What happens to the work done when a jar of orang;,u mikp+jj: be juice is vigorously shaken?

When a hot object warms a cooler object, dzd6 zh-xjn 9u,,r2mgvoes temperature flow between them? Are the temperature changes of th6,-u2dv9 xmjhg zr z,ne two objects equal?

(a) If two objects of different temperatures are placed in contact, will)mrj0/.mp rz+cd. vc j heat naturally flow from the object with higher internal energy to the object with lower internal energy? ( p)/mc.rvzjcd .+0jrm b) Is it possible for heat to flow even if the internal energies of the two objects are the same? Explain.

In warm regions where tropical planb: :8dp1nay) pkg6zx nts grow but the temperature may drop below freezing a few times in the winter, the destruction of sensitive plants due to freezing can b nzg nyp:xk pad:)861be reduced by watering them in the evening. Explain.

The specific heat of water ov 4dpr/*v;seis quite large. Explain why this fact makes water particulad so *;vepvr4/rly good for heating systems (that is, hot-water radiators).

Why does water in a metal canteen sfq kp5 zs;+o6a 21hddstay cooler if the cloth jacket surrounding the cad625fa +1pkoq ;zdshsnteen is kept moist?

Explain why burns caused by steam on the skin are ofte1 acd7uqa/lgxny2tyo /d v,gio ( 7(m4n more severe than burns caused by water atg ynv/g idq1ot7,dl 7 2x(/caaum4 yo( 100 $^{\circ} C$ .

Explain why water cools (its temperatur1j ii*cw99-zmvkic:)r ouk1t e drops) when it evaporates, using the concepts of latent he m91o i* j1ivzcikwruk)9t-:cat and internal energy.

Will potatoes cook faster if the water is boiling fasteox um6n k1q*ofu2 k0l v;4b9nlr?

Does an ordinary electric fan cool uyl9;f / vlvz632desc the air? Why or why not? If not, why use it?

Very high in the Earth’s atmosphere, the temperat t yi dqxts675g5l5+xhure can be 700 $^{\circ} C$ . Yet an animal there would freeze to death rather than roast. Explain.

Explorers on failed Arctic expeditiono a nvib8t; :ki8(p5als have survived by covering themselves with snow. Wh( a tiakp;i5blno8:v8y would they do that?

Why is wet sand at the beach cooler to walk on than dry syg0s:f er :e9band?

If you hear that an object has “hibkl4r z n0 k kdgvn084mds97j-gh heat content,” does that mean that its temperature is hikdz0nns 0jgvk b m44978lrkd- gh? Explain.

When hot-air furnaces are used to heat a house, why is it important that therazk+n* k/no . bv5ml:fkhy4 )ne be a vent for air to retu:n/4fzv5*n+)akmkk o nbylh.rn to the furnace? What happens if this vent is blocked by a bookcase?

Ceiling fans are sometimes reversible, so that they drive the air down in omf/ 8re w: ewb2vn5m3gne season and pull it up in another season. Whic :n3 8ermm2v /fwewgb5h way should you set the fan for summer? For winter?

Down sleeping bags and parkas are often specified as so manyzs7 nl8t44gst inches or centimeters of loft, the actual thickness of thss g z4tn48l7te garment when it is fluffed up. Explain.

Microprocessor chips have a “heat sink” glued on top that looks like o-/ +f) f 9rk fk;m8xyy)pjamta series of fins. Why itp /a)okr ) fmy8kx jf;yf9-m+s it shaped like that?

Sea breezes are often encountered on sunn 0/olaokwj- t.ge lgfn (alcss o/kr.+/,(;pqy days at the shore of a large body of water. Explain in light of the fact that the temperatgaolofk. .(r+- lnw //a(ce;/ kl0osjgq ts,p ure of the land rises more rapidly than that of the nearby water.

The floor of a house on a foundation under which the air can flow is often pnnz g3mi 1;s5 1t2dlo:fl3ykcooler than a floor that rests directly on ti52;l3:g3z oy pnlknf1std m1 he ground (such as a concrete slab foundation). Explain.

