What happens to the work done when a jar o1x73bcot5 kh e l2xozhl r71d3f orange juice is vigorously shaken?

When a hot object warmd g9gy 6h2mey7s a cooler object, does temperature flow between them? Are the temperature changes of the two ob7y9edygm g26hjects equal?

(a) If two objects of different temperatures are placed in contact, wwjgje7.,r v21es*.ntqm w0cf ill heat naturally flow from the object with hiwj ns mw0rf,*7..qjee1vcg2tgher internal energy to the object with lower internal energy? (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 plants grow but the tempa,q0:jqfz 1jd9vh f8uerature may drop below freezing a few times in t1 fvj0z8q:9ah dj uf,qhe winter, the destruction of sensitive plants due to freezing can be reduced by watering them in the evening. Explain.

The specific heat of water is quite large. Explain why this fact makes water 6 jd8t*e;tsrx*vzv2f1b gv i( particde vsg*18 i v;tv6br2* xtfzj(ularly good for heating systems (that is, hot-water radiators).

Why does water in a metal canteen stay co(rhmoh c9 ; 125ayccjqoler if the cloth jacket surrounding the canteen is hacj(r5; cy2oc19mh qkept moist?

Explain why burns caused by steam on the skin are often more sj**wx f hwj3zw5.d,j6vu,c d m+o6nndevere than burns caused by water at 100 m,v+jd6wjcn j3d*n,w6*houzwx5 df. $^{\circ} C$ .

Explain why water cools (its temperature drops) when it evapora lz y5v4/)fengtes, using the concepts of eg4y l)/5zn vflatent heat and internal energy.

Will potatoes cook faster if the water is boili r,hii;-;blogoo v9c9ng faster?

Does an ordinary electric fan cool the airh /(3y 79oi n5pz0vw+ ibuayfr? Why or why not? If not, why use it?

Very high in the Earth’s atmospl* ,l,f us3(aodiufdj x2, mh6here, the temperature can be 700 $^{\circ} C$ . Yet an animal there would freeze to death rather than roast. Explain.

Explorers on failed Arctic expeditions have survive ukht;s8u p v-sph 6:h-l,7qied by covering themselves with snow. Why whst p:k il ;67uvqhp-8eu,h s-ould they do that?

Why is wet sand at th bc7ri41-ujsv e beach cooler to walk on than dry sand?

If you hear that an object has “high heat content,” does that mea ;yesm/t-q8df r sq:,gn that its temperature is hiqm;fyseq,t:- rs8/dggh? Explain.

When hot-air furnaces are used to heat a house, why is it importao(ey/pv1w z p9nt that there be a vent for air to return tow/pez 9o 1(pvy the furnace? What happens if this vent is blocked by a bookcase?

Ceiling fans are sometimes reversibl7rmau qsngout 8ijbux- (.( /3ply2m.e, so that they drive the air down in one season and pull it up i.utuj u2l(7 3paon / i(.mmgxysb8q -rn another season. Which way should you set the fan for summer? For winter?

Down sleeping bags and parkas are often specified as so many ym*vgq kac:: (g5gf(z5xc-cm inches or centimeters of loft, the actual thickness of the garment when 5*-(:aq cm gm(cxv:ggf5kczyit is fluffed up. Explain.

Microprocessor chips have a “heat sink” glued on top that looksgr 6xxrz:0pnj3a ) 1xw like a series of fins. Why is i03x6grjz xw:1 ) apnrxt shaped like that?

Sea breezes are often encountered on sunny days at the shore o - ph omq p6zimc.r:(ur5a8ze5f a large body of water. Explain in lighti (ezqhr m5 cz8pa: ru.o6pm-5 of the fact that the temperature of the land rises more rapidly than that of the nearby water.

The floor of a house on a foundation under which the airh ie0 /ljy 0q+eovhnu )5q//uyv ,a+ur can flow is often cooler than a floor iq0,v uya/r+ev ylh5h uo/ne u +/j)0qthat rests directly on the 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 takef)s 6alc*bd/ in with the thermometer in the 6c)i /afbl* sdshade.

A premature baby in an incubator ciy klm ko*:y1:an be dangerously cooled even when the air temperature in the incubator is warm. Explaik*:y:ik olym1 n.

