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Chapter: 31 -Problem: 21 >> Estimate the total power of the Gulf Stream in the Florida Straits, given that the mass flux is roughly 30 Sv. Take the speed of the flow to be 4 m/s.
Answer Preview: The mass flux is given by t…

, Chapter: 31 -Problem: 18 >> Consider a tidal barrage constructed to enclose a lagoon of surface area 5 km2, with typical tidal range of 4 m. What is the maximum possible average power output of such a barrage? How much would the net output be increased if an additional 1 m of water were pumped in at every high tide and pumped out at every low tide? (Remember to subtract energy used for pumping.)
Answer Preview: The total energy contained in water in the lagoon …

, Chapter: 35 -Problem: 3 >> Data are available on the location of coastlines on several continents during the Pliocene era when temperatures were at levels projected to be reached over the next century. Locate data on a region of interest to you and consider some of the implications.
Answer Preview: Since 1880, average global temperatures have increased by a…

, Chapter: 30 -Problem: 8 >> The axial-momentum theory approximation to blade design breaks down when r/R becomes too small. Use eqs. (30.11) and (30.15)  to show that the condition KB < 2?r limits the angle ? to sin ? tan ? < cl (1 ? a)/(4a). For the choice of parameters in Figure 30.10  what is the smallest value of r/R allowed by this condition? Tr
Answer Preview: From eq 30 15 and from eq 30 11 r v 1a tan Su…

, Chapter: 29 -Problem: 1 >> Angel Falls in Venezuela, at a height of 979 m, is the highest waterfall in the world. Ignoring air resistance, how much warmer is the water at the bottom of the falls, where the kinetic energy it acquired by falling has been dissipated as heat, than it was at the top?
Answer Preview: From Example 29 1 T v 2 2c Falling 979 m gives the water a velocity of …

, Chapter: 31 -Problem: 11 >> Derive the statements made about the power density of 1 m and 10 m deep ocean swells in §31.2.4.
Answer Preview: The statement in 31 2 4 states that the power density of 1 m deep ocean swells is lower than …

, Chapter: 32 -Problem: 11 >> Consider the efficiency computed in the example single-flash cycle in Example 32.5. Use thermodynamic data on water to show that running the separator at T = 140 ?C or T = 160 ?C will decrease the efficiency of the ideal cycle.
Answer Preview: The necessary thermodynamic data for water in addition to the data given i…

, Chapter: 27 -Problem: 1 >> The absorption coefficient of water for light of wavelength 450 nm is roughly ?450 ? 0.0001 cm?1 while for light of wavelength 750 nm it is roughly ?750 ? 0.03 cm?1. Estimate the depth by which 90% of light has been absorbed by the ocean in each of these wavelength ranges. Explain the color seen underwater at typical depths encountered by divers.
Answer Preview: From the question we know that absorption coefficient of …

, Chapter: 24 -Problem: 6 >> Consider a flat-plate collector covered by a single pane of glass exposed to perpendicular insolation at 1000 W/m2. The collector operates at a net efficiency of 35% at a temperature Tb ? 65 ?C. Assuming that the glass covering stays at the ambient temperature of 15 ?C, compute the net power radiated and non-radiative losses for the collector. Ignore incident infrared light from the atmosphere.
Answer Preview: In the absence of non radiative losses 1 T …

, Chapter: 29 -Problem: 3 >> What is the Magnus effect and what does it have to do with the phenomenon of lift?
Answer Preview: Magnus effect is the effect usually seen in spinning objects like balls …

, Chapter: 29 -Problem: 4 >> Supply the missing steps in the derivation of the expression for the flow rate Q in a Venturi flow meter in Example 29.2.
Answer Preview: Start with Bernoullis law as written in the …

, Chapter: 38 -Problem: 2 >> Some utilities charge customers for the apparent power delivered (i.e. including reactive power) rather than real power consumed. Discuss the possible justifications for this.
Answer Preview: Electric power has two components: 1. Active Power 2. Reactive Power The total power (S) is called apparent power and is given by the product of Volta…

, Chapter: 32 -Problem: 13 >> Estimate the energy extracted from 1 km3 of granite if cooled from 300 ?C to 200 ?C. Assume that a power plant runs between the (time-varying) temperature Tg of the granite and an ambient temperature of 20 ?C and reaches 1/2 of the Carnot efficiency at each Tg. For how long could a 100 MW power plant run off this energy?
Answer Preview: For granite c p 790 J kg K and 2 7 10 3 kg m 3 The total thermal ene…

, Chapter: 34 -Problem: 1 >> The term inversion describes a weather event in which the lapse rate near the ground is negative – the temperature actually increases with height. Explain why inversions are often associated with episodes of severe air pollution and are also responsible for the phenomenon of freezing rain in the winter.
Answer Preview: Under normal conditions in the earth's lower atmosphere (troposphere), the lapse rate demonstrates that temperature decreases with height. This is bec…

, Chapter: 22 -Problem: 10 >> Rewrite the black body power spectrum as a function of ? and compute the value ?max?where the power density dP/d? is maximized. Find the frequency ? corresponding to ?max. Why is ? not equal to ?max, where ?max is given by eq. (22.14) ? Compare ?max?to 2?c/?max for a black body at temperature 5780 K. Transcribed Image Tex
Answer Preview: The black body power spectrum is Letting 2c The si…

, Chapter: 31 -Problem: 13 >> Imagine that Earth rotated about its axis once per month and that the Moon moved in a circular orbit above Earth’s equator. Under these tidally locked conditions, the Moon and the resulting tidal bulge in Earth’s oceans would remain fixed in an Earth-based reference system. Give an estimate of the tidal displacement in this situation by computing the gravitational potential along a line passing th
Answer Preview: Use the notation of eq 31 25 The gravitational potential at a point on Earths …

, Chapter: 33 -Problem: 3 >> Investigate the production of helium. How was it formed? Why is it found in natural gas? How much of it is recovered? Discuss conservation of the world’s helium resources.
Answer Preview: Helium cannot produced by chemical way .it is generally produced by sl…

, Chapter: 20 -Problem: 18 >> Particle physics experiments are shielded from cosmic ray muons by placement underground, often in old mines. Cosmic ray muons have been detected at 2000 feet below ground at the Home stake Gold Mine in South Dakota. Estimate a lower limit on the energy of these muons when created high in the atmosphere.
Answer Preview: 2000 ft 600 m S 2 MeV cm 2 gm and the mean density of …

, Chapter: 31 -Problem: 2 >> Compare land use of hydropower to solar power by computing the ratio of power output to reservoir surface area for the Three Gorges Dam (maximum capacity 22500 MW, reservoir area 1084 km2) and the Hoover Dam (maximum capacity 2080 MW, reservoir area 680 km2), and comparing to the power density of a typical large-scale solar thermal or solar photovoltaic power plant in the desert.
Answer Preview: Defining power density per unit area as power capacity divided by reservoir size we fin…