A 22 $^{\circ} C$ day is warm, while a swimming pool at $22\; ^{\circ}C$ feels cool. Why?

Explain why air temperature readings are always taken with the thermometer wrn1):j,. (kfkw ezoiin the shadej nfkw) k:i,( zrwe.o1.

A premature baby in an incubator can be dangeroumwawm kvy 7)8vu82gw ;sly cooled even when the air temperature in the incubator isv 8)w mgkmy8ww2a;uv7 warm. Explain.

Why is the liner of a thermos bottle silvered (Fig. 14–15), and why doesrpuajyw*08-cx qu) y- it have a vacuum between iawj-cu * r0pqx8)yy -uts two walls?

Imagine you have a wall that is very well insulated — it has a very high thu ncy +w7ph2f/ u()bfqermal)ywh7 c+(qbu fun/p2f resistance, $R_1$ Now you place a window in the wall that has a relatively low R-value, $R_2$ What has happened to the overall R-value of the wall plus window, compared to $R_1$ and $R_2$ [Hint: The temperature difference across the wall is still the same everywhere.]

Heat loss occurs through windows by the following processes: (1) ventilation arore56) 2jxsk0s2brjy6 e. udc/ hku; lhund edges; (2) through the frame, particularly if it is metal; (3) through the glass panes; and (4) radiation. (a) For the first three, what is (are) the mechanism(s): conduction, convection, or radiation? (b) Heavy curtains reduce which of these heat losses? Explain 2kjurdb.hsx) 6e5y r62ekhls0 ;uj/cin detail.

A piece of wood lying in the Sun+wfi)5ay*5jc3w f m ka absorbs more heat than a piece of shiny metal. Yet the wood feels le3 c)mkfj* a5w+ai5 fwyss hot than the metal when you pick it up. Explain.

The Earth cools off at night much more quickly when the weathe iq-3df9je s1sr is clear than when cl1ef-q ss 39dijoudy. Why?

An “emergency blanke4hj16ttwae n*t” is a thin shiny (metal coated) plastic foil. Explain how it can h6ja4n *1 tewthelp to keep an immobile person warm.

Explain why cities situated by the ocb owibs7s ,;jeyw-9 18c ej1vlean tend to have less extreme temperatures than inland cities at the s -ce;e,yi9ow7jbjs1 v8lwb1same latitude.

  How much heat (in joules) is required to rikc;c1rb3g n 7aise the temperature of 30.0 kg of water from3r1i n7 bckg;c 15 $^{\circ} C$ to 95 $^{\circ} C$ ?    $ \times10^{7 }\,J$

  To what temperature will 7700 J of heat raise 3.;kzykyki5* corwt *-3 0 kg of water that is initially at 105;kk3 ytz*i*cyr wk-o.0 $^{\circ} C$ ?    $^{\circ} C$

  An average active person consum;v bdlwwg1 9.ees about 2500 Cal a day.
(a) What is this in joules?   $ \times10^{7 }\,J$
(b) What is this in kilowatt-hours?    kWh
(c) Your power company charges about a dime per kilowatt-hour. How much would your energy cost per day if you bought it from the power company? Could you feed yourself on this much money per day?    dollars per day

A British thermal unit (Btu) is a unit of heat in 7xf r59ov59chig7hvfthe British system of units. One Btu is defined as the heat needihofr9h vg5 7f95 7cxved to raise 1 lb of water by 1 F $^{\circ} $ . Show that
1Btu = 0.252kcal=1055J

  A water heater can gexsu 4s*oar0 (tnerate $32,000\,kJ/h$ How much water can it heat from 15 $^{\circ} C$ to 50 $^{\circ} C$ per hour?    kg/h

  A small immersion heater is rated at p9b)gq:dir.j 350 W. Estimate how long it will take to heat a cup 9bg)riq. j :pdof soup (assume this is 250 mL of water) from 20$^{\circ} C$ to 60$^{\circ} C$ .    min

