathrm{h}\right)$. Initially, the furnace and the surrounding air are in thermal equilibrium at $70^{\circ} \mathrm{F}$. The furnace is then fired, and the inner surfaces of the furnace are subjected to hot gases at $1800^{\circ} \mathrm{F}$ with a very large heat transfer coefficient. Find how long it will take for the temperature of the outer surface of the furnace walls to rise to $70.1^{\circ} \mathrm{F}$.

Surface Combustion, Inc., calculates the cost of manufacturing a particular furnace to be $1214.78. Surface marks up each furnace 120% based on cost. What is the selling price?

Consider a 4-m× 4-m× 4-m cubical furnace whose floor and ceiling are black and whose side surfaces are reradiating. The floor and the ceiling of the furnace are maintained at temperatures of 550 K and 1100 K, respectively. Determine the net rate of radiation heat transfer between the floor and the ceiling of the furnace.

The following reactions all occur in a blast furnace. Which of these are redox reactions? (a) $3 \mathrm{Fe}_2 \mathrm{O}_3(s)+\mathrm{CO}(\mathrm{g}) \longrightarrow 2 \mathrm{Fe}_3 \mathrm{O}_4(s)+\mathrm{CO}_2(\mathrm{~g})$ (b) $\mathrm{Fe}_3 \mathrm{O}_4(s)+\mathrm{CO}(\mathrm{g}) \longrightarrow 3 \mathrm{FeO}(s)+\mathrm{CO}_2(g)$ (c) $\mathrm{FeO}(s)+\mathrm{CO}(\mathrm{g}) \longrightarrow \mathrm{Fe}(l)+\mathrm{CO}_2(\mathrm{~s})$ (d) $\mathrm{C}(\mathrm{s})+\mathrm{O}_2(\mathrm{~g}) \longrightarrow \mathrm{CO}_2(\mathrm{~g})$ (e) $\mathrm{C}(\mathrm{s})+\mathrm{CO}_2(\mathrm{~g}) \longrightarrow 2 \mathrm{CO}(\mathrm{g})$ (f) $\mathrm{CaCO}_3(\mathrm{~s}) \longrightarrow \mathrm{CaO}(\mathrm{s})+\mathrm{CO}_2(\mathrm{~g})$ (g) $\mathrm{CaO}(s)+\mathrm{SiO}_2(s) \longrightarrow \mathrm{CaSiO}_3(l)$

Consider a homeowner who is replacing his $25$-yearold natural gas furnace that has an efficiency of $55$ percent. The homeowner is considering a conventional furnace that has an efficiency of $82$ percent and costs $\$ 1600$ and a highefficiency furnace that has an efficiency of $95$ percent and costs $\$2700$. The homeowner would like to buy the high efficiency furnace if the savings from the natural gas pay for the additional cost in less than $8$ years. If the homeowner presently pays $\$ 1200$ a year for heating, Find if he should buy the conventional or high-efficiency model.

The London "bobby" whistle has a frequency of $2500 \mathrm{~Hz}$. If such a whistle is given a $3.0$ s blast, (a) what is the uncertainty in the frequency? (b) How long is the wave train of this blast? $(c)$ What would be the uncertainty in measuring the wavelength of this blast? (d) What is the wavelength of this blast?

Product K has a unit contribution margin of $120. Product L has a unit contribution margin of$100. Product K requires five furnace hours, while Product L requires four furnace hours. Determine the most profitable product, assuming that the furnace is a production bottleneck.