, Chapter: 36 -Problem: 2 >> Consider a system 1 where a container is divided into two parts by an impermeable membrane. The two equal-size parts contain nitrogen and oxygen gases at the same pressure and temperature. The membrane is removed and the gases are allowed to mix, giving a system 2 in thermodynamic equilibrium. Describe the change in` energy between system 1 and 2. What does this mean about how much useful work cou
Answer Preview: The change in energy between system 1 and 2 is the decrease in internal energy of the system. …

, Chapter: 17 -Problem: 10 >> Derive eq. (17.20) ?by differentiating the SEMF expression for b(Z, A) with respect to Z at fixed A.? Transcribed Image Text: A/2 1+7.52 x 10-3 A²/3 A/2 Zmin (A) 1+CA2/3 4E sym
Answer Preview: Only the Z dependent terms in bZ A are …

, Chapter: 27 -Problem: 8 >> Compare the gravitational force and horizontal Coriolis force on a person running at 6 m/s at latitude 45?. How fast would an object have to be moving for the two to be equal?
Answer Preview: g 9 8 m s 2 whereas a c v 2 v sin With 4 and …

, Chapter: 36 -Problem: 3 >> Consider the power/power density ratio 105 m2 for the “zero dimensional” hydro resource in the figure in Box 36.3, compared to the “1D” waves resource (107m2) and the “2D” solar resource (107m)2. Try to explain the relative ratio in the hydro case using the scale of a typical hydro power installation (which is very small compared to the terrestrial length scale) and a rough estimate of the number
Answer Preview: The power/power density ratio of 105 m2 for the zero dimensi…

, Chapter: 17 -Problem: 17 >> Examine the derivation of Gamow’s formula for ?-decay lifetimes, and then derive the equivalent expression for decay by emission of a (small) nucleus of charge z and mass number a. Assume a/A is small enough to ignore recoil. Make sure that the z and a dependence are explicit. Compare your result to an?-decay lifetime with the same Q-value.
Answer Preview: General form of Gamows formula …

, Chapter: 31 -Problem: 12 >> In the JONSWAP model, the energy transferred to the moving ocean surface waters is proportional to the distance over which wind travels (fetch, F). For a steady wind at 10 m/s compute the rate of energy transfer per unit area to the ocean’s surface. What fraction of the energy of the wind in the 100 meters over the ocean’s surface is transferred to the ocean with a fetch of 200 km?
Answer Preview: According to the equation for the energy density E in Box 31 3 dE dF 1 67 …

, Chapter: 32 -Problem: 1 >> Find out how the Kalina cycle works and discuss its application to geothermal power. To what kind of resources is it best suited?
Answer Preview: The Kalina cycle, named after the Russian engineer Alexander Kalina , is a thermodynamic cycle for converting thermal energy to mechanical power. The …

, Chapter: 21 -Problem: 9 >> Consider the circumstances described in Problem 21.8, but now suppose that ?2 < 0. Use the transformation defined in Problem 21.7 to show that there is a reference frame traveling at a speed v < c in which the two events occur at the same place, but different times. Show that the time order of the events is the same in all reference frames related by the transformation of Problem 21.7. In this cas
Answer Preview: The space separation between the events as seen by observer 2 is and this can be made to vanish …

, Chapter: 24 -Problem: 13 >> For the power tower geometry from the previous problem, assume that the absorber height is equal to its diameter, and that the diameter is that found in part (b) above. If all the light from an overhead sun that hits the circle of radius 100 m containing the reflecting mirrors were to be reflected to the absorber, what would be the effective concentration of the mirror configuration as a solar con
Answer Preview: Let the diameter of the absorber be d and the radius of the array be R then …

, Chapter: 25 -Problem: 5 >> Given four materials, with band gaps 0.2 eV, 0.7 eV, 1.5 eV, and 3 eV, which two are likely to make the best double-junction solar cell? Explain your answer.
Answer Preview: In the double junction solar cell: The two junctions ca…

, Chapter: 18 -Problem: 15 >> Show that the probability of finding a particle with energy greater than 0.2 MeV in a gas at temperature 15 × 106 K is ?10?69.
Answer Preview: We need the probability of finding a particle with energy greater tha…

, Chapter: 27 -Problem: 4 >> Under the same assumptions as for Problem 27.3, estimate the net rate at which energy is lost to upward thermal radiation. First, compute the rate of upward thermal radiation. Then include a downward IR radiation flux, approximated by thermal radiation from the atmosphere at an altitude of 2000 m at 20 ?C, and compute the net upward energy flux.
Answer Preview: The question addresses thermal radiation alone …

, Chapter: 22 -Problem: 9 >> Show that the peak of the black body spectrum as a function of ? is given by eq. (22.14) Transcribed Image Text: kg T Wmax = 2.82
Answer Preview: The peak wavelength of the black body spectrum …

, Chapter: 27 -Problem: 6 >> Given Earth’s radius, mass, and rate of rotation, estimate the difference in radius measured along the equator from that measured to a pole in order that the apparent gravitational potential is the same everywhere on Earth’s surface by approximating the gravitational  potential as that of a spherical Earth plus a correction term due to centrifugal force. Compare your answer to the actual differenc
Answer Preview: The corrected potential is where r is distance from center and is dis…

, Chapter: 26 -Problem: 4 >> The fossil fuel energy input currently needed for ammonia production is roughly 36 GJ/t (§33.3.4). Estimate the energy needed to produce ammonia containing 90 Mt of nitrogen. Compare to the biomass energy of 18 EJ in 40% of all food crops that is estimated to be enabled through fertilizer inputs.
Answer Preview: Ammonia NH 3 is 14 17 82 nitrogen so 90 Mt of nitrogen fixed …

, Chapter: 34 -Problem: 2 >> Hydrogen and helium are the two most common elements in the universe. What are their concentrations in Earth's atmosphere? Why are they so rare?
Answer Preview: The concentrations of hydrogen and helium in earths atmosphere is Gas Name Chemical Formula Percent …

, Chapter: 31 -Problem: 6 >> Use dimensional analysis to determine the dispersion relation ?(k) for surface tension waves (up to a multiplicative constant), which can only depend on the surface tension ?, the density ?, and the wave number k. Find the phase velocity and the group velocity, and show that vg = 3vp/2. Describe how you could distinguish visually between gravity waves and surface waves by observing the way that in
Answer Preview: By dimensional analysis v g d dk 3 2k 3v p 2 Since v …

, Chapter: 36 -Problem: 7 >> What is the energy of sunlight (in units of W/m2 at normal incidence)? Discuss how energy is destroyed when sunlight is converted to electricity by photo voltaic cells, by solar thermal electric power plants, and by direct burning of biomass.
Answer Preview: Hounal power plant having efficiency of 35% to 45% Biomass having efficiency of 20% to 25% Energy …