  How many kilocalories are generated when the brakes are used to jze vjt1 1o8;hu5vye)bring a 1200-kg car to restv8hj1ue1o)t e 5 jy;zv from a speed of $95\,km/h$ ?    kcal

  An automobile cooling system holds 16 L of water. How much heat does it absorb hz,e9hua a:20/d-uc kacj7 psif its temperature rises from /0ap 2 -ce uas7,khz9ah :cjud20$^{\circ}C $ to 90$^{\circ} C$?    $ \times10^{ 6}\,J$

  What is the specific heat of a metal substance if 135 kJ of heat is neede*4xa msb)akxz ;n /q4ld to raise 5.1 kg of the metal fr b;mk4 nazx*a4xq)l/som 18.0$^{\circ}C $ to 31.5$^{\circ} C$ ?    $J/kg\cdot\,C^{\circ} $

  Samples of copper, aluminum, avyix4 :te ed3g9/,:btl x1wgtnd water experience the same temperature rise when they absorb the same amount of heat. What is the ratio of their masses? [Hint: See Tab gwv ted :94yti31gx:/lex ,tble 14–1.]$m_{Cu}$ : $m_{Al}$ : $m_{H_2O}$ =    :    :   

  A 35-g glass thermometer reads 21.6b virxi 0:i.4u$^{\circ} C$ before it is placed in 135 mL of water. When the water and thermometer come to equilibrium, the thermometer reads 39.2$^{\circ} C$ . What was the original temperature of the water?$T_{iH_2O}$ =    $^{\circ}C $

  What will be the equilibrium temperature when a 245-g block ofuib*wq*dvptk ( 59y5 v copper at 285$^{\circ}C $ is placed in a 145-g aluminum calorimeter cup containing 825 g of water at 12.0$^{\circ} C$ ? $T_{eq}$ =    $^{\circ} C$

  A hot iron horseshoe (mass = h4mj,c8j9ec e $0.4\,kg$) just forged (Fig. 14–16), is dropped into 1.35 L of water in a 0.30-kg iron pot initially at 20.0$^{\circ} C$ . If the final equilibrium temperature is 25.0$^{\circ} C$, estimate the initial temperature of the hot horseshoe.    $^{\circ} C$

  A 215-g sample of a substance is heated to eh0lks6q/jtl6v mg:, 330$^{\circ} C$ and then plunged into a 105-g aluminum calorimeter cup containing 165 g of water and a 17-g glass thermometer at 12.5$^{\circ} C$ . The final temperature is 35.0$^{\circ} C$ . What is the specific heat of the substance? (Assume no water boils away.)    $J/kg \cdot C^{\circ} $

  How long does it take a 750-W coffeepot to bring to a (ytfk:/dbf jlqv /)0.fgns r)boil 0.75 L of water initially a f( /y0.: nkf/)rftjvb)qsdgl t 8.0$^{\circ}C$? Assume that the part of the pot which is heated with the water is made of 360 g of aluminum, and that no water boils away. $\approx$    min (Round to the nearest integer)

  Estimate the Calorie content of 75 g of candy from the follow eqb m4-. dgp+,cyd3tsing measurements. A 15-g sample of the candy is allowed to dry before putting b ts-,d4cgqym3 . ped+it in a bomb calorimeter. The aluminum bomb has a mass of 0.725 kg and is placed in 2.00 kg of water contained in an aluminum calorimeter cup of mass 0.624 kg. The initial temperature of the mixture is 15.0$^{\circ}C $ , and its temperature after ignition is 53.5$^{\circ} C$ .    Cal

  When a 290-g piece of iron t6:0)bi9xgd 8o 2p3uwotwy qy at 180$^{\circ} C$ is placed in a 95-g aluminum calorimeter cup containing 250 g of glycerin at 10$^{\circ} C$ , the final temperature is observed to be 38$^{\circ}C $ . Estimate the specific heat of glycerin.    $J/kg \cdot C^{\circ} $