Why is the liner of a thermos bottle silvered (Fig. 14–15), and why does it have rtx7s u* mrn6ud:.oeaj2 p8c7 a v7j eturx8d72c.as m 6p*nou:racuum between its two walls?

Imagine you have a wall that is very welha +go(z -xx qi86l ekh(7*wrzl insulated — it has a very high thermal re le 6*(hqz-kriozxwh(ag87+x sistance, $R_1$ 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) ventil9dm.as-ebsi-j 5fe :fation around 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,jsb9fd e-m f-aei:5 s. convection, or radiation? (b) Heavy curtains reduce which of these heat losses? Explain in detail.

A piece of wood lying in the Sun absorbs more heat than a piece of shiny metld 5w 1yx zlgr1:s4w1pal. Yet the wood feels less hot than the metal when you pick it up. Explain dxwwllsyp114 z1rg:5 .

The Earth cools off at night much more8g0c+abowl: c quickly when the weather is clear than when cll+0:8ca ocgbw oudy. Why?

An “emergency blanket” is a thin shiny/ur h,i r44 jnajjq515jxm4xw (metal coated) plastic foil. Explain how it can haj4 ,x5xmj r j4/45qnuwhirj1elp to keep an immobile person warm.

Explain why cities situated by8a ,5v4zuy+qy )ctyyw the ocean tend to have less extreme temperatures than inland cities at the samc8 y ,az vyw5yqu+t4y)e latitude.

  How much heat (in jouh ou9-8:qd7teh )m/dhymiw v1les) is required to raise the temperature of 30.0 kg of water from)7 :toqmm9/ei dhyhuv 1d h-8w 15 $^{\circ} C$ to 95 $^{\circ} C$ ?    $ \times10^{7 }\,J$

  To what temperature will 7700 J of heat raise 3.0 v*dt 2cwe0/ ydkg of water that is initially at 1v0cwy*2/t de d0.0 $^{\circ} C$ ?    $^{\circ} C$

  An average active person consumes about h fy101( w w)adbdwh4s2500 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 the British system*mp;dc y;oon* of units. One Btu is defined as the heat needed ;*ocndpmy *o;to raise 1 lb of water by 1 F $^{\circ} $ . Show that
1Btu = 0.252kcal=1055J

  A water heater can generate h7o,j7 d,swp1t* i*uicu w2dl $32,000\,kJ/h$ 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 350 W. Estimate how long it will tak98 r3(mg xegdse to heat a cup of soup (assume this is 250mrxe3 8 d(ggs9 mL of water) from 20$^{\circ} C$ to 60$^{\circ} C$ .    min

  How many kilocalories are generat+0qtd;.s ujtkc3ck,g ed when the brakes are used to bring a 1200-kg u3k ;g.,cqtt kcjs0 +dcar to rest from a speed of $95\,km/h$ ?    kcal

  An automobile cooling system holdsz+9) y 3 zga, d2f na*s9+savv cpjz*-ndvoh(c 16 L of water. How much heat does it absorb if its temperature rises cy9gv)*a +zd z3c2ap(jsn*d +hf z,s9a-o nvvfrom 20$^{\circ}C $ to 90$^{\circ} C$?    $ \times10^{ 6}\,J$

  What is the specific heat of a metal sub y*x3t.wv1;l /.s sf3chc6xrccn,xy j stance if 135 kJ of heat is needed to raise .wtclcyx3rjsfns3* 16x/vhy cx, ;.c5.1 kg of the metal from 18.0$^{\circ}C $ to 31.5$^{\circ} C$ ?    $J/kg\cdot\,C^{\circ} $

  Samples of copper, aluminum d8.llhst:xtu1 e)w2v, and water experience the same temperature rise when they absorb the same amount of he td)hw 1l:ux ltev8.2sat. What is the ratio of their masses? [Hint: See Table 14–1.]$m_{Cu}$ : $m_{Al}$ : $m_{H_2O}$ =    :    :   