, Chapter: 28 -Problem: 8 >> Suppose the wind speed obeys a Gaussian frequency distribution in the two components of the horizontal velocity v = (v1, v2), Show that the wind speed distribution, f (v) = dP/dv, Where? is a Rayleigh distribution (Weibull parameter k = 2). What is the scale ?? Distribution The word "distribution" has several meanings in the financial world, most of them pertaining to
Answer Preview: The Weibull distribution is a distribution in wi…

, Chapter: 33 -Problem: 4 >> Estimate the relative carbon output of heating a home using (a) natural gas, (b) electrical heating powered by electricity from coal-fired power plants. How much do your assumptions about what technology is used affect your answer?
Answer Preview: about 0 85 pounds In 2020, total U S. electricity generation by the electric power …

, Chapter: 32 -Problem: 9 >> For a geothermal well that has been running for some time, pressure at the bottom of the well is pw ? 15MPa at a depth of 2 km. Assume the fluid is water at 280 ?C. Estimate the location of the flash horizon. (You may neglect the contribution to the pressure from the weight of the vapor above the flash horizon.)
Answer Preview: The density and vapor pressure of water at 280 C are 750 kg m 3 and p vap 6 4…

, Chapter: 25 -Problem: 15 >> An actual solar cell has internal resistances that affect the behavior of the circuit. These can be modeled as a single shunt resistance Rp in parallel with the diode, and another resistance Rs in series with the external load. Derive the modified ideal diode equation in the presence of the resistances.
Answer Preview: The actual solar cell model is given by …

, Chapter: 30 -Problem: 1 >> A variable-speed HAWT has a power coefficient of 0.45 at its rated wind speed vr and maintains its rated power for wind speeds between this value and its cutout speed of 25 m/s. If the rotor diameter is 100 m, and the rated power is 3 MW, what is vr?
Answer Preview: According …

, Chapter: 25 -Problem: 18 >> The absorption coefficient of silicon has a strong dependence on photon energy, as shown in Figure 25.16 For simplicity, consider an idealized material, material S, similar to crystalline silicon, with an absorption coefficient of ? = 7?103 m?1 for light at any wavelength. What fraction of (normally incident) light will be absorbed by a wafer of material S that is 200 ?m thick? If we could fabri
Answer Preview: Absorption coefficient of crystalline si…

, Chapter: 29 -Problem: 6 >> The maximum takeoff mass for a Boeing 777-300ER passenger jet is 3.5 × 105 kg. The plane’s wing area is about 440 m2. Compute the average air pressure on the plane’s wings required to overcome the plane’s weight and lift the plane off the ground. How far does this pressure deviate from average atmospheric pressure at sea level? Repeat the calculation for a Lear jet with mass 3300 kg and wing area
Answer Preview: Pressure is force per unit area The force of gravity can …

, Chapter: 24 -Problem: 4 >> Consider an idealized flat-plate solar collector. Assume that there are no heat losses to conduction or convection. Assume that the insolation is 1000 W/m2 incident at an angle of 45? from the vertical. Compute the temperature of the black body in radiative equilibrium assuming that (a) The collector is horizontal, (b) The collector is tilted at 35? towards the Sun.
Answer Preview: a The intensity at normal incidence is I 0 1000 W m 2 and so the insolation on a collec…

, Chapter: 32 -Problem: 10 >> Assume that enthalpy is a linear function h(s, T) = as + bT. Consider a single-flash cycle, assuming that the saturated liquid and vapor curves between T? and T+?form an isosceles trapezoid, i.e. Prove that the optimal separator temperature is Transcribed Image Text: Sliquid (T+) – Sliquid (T – )
Answer Preview: We begin by writing the enthalpy expression as a function of temperature: h(…

, Chapter: 26 -Problem: 5 >> If all land area in the US that is used for growing corn for ethanol were used for solar thermal electric plants operating at a gross conversion efficiency of 3%, estimate the total electrical energy yearly produced assuming an average insolation of 200 W/m2. Compare to US energy consumption of roughly 100 EJ, assuming 35% efficiency for 65 EJ of petroleum and coal energy used and 100% efficiency
Answer Preview: According to Box 26 5 about 15 10 6 ha or 1 5 10 11 m 2 are used to grow corn ethanol If …

, Chapter: 29 -Problem: 2 >> Aspirator pumps are used in many applications, ranging from emptying fish tanks to providing vacuum for industrial processes. How do they work?
Answer Preview: Aspirator pumps work on the principle of Bernoulli\'s equation. That is given by; P+dgh+(1/2)dv**2…

, Chapter: 32 -Problem: 3 >> Check eq. (32.4) by estimating the radioactive heat production rate using data from Table 20.6 Take the fractional abundances of 235U, 40K to be 0.72%, 0.012%. Take the average energy release in 40K decay to be 0.71MeV. Transcribed Image Text: O = 98CU + 26.5CTH + 0.0035Ck[µW/kg] Half-life (y) Init
Answer Preview: The power emitted by N j atoms of a radioactive isotope j with half life t …

, Chapter: 27 -Problem: 1 >> The Coriolis force determines the directions of the trade winds, mid latitude Westerlies, and Polar Easterlies as described in the text. What about the strength of these winds? How, for example, should the trade winds behave as one approaches the Equator? How should the mid-latitude Westerlies in the Southern Hemisphere vary with latitude? Do your speculations agree with observations?
Answer Preview: The strength of the trade winds, mid-latitude Westerli…

, Chapter: 28 -Problem: 7 >> What is the maximum power that could be extracted by a mechanical device of cross-sectional area 10 m2 in a steady wind at 10 m/s?
Answer Preview: We will use the air density at STP 1 2…

, Chapter: 36 -Problem: 4 >> Investigate vacuum tube trains as an efficient, low-carbon transportation option. To what extent could they use gravity to accelerate/decelerate? Where would such train lines make sense Would they be practical for transport of materials or only for people? What are some of the pros and cons of such a transportation system?
Answer Preview: Vacuum tube train or vactrain is a proposed design for very-high-speed rail transportation. It is a …

, Chapter: 28 -Problem: 14 >> Use the data given in the wind rose Figure 28.19 To make a crude estimate of the average ?v? and root mean cube v? wind speed at Klamath Lake, Oregon. From these, estimate the Weibull parameters for this distribution. Is your result close to a Rayleigh distribution (k = 2)? Is this a promising wind power location? Distribution The word "distribution" has several meanings
Answer Preview: Taking values of v in the middle of listed ranges and ignoring the very small contribution from v …

, Chapter: 25 -Problem: 17 >> The thickness of the germanium (density 5.32 gm/c m 3) layer in a triple-junction PV is typically greater than 100 microns. If the overall cell efficiency is 40%, how many watts of PV capacity (nominal insolation of 1000 W/m2) could be manufactured from the world’s annual germanium production (165 t in 2014)?
Answer Preview: Each square meter of germanium at 100m thickness requires …