  The 1.20-kg head of a hammerk,1ok*kyfeu, has a speed of $6.5\,m/s$ just before it strikes a nail (Fig. 14–17) and is brought to rest. Estimate the temperature rise of a 14-g iron nail generated by 10 such hammer blows done in quick succession. Assume the nail absorbs all the energy.    $C^{\circ} $

  The heat capacity, C, of an object is defined as the amount of heatxc-e.gar5 z3 iwdk4j: needed to raise its tempera-3ji.w x:4a dr cg5ezkture by 1 $C^{\circ} $ . Thus, to raise the temperature by $\Delta\,T$ requires heat Q given by
$Q\,=\,C\,\Delta T$
(a) Write the heat capacity C in terms of the specific heat, c, of the material.
(b) What is the heat capacity of 1.0 kg of water?    $ \times10^{3 }\,J/C^{\circ}$
(c) Of 25 kg of water?   $ \times10^{ 5}\,J/C^{\circ}$

  How much heat is needed tovf+yv+m4i qg z6n0.me3ji 7v s melt 16.50 kg of silver that is initially at 20$^{\circ} C$?    $ \times10^{6 }\,J$

  A 0.095-kg aluminium sphere is dropped frow vlv+u q2c (hdm5,)/rf)es-q9threnm the roof of a 45-m-high building. If 65% of the thermal energy produced w)(5wvv ,teqn q2-c/ )u9l+rfhsdmr h ehen it hits the ground is absorbed by the sphere, what is its temperature increase?    $C^{\circ}$

  During exercise, a person may give off 180 kcal of heat in 30 min by 69mlt zld aq2hsq*i0e 1vi8)pevaporation of water from the skin. How much le tv0)pqiq ds2*maz i9861hlwater has been lost?    kg

  If $2.80 \times10^{ 5}J$ of energy is supplied to a flask of liquid oxygen at -183$^{\circ} C$ how much oxygen can evaporate?    kg

  A 30-g ice cube at its melting point is dropped into an inss4ir8l7n, kgygshyk0 c0r9 a1ulated container of liquid nitrogen. 0i4 l0gasrg 1nsk9hr87y ck,y How much nitrogen evaporates if it is at its boiling point of 77 K and has a latent heat of vaporization of $200\,kJ/kg$ Assume for simplicity that the specific heat of ice is a constant and is equal to its value near its melting point.    kg

  A cube of ice is taken from the freezer at -8.5d/jccs: hi95u $^{\circ} C$ and placed in a 95-g aluminum calorimeter filled with 310 g of water at room temperature of 20.0$^{\circ} C$. The final situation is observed to be all water at 17.0$^{\circ} C$. What was the mass of the ice cube?    $ \times10^{-3 }$ kg

  An iron boiler of mass 230 kg contains 830 kg of watir 41ri gx6m3u.j ;cjfer at 18$^{\circ} C$. A heater supplies energy at the rate of $52,000\,kJ/h$ How long does it take for the water
(a) to reach the boiling point,$\approx$    h (Round to one decimal place)
(b) to all have changed to steam?$\approx$    h (Round to the nearest integer)

  In a hot day’s race, a bicyclis- c86rcj:nfyt(xnpv 1 t consumes 8.0 L of water over the span of four hours. Making the approximation that allyv-jr( 6tn :ccp8nf1x of the cyclist’s energy goes into evaporating this water as sweat, how much energy in kcal did the rider use during the ride? (Since the efficiency of the rider is only about 20%, most of the energy consumed does go to heat, so our approximation is not far off.)    kcal

  What mass of steam at s dkcj94j,1 d mle*ln5fv33rs100$^{\circ} C$ must be added to 1.00 kg of ice at 0$^{\circ} C$ to yield liquid water at 20$^{\circ} C$ ?    kg

  The specific heat of meqm)bdy,.os 3ynh.k z -rcury is $138\,J/kg$$\cdot\,C$ Determine the latent heat of fusion of mercury using the following calorimeter data: 1.00 kg of solid Hg at its melting point of -3.9$^{\circ} C$ is placed in a 0.620-kg aluminum calorimeter with 0.400 kg of water at 12.80$^{\circ} C$ ; the resulting equilibrium temperature is 5.06$^{\circ} C$ .    $ \times10^{ 4}$ J/kg

  A 70-g bullet traveling at sw6 nlbeb .)iv,v6 3es$250\,m/s$ penetrates a block of ice at 0$^{\circ} C$ and comes to rest within the ice. Assuming that the temperature of the bullet doesn’t change appreciably, how much ice is melted as a result of the collision?   g

  A 54.0-kg ice-skater usjmpp o0hrh+a mb sm33 nm018z) p 23wrlc49bmoving at $6.4\,m/s$ glides to a stop. Assuming the ice is at 0$^{\circ} C$ and that 50% of the heat generated by friction is absorbed by the ice, how much ice melts?    g

  At a crime scene, the forensic investigator notes thatvr jfn(*magrv-h g(:)v1k b0b the 8.2-g lead bullet that was stopped in a doorframe apparently melted completely g vb0-jg(v(:k)m*brnr 1va fhon impact. Assuming the bullet was fired at room temperature (20$^{\circ} C$ ), what does the investigator calculate as the minimum muzzle velocity of the gun?    m/s

  One end of a 33-cm-long aluminum rod with a diameter od (rihel24lz) f 2.0 cm is kept at 460$^{\circ} C$ , and the other is immersed in water at 22$^{\circ} C$ . Calculate the heat conduction rate along the rod.    W

  Calculate the rate of heat flow by conductu3n oxt(fttp z*j: 0y a;zx/9rion in Example 14–10, assuming that there are strong gusty winds and tn pr 9xzjfux:*3tzat/0 o( y;the external temperature is -5$^{\circ} C$   $ \times10^{4 }$ W

  (a) How much power is radiated by aswyx r5 ff+ /*fcyogb:-zu*4v tungsten sphere (emissivity $e\,=\,0.35$) of radius 22 cm at a temperature of 25$^{\circ} C$ ?    W
(b) If the sphere is enclosed in a room whose walls are kept at -5$^{\circ} C$ what is the net flow rate of energy out of the sphere?    W

  Heat conduction to skin. Suppose 204r t3, ;:tt9gp;ujbnyv m3g h sb3xr.h0 W of heat flows by conduction from the blood capilla; t:j3nrr h t3mgb bx;tuy3,9sp.gh4 vries beneath the skin to the body’s surface area of $1.5\,m^2$ If the temperature difference is 0.50 $C^{\circ} $ , estimate the average distance of capillaries below the skin surface.    $ \times10^{-4 }$ m

  Two rooms, each a cube 4.0 m per sidktv:xb )exa:q;))rgl e, share a 12-cm-thick brick wall. Because ofgxx q atkr:: e;vlb))) a number of 100-W lightbulbs in one room, the air is at 30$^{\circ} C$, while in the other room it is at 10$^{\circ}C $. How many of the 100-W bulbs are needed to maintain the temperature difference across the wall?    bulbs

  How long does it take the .ls;+r3s0 nlqcxzjo 5Sun to melt a block of ice at 0$^{\circ} C$ with a flat horizontal area $1.0\,m^2$ and thickness 1.0 cm? Assume that the Sun’s rays make an angle of 30$^{\circ} $ with the vertical and that the emissivity of ice is 0.050.    h

  A copper rod and an aluubo0acg,t s c1 ;7.4gwx8dq ns( /xszxminum rod of the same length and cross-sectional area are attached end to end (Fig. 14–18). The copper end is placed in a furnace maintai40os1(a dsb8c .gu,gx tn/xq7 cz ;xwsned at a constant temperature of 250$^{\circ} C$. The aluminum end is placed in an ice bath held at constant temperature of 0.0$^{\circ} C$ . Calculate the temperature at the point where the two rods are joined.    $^{\circ} C$