, Chapter: 24 -Problem: 16 >> Consider a linear 2D compound parabolic concentrator built from parabolas tilted at 10? to the vertical, with a trough of width 3 m, and an absorber width of 0.5 m. Compute the concentration C of the concentrator. If the incoming radiation has intensity I0 = 1000 W/m2 and the (blackbody) absorber is kept at a temperature of 100 ?C by circulation of a thermal fluid, compute the rate of energy trans
Answer Preview: The concentration of the compound parabolic concentrator is given by: C = 4I0 / ( * w * h) where w i…

, Chapter: 32 -Problem: 8 >> Given a geothermal reservoir containing water at temperature T = 200 ?C at a depth of 1.5 km, use steam tables to determine the density and vapor pressure of the water. Assuming that pressure in the wellbore decreases according to the overlying weight of water, at what well pressure Pw will the flash occur in the wellbore?
Answer Preview: The density and vapor pressure of water at 200 C are 864 kg m 3 an…

, Chapter: 29 -Problem: 4 >> There are many flawed “elementary explanations” of lift. One (mentioned in §29.4) is based on the idea that air takes an equal time to pass above and below an airfoil. What is the argument? What is wrong with it?
Answer Preview: The lifting of airfoil is primarily based on Bernoulli's equation. The time taken by the air on upp…

, Chapter: 17 -Problem: 23 >> In light of the results of Problem 17.22, what is the rate of energy emission (J/kg) of a sample of 238U that has been around long enough to come into decay equilibrium?
Answer Preview: Since all decays contribute equally in equilibrium Problem 1722 the entire decay c…

, Chapter: 29 -Problem: 14 >> A modern medium size commercial jet plane has a wing span of L = 30 m and a mean chord length of K = 4 m. Its lift coefficient is cl = 0.83 at its cruising angle of attack ? ? 2?. What is the lift force generated by the airplane wings when cruising at v ? 800 km/h? While cruising, the engines exert a thrust of ?80 kN. Estimate the wings’ drag coefficient cd and the lift to drag ratio.
Answer Preview: From eq 29 32 and taking the density of air to be 1 17 kg m 3 …

, Chapter: 38 -Problem: 4 >> Make a list of the properties that you would expect to characterize a liquid used as a transformer coolant. Investigate: what was the dominant coolant used prior to the 1970 s? Why was its use discontinued, and what coolants are used now?
Answer Preview: The properties of transformer coolant are: Electrical properties: Dielectric strength, specific resi…

, Chapter: 17 -Problem: 19 >> Verify the expressions for the Q-value in ??-decay and electron capture, eq. (17.34)? Transcribed Image Text: Q(B¯) = A(Z, A) – A(Z + 1, A), Q(B+) = A(Z, A) – A(Z – 1, A) – 2Ae Q(EC) = A(Z, A) - A(Z – 1, A),
Answer Preview: For decay eq 1732 gives adding and subtrac…

, Chapter: 29 -Problem: 11 >> Suppose that in a region of steady flow the velocity of a fluid is given by v =  ? × r, where r is the vector from a fixed point in space. Describe the streamlines of this flow. Show that ? · v = 0, so this flow is consistent with the fluid being incompressible. Compute the circulation ? on a circle of radius R about the center of the flow. Show that the fluid is rotating with angular velocity and
Answer Preview: Let define the z axis Then where we have used x y z etc The …

, Chapter: 18 -Problem: 9 >> Two sources of delayed neutrons in 235U fission are the fission fragments 87Br and 137I. Find the fraction of their decays that yield a neutron, and the half-life of each. Verify that the Q-value for the ?-decay with neutron emission is positive.
Answer Preview: From 70 87 Br has a halflife of 5565 s and yields a neutron 26 of th…

, Chapter: 23 -Problem: 5 >> Suppose a gas has an absorption cross section per molecule ?(?) for light of frequency ? (see §18.2 for an introduction to cross sections). Show that the gas’s absorption coefficient is given by ?(?) =?(?)?, where ? is the number density of gas molecules.
Answer Preview: Consider photons are traveling through a tube of cross sectional …

, Chapter: 17 -Problem: 20 >> Ignoring small electron binding energies and the very small mass of the neutrino, show that the mass of a nucleus increases when it decays by electron capture if the Q-value of the decay is less than mec2 ? 0.511 MeV. Verify that this is the case for the electron capture decay of the longest-lived isotope of technetium: T
Answer Preview: When a nucleus A Z decays to A1 Z 1 by electron captureenergy conservation gives where we have ig…

, Chapter: 33 -Problem: 1 >> Estimate the energy content of a coal seam measuring 1 km2 by 1 m deep. Estimate the electrical power output of a coal plant burning this fuel over one year, and the area required for a solar thermal plant in a high insolation location to produce a comparable power output. Take the density of coal to be ? = 1300 kg/m3.
Answer Preview: Assume that the energy content of the coal is 20 GJ t The energy content of the coal is At …

, Chapter: 22 -Problem: 4 >> The incandescent light bulb is a notoriously inefficient way to convert electric power into visible light. The tungsten filament emits blackbody radiation at a temperature that is limited by its melting point. Define the lighting efficiency as the ratio of the power emitted in the visible range (400–750 nm) to the total power emitted. What is the theoretical maximum efficiency of a tungsten light
Answer Preview: Following the same steps as in Problem 221 we need …

, Chapter: 31 -Problem: 7 >> Consider a deep-water wave with amplitude a = 1 m and period 12 s. Compute the energy density and power. When the wave moves into shallow water, what is the height and energy density of the wave at 2 m and at 1 m depth?
Answer Preview: The energy density of the deep water wave is and the power is eq 31 20 When the wave move…

, Chapter: 17 -Problem: 21 >> 97% of naturally occurring calcium is calcium-40,4020Ca. This may seem surprising, since if we use the semi-empirical mass formula to estimate the most stable nuclide with A = 40 we find Z ? 18. This suggests that 4020Ca might be unstable to electron capture, which would increase its N/Z ratio. Show that 4020Ca cannot electron capture to 4019K. Show, however, that it is possible for 4020Ca to capt
Answer Preview: For 40 20 Ca electron capture to 40 19 K so this decay is …

, Chapter: 28 -Problem: 5 >> The wind speed at any site can be written as the sum of its average ?v? plus a fluctuating term that averages to zero, v(t) = ?v? + ?v(t). Show that the effect of the fluctuations is always to make ?v3? greater than ?v?3.
Answer Preview: Substitute the decompos…

, Chapter: 19 -Problem: 6 >> An approximate description of the Oklo uranium deposit is 90% uraninite (UO2) by mass, saturated with water that acted as the moderator. Assume that the Oklo deposit was homogeneously saturated with water with a ratio of 3.5 uranium nuclei per water molecule and compute the minimum enrichment (235U/238U) needed to sustain a fission reaction. You can ignore the moderating effect of the extra oxygen
Answer Preview: The question reduces to what is the minimum value of enrichment x for a water moderated rea…