  (a) Using the solar constant, estimate the rate afe5z: jdxl tc+35 +yidt which the whole Earth receives energy from j+ d5zdc5+ 3eyl:fit xthe Sun.    $ \times10^{17 }$W
(b) Assume the Earth radiates an equal amount back into space (that is, the Earth is in equilibrium). Then, assuming the Earth is a perfect emitter ($e\,=\,1.0$) estimate its average surface temperature.    $^{\circ} C$

  A 100-W lightbulb generates 95 W l ,mn,tgj +5bz4 0c8(gmvlfueof heat, which is dissipated through a glass bulb that has a radius of 3.0 cm and is 1.0 mm thick. What is the difference in temperature between the inner and outer surfaces of the glajmvm 0 ,c(l f8t bgen+5zlug4,ss?   $^{\circ}C $

  Suppose the insulating qualities of the wall of a house come mainlsk :y0f,au:9pand 0 h.,ri: .w keuwmjy from a 4.0-in. layer of brick and an R-19 layer of insulation, as shown in Fig. 14–19. What is the tekaim.rj:ufh:,9 s0 a,ndp: kw w0u.yotal rate of heat loss through such a wall, if its total area is $240ft^2$ and the temperature difference across it is 12 $F^{\circ} $?    Btu/h

A double-glazed window ha17/s tvct4ueldc; o j9s two panes of glass separated by an air space, Fig. 14–20. (a) Show 7v /4c9cl t1dst;ju eothat the rate of heat flow through such a window by conduction is given by
$\frac{Q}{t}$ = $\frac{A(T_2-T_1)}{l_2/k_1+l_2/k_2+l_3/k_3}$,
where $k_1$,$k_2$ and $k_3$ are the thermal conductivities for glass, air, and glass, respectively. (b) Generalize this expression for any number of materials placed next to one another.

  Approximately how long should it take 11.a4 tgw:8;ks v; j2brst0 kg of ice at 0$^{\circ}C $ to melt when it is placed in a carefully sealed Styrofoam ice chest of dimensions $25\,cm\times\,35\,cm\times\,55\,cm$ whose walls are 1.5 cm thick? Assume that the conductivity of Styrofoam is double that of air and that the outside temperature is 32$^{\circ} C$.    $ \times10^{4 }$s

  A soft-drink can contains about 0.20 kp :.1vsqokb/ /xlqi .pg of liquid at 5$^{\circ}C $. Drinking this liquid can actually consume some of the fat in the body, since energy is needed to warm the water to body temperature (37$^{\circ} C$). How many food Calories should the drink have so that it is in perfect balance with the heat needed to warm the liquid?    C

  If coal gives off $30\,MJ/kg$ when it is burned, how much coal would be needed to heat a house that requires $ 2.0\times10^{5 }\,MJ$ for the whole winter? Assume that 30% of the heat is lost up the chimney.    kg

  To get an idea of how much thermal energy is7tnb 5dh hz ;zy/h9;uh contained in the world’s oceans, estimate the heat liberated when a cube of ocean water, 1 km on each side, is coole hyhnh7z bd;;95/ut zhd by 1 K. (Approximate the ocean water as pure water for this estimate.)    $ \times10^{ 15}\,J$

  A 15-g lead bullet is tes-hz+ 2vzx c3boted by firing it into a fixed block of wood with a mass of 1.05 kg. The block and imbedded bullet together absorb all+oczx b32v h-z the heat generated. After thermal equilibrium has been reached, the system has a temperature rise measured as 0.020 $C^{\circ} $. Estimate the entering speed of the bullet.    m/s