, Chapter: 30 -Problem: 6 >> Derive eq. (30.15) by equating the normal force per unit length on a blade element given in eq. (30.12) with the thrust per unit length obtained from the axial momentum analysis (30.14). Transcribed Image Text: 8?? K sin o Àc B pOK Bu2(1 – a)²c ST =-K Bu q sino 2 2, 2 sin o oK Bu²(1 – a)²cj cos o S
Answer Preview: Equating the two expressions for f …

, Chapter: 17 -Problem: 24 >> The uranium isotope 234U accounts for 0.0054% of naturally occurring uranium. Its half-life ?1/2 (234U) =2.455 × 105 y is much too short for any primordial 234U to still exist on Earth. Explain why 234U occurs naturally and explain its fractional abundance. Use the result of Problem 17.22.
Answer Preview: Assuming that the uranium has been in place long enough to achi…

, Chapter: 29 -Problem: 7 >> Show that for the flow of a viscous fluid through a pipe, as analyzed in Box 29.1, the energy per unit mass dissipated as thermal energy by viscous forces is dQ/dm = ?p/?, where ?p is the pressure difference between the ends of the pipe. The answer is independent of the viscosity and the cross-sectional shape of the pipe. Suppose water is forced through a pipe by a pressure difference of 10 atm. H
Answer Preview: Use conservation of energy in a fashion similar to the derivation o…

, Chapter: 20 -Problem: 13 >> 131I is a dangerous fission product because iodine is preferentially absorbed by the thyroid gland in children. It has a half-life of about 8 days and emits a ?-particle with average energy 180 keV. (Ignore the?-radiation that accompanies this decay (see Example 20.2.)) How much mass of 131I (per gram of thyroid tissue) must a child absorb to suffer an equivalent dose of 10 mSv to the thyroid? Wha
Answer Preview: With a radiation weighting factor of one for particles …

, Chapter: 28 -Problem: 13 >> Reference [192] studies wind power prospects for several locations in Saudi Arabia, among them Yenbu (Y) and Al Qaysumah (A). They report Weibull parameters measured at a height of 10 m: ?Y ? 5.9 m/s, kY ? 2.25; ?A ? 5.1m/s, kA ? 4.38. Estimate the maximum available wind power density and the wind power class for each site at a height of 80 m assuming a roughness length z0 ? 2 × 10?5 (sand). Can y
Answer Preview: First the wind speeds must be scaled from 10 m to 80 m Since sets the scale for the wind speed The p…

, Chapter: 20 -Problem: 15 >> According to the text, roughly 10–15% of lung cancer deaths in the US are due to radon exposure. Use the LNT model and average yearly effective dose from radon to estimate the cancer rate from this source.
Answer Preview: The annual average effective dose from radon exposure in the US is …

, Chapter: 29 -Problem: 9 >> A large wind turbine blade is 50 m long and has a maximum chord length of 4 m at a point one-third of the way out from the wind turbine hub. When rotating at its design rate, the blade sees an air stream moving at 100 m/s at the blade tip. What is the Reynold’s number of the air flow at the point of maximum chord length? Suppose the aerodynamic properties of the blade are to be studied in a wind t
Answer Preview: To study the properties of the blade the Reynolds number must be the …

, Chapter: 17 -Problem: 9 >> Find the SEMF prediction for Zmin(A = 200) from eq. (17.20) Find the actual value of Z that gives the greatest binding energy for A = 200. How well does the SEMF do?? Transcribed Image Text: A/2 1+7.52 x 10-3 A²/3 A/2 Zmin (A) 1+CA2/3 4E sym
Answer Preview: According to eq 1720 so the SEMF predicts that the …

, Chapter: 27 -Problem: 12 >> Derive the relation du/dt = d?u/dt + ? × u by an explicit computation in a coordinate system where ? = ?z? as described in Box 27.1.
Answer Preview: Define the coordinate directions x and y as in Examp…

, Chapter: 18 -Problem: 1 >> Suppose a beam of particles with flux ? is incident on a uniform target of thickness T and density ?(mass/volume). Assuming that the atoms in the target do not block one another (the thin-target approximation),show that the reaction rate dN/dt is given by dN/dt = I??NAT/m, where I is the beam current (i.e.,the integral of the flux over the area of the beam), mis the molecular mass of the target, N
Answer Preview: According to eq 181 dNdt TOT where TOT here is the cr…

, Chapter: 29 -Problem: 13 >> Investigate the location of the stagnation points for fluid flow around a cylinder as described in §29.4.1. Show that for small ? there are two stagnation points on the cylinder and find their location. What is the critical value of ?/Rv? for which there is only one stagnation point? For larger values of ? are there stagnation points in the flow? If so, where are they?
Answer Preview: Express the components of the velocity field of eq 29 28 In terms of the polar c…

, Chapter: 18 -Problem: 21 >> Tritium is just barely unstable. How much more tightly would tritium have to be bound in order for it to bestable? Write the nuclear reaction describing tt fusion.How much energy is emitted in tt fusion? Unfortunately the cross section for tt fusion is much smaller than that for dt fusion, so even if tritium were stable, tt fusion would not be an interesting candidate for fusion power.
Answer Preview: The Qvalue for tritium decay is Q 3 H 3 He 149498 149312 00186 …

, Chapter: 16 -Problem: 1 >> Investigate the proposed mechanisms for recovering uranium from seawater. What do you think are the prospects for this source of uranium?
Answer Preview: There are more than 4 billion metric tons of Uranium deposits in the Earth s oceans The Uranium conc…

, Chapter: 26 -Problem: 7 >> Compute the maximum energy content of the ethanol produced from corn farmed at 10 t/ha y, assuming that the corn is 70% starch composed of polysaccharides (amylose and amylopectin) built from glucose (glucan) units of molar mass 162 g/mol.
Answer Preview: Each glucose unit produces two molecules of ethanol …

, Chapter: 20 -Problem: 22 >> Consider a situation in which, through accident or ill-intention, all the spent nuclear fuel from a year’s operation of a 1 GWe light water reactor were uniformly distributed across one square kilometer of land 1000 years after the waste is sequestered. Using the information in the chapter, estimate the radiation exposure in Sv/year to an unprotected human on this land. For simplicity,assume that
Answer Preview: According to Table 207 the SNF from one year of operation of a LWR initially contains 10 kg of 241 A…

, Chapter: 10 -Problem: 6 >> Since it is not used up in a Carnot cycle, the gas used as a working fluid could be chosen to optimize the properties of the engine. What advantages would helium (a monatomic gas) have over air in a Carnot engine?
Answer Preview: A Carnot engine is independent of the nature of working substance Carnots theorem say…

, Chapter: 28 -Problem: 3 >> Evaluate the Coriolis factor f = 2?? sin ? at ±45? latitude. How large a pressure gradient (in millibars/km) is necessary to sustain a geostrophic wind at 30 m/s at this latitude?
Answer Preview: If v 30 m s …