  (a) Find the total power radiated into space by the Sun, assuming itibo uuohk); +* to be a perfect emitteri* +o)uob;huk at $T\,=\,5500K$ The Sun’s radius is $7.0 \times10^{ 8}\,m$    $ \times10^{ 26}\,W$
(b) From this, determine the power per unit area arriving at the Earth, $1.5 \times10^{ 11}\,m$ away (Fig. 14–21).    $ \times10^{ 3}\,W/m^2$

  During light activity, a 70-kg pem ulw +dde7-o7nl-u e2rson may generate $200kcal/h$ Assuming that 20% of this goes into useful work and the other 80% is converted to heat, calculate the temperature rise of the body after 1.00 h if none of this heat were transferred to the environment.    $C^{\circ} $

  A 340-kg marble boulder rolls off the top of a cliff and falls a vertical dr(m0: 2haw1gk+nte q height of 140 m before striking the ground. Estimate the temperature rise of the rock0ew(q a +1nm:hgdtr2k if 50% of the heat generated remains in the rock.    $C^{\circ} $

  A 2.3-kg lead ball is dropped into a 2.5-L insulav -mh1j+*4mt .2ohmxhyq)ak vted pail of water initially at 20v1qth4m + myxh. -a)m2v jo*kh.0$^{\circ} C$. If the final temperature of the water–lead combination is 28.0$^{\circ} C$, what was the initial temperature of the lead ball?    $^{\circ}C $

  A mountain climber wears a goose down jacket 3.5 cm thick 3nf6z ol0e3plhv5+utwith total surface aren3+ uvl5hl30 eptzf6oa $1.2\,m^2$ The temperature at the surface of the clothing is -20$^{\circ}C $ and at the skin is 34$^{\circ} C$. Determine the rate of heat flow by conduction through the jacket
(a) assuming it is dry and the thermal conductivity k is that of down,    W
(b) assuming the jacket is wet, so k is that of water and the jacket has matted to 0.50 cm thickness.    W

  A marathon runner has an average metab *z)jtwls* sl.olism rate of about $950\,kcal/h$ during a race. If the runner has a mass of 55 kg, estimate how much water she would lose to evaporation from the skin for a race that lasts 2.5 h.    kg

  Estimate the rate at which heat can be conducted from tn8r9/ 5qyjdz 2py3mq(l ur6mdhe interior of the body to the surface. Assume that the 5 3dqjl2rz 8y um9yd(6 nqp/mrthickness of tissue is 4.0 cm, that the skin is at 34$^{\circ}C $ and the interior at 37$^{\circ}C $, and that the surface area is $1.5\,m^2$ Compare this to the measured value of about 230 W that must be dissipated by a person working lightly. This clearly shows the necessity of convective cooling by the blood.    W

  A house has well-insulated walls 17.5 cm thick (assume conductivity of air) anwodj 0xivas x0w1g60j2- y1b ud a1s61ioa w0djb0gx x wvu0jy-2rea $410\,m^2$ a roof of wood 6.5 cm thick and area $280\,m^2$ and uncovered windows 0.65 cm thick and total area $33\,m^2$
(a) Assuming that heat is lost only by conduction, calculate the rate at which heat must be supplied to this house to maintain its inside temperature at 23$^{\circ}C $ if the outside temperature is -10$^{\circ} C$    $ \times10^{5 }$W
(b) If the house is initially at 10$^{\circ} C$, estimate how much heat must be supplied to raise the temperature to 23$^{\circ} C$ within 30 min. Assume that only the air needs to be heated and that its volume is $750\,m^3$    $ \times10^{ 8}$J
(c) If natural gas costs 0.080 dollars per kilogram and its heat of combustion is $ 5.4\times10^{7 }\,J/kg$ how much is the monthly cost to maintain the house as in part (a) for 24 h each day, assuming 90% of the heat produced is used to heat the house? Take the specific heat of air to be $0.24\,kcal/kg$$\cdot\,C$.    dollars