, Chapter: 19 -Problem: 14 >> A dt plasma fusion reactor is operating in steady state at a temperature kBT = 15 keV and a pressure of 7 atm, where ??fv?  = 3 × 10?22 m3/s. What is the energy confinement time ?E required to satisfy the triple product criterion? What is the density of the plasma (particles per cubic meter), and how does this compare with the density of air at room temperature and pressure?
Answer Preview: At this temperature bremsstrahlung can be ignored so the second term in the denominator in …

, Chapter: 18 -Problem: 1 >> When exposed to a flux of thermal neutrons, most common materials absorb one or more neutrons and many become radioactive (?- -emitters). Explain how this is compatible with energy conservation. Can you name a naturally occuring nucleus that cannot absorb a neutron?
Answer Preview: Function approximation is a technique for estimati…

, Chapter: 28 -Problem: 12 >> Consider building a wind turbine at a wind power class 5 site. Assume that the hub height is 50 m and the blade length is 15 m, and that the turbine operates at 50% of the maximum theoretical efficiency. Estimate the average power output of the turbine.
Answer Preview: According to Table 28 2 class 5 at 50 m corresponds to powe…

, Chapter: 36 -Problem: 8 >> Systems that are colder than their environment have positive energy. Suppose a quantity of monatomic gas originally at ambient temperature and pressure (T0, p0) is adiabatically and reversibly expanded until its temperature has dropped to T. Compute its energy from eq. (36.25) and show that it is positive. How can this gas do useful work?
Answer Preview: The energy of the monatomic gas can be computed using the equation …

, Chapter: 19 -Problem: 8 >> The analysis of prompt and delayed neutrons in ?19.1.6 leads to the following formula for the time dependence of the neutron density, Analyze the time dependence of n(t) when ? d. For example, take tp = 2 ? 10?4 s, td = 12.5 s, and d = 0.0064, and compute n(t)/n(0) for ? = d/2 and ? = 2d. Transcribed Image Text:
Answer Preview: As shown in the figure the ratio ntn0 …

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, Chapter: 28 -Problem: 4 >> Suppose a gradient wind (see Box 28.1) is flowing along a circular isobar with radius R at a latitude of 45?. Compare the strength of the Coriolis and centrifugal forces on this flow as a function of wind speed. At what speed (as a function of R) are the two inertial forces equal?
Answer Preview: The magnitude of the centrifugal force per unit volume on a …

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, Chapter: 18 -Problem: 13 >> Estimate the height of the Coulomb barrier between two protons as follows: the strong nuclear interaction potential between two protons at large separation is given by eq. (14.5) Add to this the repulsive Coulomb potential given in eq. (18.8) Show that there sulting potential has a maximum at ? 5.5 fm, where its value is VC ? 0.2 MeV.
Answer Preview: The sum of the Coulomb plus strong nuclear interaction potentia…

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, Chapter: 25 -Problem: 16 >> Assuming a silicon P V array attains 20% efficiency over a lifetime of 25 years of use, where it is exposed to an average of 250 W/ m2, what is the total energy output of 1 m2 of PV cells (in joules). What quantity of coal would it replace (at 33% net efficiency)?
Answer Preview: At 20 efficiency 1 m 2 of solar cells exposed …

, Chapter: 25 -Problem: 4 >> Perovskites are a promising new class of materials for thin-film PV. Perovskites include a wide range of compounds, such as CH3NH3PbI3 , characterized by a crystal structure first observed in the mineral perovskite (CaTiO3). Perovskite solar cells have reached ~20% efficiency under laboratory conditions. They are relatively easy to manufacture and are composed of Earth-abundant elements. Investiga
Answer Preview: Advantages: 1. Low cost: Perovskite solar cells are relatively inexpensive to manufacture and requir…

, Chapter: 20 -Problem: 14 >> Rubidium-87, 87 Rb is a relatively common, very long-lived nuclide. Look up and compare its abundance and lifetime to 40K. How does 87 Rb decay? Why do you think it was omitted from the list of important naturally occurring radio nuclei?
Answer Preview: Both nuclei decay primarily by decay There are three issues i the relative activity in Earths crust …

, Chapter: 17 -Problem: 6 >> Radium-226 is a decay product of 238U . 226Ra has a half-life of 1600 years and is found in uranium ores. When it was first discovered and before radioactive decay was well understood, some mineral prospectors claimed to have discovered a rich deposit of radium (a few percent by mass) in a cave in the American midwest. What do you think of this claim?
Answer Preview: Ra 226 is a naturally occurring radioactive chemical In 1898 Pierre and Marie Curie discovered radium while researching with uranium ore The radioacti…

, Chapter: 23 -Problem: 3 >> Consider a location for a solar energy installation in Arizona, at latitude 34?. Compute the declination ?on the following dates: (i) March 20 (spring equinox),(ii) April 20. Compute the length of the day (from sun rise to sunset) at this location in Arizona on April 20.Assuming a clear day, compute the insolation on a horizontal surface at 6 a.m., noon, and 3 p.m., and compute the total insolatio
Answer Preview: The declination is defined to be the latitude at which the sun is directly overhead It is given by s…

, Chapter: 38 -Problem: 9 >> Show that the stator magnetic field of a three-phase generator has a constant magnitude and rotates with constant angular frequency. You can assume that the magnetic fields produced by the stator windings A, B,and C, are BA = e?A sin?t, BB = e?B sin(?t ? 2?/3), and BC = e?C sin(?t ? 4?/3), where e?A,B,C are unit vectors rotated by 120? with respect to one another. if you are comfortable with manip
Answer Preview: Let's being with the basic …

, Chapter: 17 -Problem: 3 >> There is no stable nucleus with A = 5. This has profound consequences for the way stars burn and form elements. The two candidates for stable nuclei with A = 5 are 52He and 53Li. Look up or figure out what they decay into and show that their decays are allowed by energy conservation.
Answer Preview: 4 He is anomalously stable so it is likely that …

, Chapter: 12 -Problem: 2 >> An insulated cylinder closed by a piston is initially filled with one liter of ice at –20 °C. The piston is pulled out, doubling the volume and initially creating a vacuum above the ice. Describe qualitatively what happens as the system comes into equilibrium at –20 °C. Now the system is slowly heated to 110 °C. Again describe in words, what is the state of the water in the cylinder?
Answer Preview: At 20C the ice will begin to melt and the liquid water will spread throughout th…

, Chapter: 26 -Problem: 3 >> A feedlot cow is fed 12 kg of corn daily for 255 days, and grows from 200 kg to 500 kg in that time. Estimating the energy densities of corn and cow both at roughly 15 MJ/kg (a very rough estimate, actually more of an overestimate for the cow), compute the ratio of corn energy input to cow energy output.
Answer Preview: The cow consumes 255 12 3060 kg …

, Chapter: 25 -Problem: 13 >> Given a silicon photovoltaic solar cell with open-circuit voltage Voc = 0.7V that operates at an overall 20% efficiency under 1000 W/m2 of normal illumination, (a) compute the current density from the collecting surface. (b) How many cells must be connected in series to make a 12 V voltage? (c) What surface area is needed to produce one ampere of current across 12 V?
Answer Preview: Voc = 0 7 v = 20% Incident power density = Pd = 1000 w…

, Chapter: 17 -Problem: 13 >> Explain how to read from Figure 17.8? the Q-value for?-decay predicted by the SEMF.? Transcribed Image Text: 10 dbmax bmax (A) + A dA 4He 3H 'H or n 50 100 150 200 250 A MeV
Answer Preview: For alpha decay where we have made the approximations described in the text a The fin…

, Chapter: 9 -Problem: 3 >> The Iron Age began around 1200 BCE, more than 2000 years after the first appearance of bronze in human history. It may come as a surprise, therefore, that the reaction Fe2O3 +3CO ? 2Fe +3CO2 is exothermic (?Hr = -25 kJ/mol) and has negative reaction free energy (?Gr = -29 kJ/mol) at NTP. So hematite can be quite easily reduced to iron by the CO produced in a hot, oxygen starved fire. Why, then, wa
Answer Preview: The answer to this question likely lies in the fact that the tempera…

, Chapter: 31 -Problem: 19 >> When a tidal barrage follows the water release profile shown in Figure 31.27 it only captures a fraction of the energy (31.35) available in the water stored at high tide. The discharge is indicated continuing until the outside and inside water levels are equal. Show that this fraction is given by. where ? = 2?/T and T ? 12 h. For the parameters shown in the figure, where ?t1 = ?/4 and ?t2 = 5
Answer Preview: At time t a mass of water dm gAdz is released with a hydraulic head of z t h t …

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, Chapter: 22 -Problem: 5 >> Compute the frequency ?max corresponding to the maximum power of radiation for a blackbody at temperature T = 280 K. This is roughly the average temperature of Earth’s surface. Compute the wavelength corresponding to this frequency.
Answer Preview: Evaluating eq 2214 for T 280 K Then A …

, Chapter: 13 -Problem: 2 >> Discuss the distinction between an adiabatic and an isentropic process. For example, how can it be that a compressor that works very quickly, allowing negligible heat transfer, can nevertheless increase the entropy of a gas?
Answer Preview: we know S Sgen dQ T an isentropic process is a reversible adiabatic …

, Chapter: 29 -Problem: 12 >> In §29.4.1 it is asserted that eq. (29.28) describes the steady, circulation-free flow of an incompressible ideal fluid around a cylinder. To confirm this, verify (a) that va ? v? x? as r ? ?; (b) that no fluid flows into or out of the cylinder; (c) that the circulation is zero around any circle of radius r > R; (d) that ? × va = 0 (zero vorticity) and ? · v? = 0 (incompressibility) everywhere out
Answer Preview: a Since the second term in the first form of eq 29 28 Falls like 1 r 2 this result is obvious b Th…

, Chapter: 25 -Problem: 3 >> Suppose a PV with gap Egap were illuminated by a laser that produces monochromatic light with frequency v0. How would the collection efficiency of the PV vary with?
Answer Preview: The efficiency of a PV is determined as the fractio…

, Chapter: 19 -Problem: 2 >> Show from eq. (19.9) that in an infinite, homogeneous graphite-moderated reactor, the resonance escape probability is given by p(y) = exp(?17.28 (1/(9.3 + 4.9y))0.514), where y is the ratio of moderator to fuel. Transcribed Image Text: 0.514 2.73 n(238 U) Es p = exp ($)
Answer Preview: Dividing through by number density of 238 U in the argument of the ex…

, Chapter: 17 -Problem: 1 >> How can the neutron be unstable in free space, but stable when inside a nucleus?
Answer Preview: If neutron decays in side the nucleus then it will decays t…

, Chapter: 24 -Problem: 7 >> Consider the examples of single- and double-pane glass-covered collectors described in §24.2.1. Verify the quoted results for the efficiency as a function of Tb, Tg, and I0. In the case of double glazing, compute the temperature of the intermediate glass plate. Plot the efficiency as a function of Tb for 25 ?C < Tb < 100 ?C when Tg = 280K and I0 = 1000 W/m2.
Answer Preview: Double gl azing has two glass surfaces and two air spaces between the glass surfaces The air spaces …

, Chapter: 38 -Problem: 5 >> Figure 30.2 shows the power coefficient for a wind turbine blade as a function of tip-speed ratio. In light of this, explain why a wind turbine constrained to operate at fixed rotor speed is less efficient than one with variable speed. Transcribed Image Text: (a) (b)
Answer Preview: A fixed-speed wind turbine always will spin at the same generator…

, Chapter: 19 -Problem: 4 >> Show that an infinite, homogeneous reactor fueled with natural uranium (0.72% 235U) and moderated by heavy water (D2O) can sustain a fission chain reaction. What is the optimal ratio of moderator to fuel?
Answer Preview: The relevant expressions for p and f are Numerical eva…

, Chapter: 4 -Problem: 1 >> Explain why the strings that play lower frequency notes on a guitar or violin are generally thicker and less tightly strung than the strings playing higher notes.
Answer Preview: Violin Guitar are musical instruments which produce sound from the vibration of s…

, Chapter: 32 -Problem: 2 >> Make a very rough estimate of the thermal energy content of Earth, assuming that the core has radius 3480 km, temperature 4000 K, density 11000 kg/m3 and heat capacity 800 J/K kg, and that the rest of the planet, dominated by the mantle, has radius 6370 km, temperature 2000 K, density 4500 kg/m3 and heat capacity 1200 J/K kg. Numbers for a more detailed model of the planetary interior can be found
Answer Preview: The thermal energy content of a sphere of density 11000 kg m 3 …

, Chapter: 31 -Problem: 2 >> In contrast to traditional hydropower plants where water is stored behind large dams, run of the river (ROR) hydro-plants use flowing water with little or no water storage (pondage). Investigate and discuss the relative advantages and disadvantages of ROR versus traditional hydropower. Include environmental, social, as well as technical issues.
Answer Preview: ROR system has great advantages over conventional hydropower systems. This is …

, Chapter: 20 -Problem: 3 >> Show that a particle’s range (see §20.2.1) expressed as a function of its initial velocity is proportional to its mass and inversely proportional to the square of its charge and to the electron density of the material.
Answer Preview: The right hand side of Bethes formula for the st…

, Chapter: 6 -Problem: 4 >> A water bed replaces an ordinary mattress with a plastic bag filled with water. If the ambient temperature is below body temperature, water beds must either be heated or covered with a relatively thick layer of insulating foam. Why should this be necessary for a water bed, but not for an ordinary mattress?
Answer Preview: Water of the waterbed is a better conductor 0 6 Watts mete…