  A 15-g lead bullet tra9+ cnc3o;1drj0i;y+hq t vkklveling at $220\,m/s$ passes through a thin wall and emerges at a speed of $160\,m/s$ If the bullet absorbs 50% of the heat generated, (a) what will be the temperature rise of the bullet? (b) If the bullet’s initial temperature was 20$^{\circ} C$, will any of the bullet melt, and if so, how much?    $C^{\circ} $

  A leaf of area $40\,cm^2$ and mass $ 4.5\times10^{-4 }\,kg$ directly faces the Sun on a clear day. The leaf has an emissivity of 0.85 and a specific heat of $0.80\,kcal/kg\,\cdot K$.
(a) Estimate the rate of rise of the leaf’s temperature.    $C^{\circ} $
(b) Calculate the temperature the leaf would reach if it lost all its heat by radiation to the surroundings at 20$^{\circ} $C.    $^{\circ}C $
(c) In what other ways can the heat be dissipated by the leaf?

  Using the result of part (a) in Problem 58, take into account radiation frofvt:p, c,s+bq m the leaf to calculate how much water must be transpired (evaporated) by the leaf per hour to maintbq:,psv c,+f tain a temperature of 35$^{\circ} C$.    g/h

  An iron meteorite melts when it enters the Earth’s atmosphere. If its initi f.7lc. zpu,lral temperf.zu7r l, pc.lature was -125$^{\circ} C$ outside of Earth’s atmosphere, calculate the minimum velocity the meteorite must have had before it entered Earth’s atmosphere.    m/s

  The temperature within the Earth’s crust increases about t;3wqf ) jngm,v3eq(em r im-:1.0 C$^{\circ} $ for each 30 m of depth. The thermal conductivity of the crust is $0.80\,W/C^{\circ} \cdot\,m$
(a) Determine the heat transferred from the interior to the surface for the entire Earth in 1 day.    $ \times10^{18 }\,J$
(b) Compare this heat to the amount of energy incident on the Earth in 1 day due to radiation from the Sun.$Q_{Sun}$ =    $ \times10^{4 }\,Q_{interior}$

  In a typical game of squash (Fig. 14–22), two people hit a soft rubber balle/)wel d( /x2gos ob5r6-rm io at a wall until they are about to drop due to dehydration and exhaustion. Assume that the b56deeog-m /i wlrrb)2s(o/oxall hits the wall at a velocity of $22\,m/s$ and bounces back with a velocity of $12\,m/s$ and that the kinetic energy lost in the process heats the ball. What will be the temperature increase of the ball after one bounce? (The specific heat of rubber is about $1200\,J/kg\,$$\cdot\,C$)    $C^{\circ} $

What will be the final result when equal masses of ice at 0c k+hzt61 lhmzpi7 qgs6i2 a:dz6l(e6$^{\circ} C$ and steam at 100$^{\circ}C $ are mixed together?

  In a cold environment, a pyjdp n k (b)mb+k1cdcpp+0p8 f0:ync 4erson can lose heat by conduction and radiation at a rate of about 200 W. Estimate how long it would take for the body temperature to drop + pb)d k:f1n0jpp4n yp8mck 0+(bcycd from 36.6$^{\circ} C$ to 35.6$^{\circ} C$ if metabolism were nearly to stop. Assume a mass of 70 kg. (See Table 14–1.)    s

  After a hot shower and dishwashing, there is “n1*:bj,.nml zrqdp s4yo hot water” left in the 50-gal (185-L) water heater. This suggests that the tank has emptied and refilled with water at rj lr:,n*q1pymd z4bs.oughly 10$^{\circ} C$. (a) How much energy does it take to reheat the water to 50$^{\circ} C$? (b) How long would it take if the heater output is 9500 W?    s

  The temperature of the glass surface of a 60-W lightkw *8x9 rgnoo) izzw57bulb is 65$^{\circ} C$ when the room temperature is 18$^{\circ} $C. Estimate the temperature of a 150-W lightbulb with a glass bulb the same size. Consider only radiation, and assume that 90% of the energy is emitted as heat.    $^{\circ} C$