, Chapter: 31 -Problem: 16 >> Consider building a tidal barrage along a straight section of beach in California. Assume that the average tidal range is 3 m, with two high tides a day. Assume that the tidal basin is 20 m wide and extends for 1 km along the coast. Assume that all available energy from both incoming and outgoing tides is extracted. Compute the average power output of this installation. Do you think this installat
Answer Preview: The amount of energy that can be answeed from either filling …

, Chapter: 17 -Problem: 14 >> Show that the longest-lived isotope of radium, 22688Ra,is energetically allowed to decay by emission of a146C nucleus. This decay has been observed with aprobability of 3.2 × 10?9.
Answer Preview: Q 226 Ra 214 Pb …

, Chapter: 23 -Problem: 7 >> Compute the integrated daily insolation at several different latitudes on July 30 and compare with Figure 23.6. Transcribed Image Text: 10 1= 0° d= 20° A= 40% A = G0% A = 80 %3D Mar 22 June 22 Sept 22 Dec 22 Mar 22 (a) time of year 20 40 60 80 latitude average daily insolation (hours of perpendicul
Answer Preview: The angle of incoming solar radiation influences seasonal temperatures of locations at differen…

, Chapter: 32 -Problem: 6 >> Compute the draw down coefficient (32.11) in a simple model where the geothermal reservoir is a large cylindrical volume with height h much smaller than the radius r (see Figure 32.17) Assume that the pressure is constant at pw in a small cylinder of the radius of the wellbore rw, and that flow is radial and vertically uniform outside that volume. Show thatUse conservation of mass to show that |u|
Answer Preview: The mass flow rate through a cylinder of radius r m r is giv…

, Chapter: 20 -Problem: 7 >> To a first approximation for computing stopping power, living tissue can be approximated as water. Using data on the range of protons in water, estimate the energy of a proton required to place its Braggpeak on a tumor at a depth of 10 cm inside a body.
Answer Preview: This problem requires information available online Data …

, Chapter: 13 -Problem: 7 >> The efficiency of the idealized Carnot-like Rankine cycle of Figure 13.12(b)  is higher than for fixed but lower than the Carnot limit for  Transcribed Image Text: 3 T 800 700 z 600 P+ Tvap (p) 500 P- 400 300 4. 2 4 6. 8 (b) entropy [kJ/kg K] temperature [KI 00
Answer Preview: If one has the function value and n derivatives at one point x0 then one can calculate a …

, Chapter: 30 -Problem: 7 >> Axial-momentum analysis led to a power coefficient CP = 4a(1 ? a)2 for a HAWT eq. (30.7) Compute the power coefficient another way: start from the tangential force per unit length f T in the simple model that led to eq. (30.12) implement the axial momentum theory constraint (30.15) find the torque per unit length d?/dr R and compute the power Show that the result is the same as the result of the a
Answer Preview: Combining the expression for f T from eq 30 12 with the c…

, Chapter: 19 -Problem: 3 >> Consider an infinite, homogeneous reactor fueled with uranium enriched to 3% and moderated by graphite with a ratio of graphite : uranium of 800 : 1. Find k?. To find p, you can ignore the uranium when computing ??? ?and in the calculation of the scattering cross section. (You can assume ? = 1.) Table 19.1 ? Table 19.2
Answer Preview: From eq 198 Next compute the resona…

, Chapter: 7 -Problem: 1 >> We make a big deal about the linearity of quantum mechanics. Is classical mechanics linear? Consider, for example, two solutions to Newton’s laws for motion in Earth’s gravitational field, x1(t) and x2(t). Both obey mx?(t) = - GmM|x|. Show that a linear combination of x1 and x2 is not a solution. Can you think of a type of force for which solutions do obey superposition?
Answer Preview: Classical mechanics is generally considered to be linear in th…

, Chapter: 31 -Problem: 14 >> Show that energy loss from Earth’s rotational kinetic energy at a rate of 3.9 TW (including dissipation and energy transferred to lunar orbit) corresponds to an increase in length of day of 2.3 ms/century. You may take Earth’s moment of inertia about its rotational axis to be I = 8.0 × 1037 kgm2.
Answer Preview: For rotational motion of Earth E kin …

, Chapter: 17 -Problem: 8 >> Pressure can be defined as the rate of change of energy with volume, p = ?E/?V. Similarly, the surface analogue of pressure, surface tension, is defined as the rate of change of energy with surface area a, ? ? ?E/?a at constant volume. Ignoring the effects of symmetry,Coulomb, and pairing energies, compute the surface tension of a nucleus as described by the empirical parameters of the SEMF. The s
Answer Preview: Ignoring symmetry Coulomb and pairing energies BA v …

, Chapter: 13 -Problem: 1 >> Why is water not a suitable fluid for a vapor-compression kitchen refrigerator? What about for an air conditioner intended to operate between 24 °C and 40 °C?
Answer Preview: water will not act as a good refrigerant in VC cycle because due to its high boiling point 100C ma…

, Chapter: 30 -Problem: 9 >> Model the blades of a HAWT rotor as rods of equal length and mass, equally spaced around a circle, rotating with angular frequency ?. Compute the moment of inertia of the rotor about the vertical axis. Show that the moment of inertia is independent of time as long as there are three or more blades.
Answer Preview: The moment of inertia of a rod inclined at an angle …

, Chapter: 19 -Problem: 9 >> When a reactor is turned off, the amount of 135Xe decreases as it decays, but grows as 135I decays to it. Write a pair of differential equations that describe the time rate of change of the numbers NI and NX of 135I and 135Xe nuclei respectively, and solve these equations assuming that NI = N0I and NX = N0X at t = 0. Show (using the measured half-lives of 135I and 135Xe) that the resulting curve o
Answer Preview: The differential equations are N I N I I and N X N I …

, Chapter: 6 -Problem: 1 >> People usually discuss their experience of heat and cold in terms of temperature. Closer consideration, however, suggests that it is heat conduction rather than temperature that matters. What do you think? Have you ever taken a sauna? Or touched a metal surface at –30?C?
Answer Preview: Some of the factors contributing to the feeling of heat are as follows Wind Speed Higher spee…

, Chapter: 24 -Problem: 10 >> Consider an idealized flat-plate solar collector with no conduction or convection losses, and with insolation 1000W/m2 incident at an angle of 45? from the vertical. Assume that the collector is horizontal and is covered with a pane of glass transparent to incoming radiation but opaque to outgoing (IR) radiation. The glass is kept at 300 K by the external environment. Compute the temperature of th
Answer Preview: Radiative balance at the absorber without the …

, Chapter: 18 -Problem: 17 >> The Coulomb barrier keeping two nuclei apart is given by V(r) = Z1Z2e2/(4??0r), where r is the relative separation of the two nuclei. Assume that V reaches its maximum value VC when r ? R1 + R2, where Rj is the radius of the

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