  A 35-g glass thermomm c rs,rn7mmig)bl33 5eter reads 21.6$^{\circ} C$ 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 whv e- k9v: +:sywe svjr.-k8nroen a 245-g block of 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 (mak-nn bn6(a0uzss = $0.4\,kg$) 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 h eq*u*x4jlrqzn4 5nb 7w6se2geated to 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 cof83iir+gh sen 3feepot to bring to a boil 0.75 L of water initially an 83rg3+isihet 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 cancj7ozx -,q ug2dy from the following measurements. A 15-g sample of the candy is allowed to dry before putting it in a bomb calorimeter.jcu g-ox2, q7z 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 0va0y6g-g h3ocdojwt 79 qg,oiron 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 hammer has a sfof-(w;ssteo.gjk9 2 peed 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 then *ywc9cd8ce:jqu60 k5u om /;buo8d p:lk4xv amount of heat needed to raise its temperatur:kou d; c/y5e6cjupvl 8 cu90x* dbnkm4:8oqwe 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 to melt 16.50 kg of s+ 22s*i s4x*psfot4sie,jz zljuf+g:ilver that is initially at 20$^{\circ} C$?    $ \times10^{6 }\,J$

  A 0.095-kg aluminium sphere is dropped from (sl+ trg/ 1zbt 9ko5lothe roof of a 45-m-high building. If 65% of the thermal energyt/ot ll+r9k5 s ozg(1b produced when it hits the ground is absorbed by the sphere, what is its temperature increase?    $C^{\circ}$

  During exercise, a person may give off 180 kcsli: bzv ydw r26l/s9:al of heat in 30 min by evaporation of water from the skin. How much water has beenbs6yv z:ld:9/2ir wsl 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 insulated container of ldh, id0wd i -lf7(i(uviquid nitrogen. How much nitrogen evaporates if it is at its boiling point of 77 K and has a0 i7wu i,vd-dl( fdh(i 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 as7(snim5 y8-9 coyptxt -8.5 $^{\circ} C$ 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 kg5nprb c:ks ofhh6,rc.5k/ 3j.qyb49tiiiw - d contains 830 kg of water 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 bicyclist consumes 8.0 L of water o0 zv(:xog5f sv:knk /gver the span of four hours. Making the approximation thato 5 :kv(v0:/gxfsnk zg all 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 1007y,tmwim g.nt(l + ;sr$^{\circ} C$ 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 mercury isp/bcr(cr-t .:6 / ma nc a,l(mfnppz0u $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 travel8dc+6 cl5m1uvy 5sh qting at $250\,m/s$ 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 mlu 3/ x89cinmmyob b4n 1;za8y2eqw)soving 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 that the 8.2-g lea8toz tp,xlv006kxe5zd bullet that was stopped in a doorframe apparently melted completel5el6t 08pv0 ktoxzxz,y on 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 of 2.0 cm is oj ncau,a p(- dsqv(:wf//co2 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 hjb)53cq l2 4vr,qsui7g3 ltxp eat flow by conduction in Example 14–10, assuming that there are strong gusty winds and th7scpjl2 )q5 q,rgtl3ux vib43e external temperature is -5$^{\circ} C$   $ \times10^{4 }$ W

  (a) How much power is radiated by k/5,bum9dy f ia 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 200 W ecsska1;p im676l ak; of heat flows by conduction from the blood capillaries beneath the skin to the s71e6kk l6;mi ;aspc abody’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 side, share a 12-cm-thick brick wall.d c2plb 1l0*nh ,6zodd)+qlvo Because of a number of 100 v c2ql1o6hl* +db,lnzp)o0dd -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 Sun to melt a block of;r1i1 qmcp: gl 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 aluminum rod of the same3smd pa9zw: m9 length and cross-sectional area are att9swmz3:pd am9 ached end to end (Fig. 14–18). The copper end is placed in a furnace maintained 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 at which the whole Earth receie3+g 9tq67oz4b ljv6vxm9s cwves energy from theqvxmsl+ 3v g97j 6twoz46e9bc 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 of heat, which is dissi9mfeau( wojsvo(-rg2 ( xy: u;pated through a glass bulb that has a radius of 3.0rv:-j9o(ao2;w x gye(fusmu( cm and is 1.0 mm thick. What is the difference in temperature between the inner and outer surfaces of the glass?   $^{\circ}C $

  Suppose the insulating qualities of the wall oitj5b ren,v2heo b2n 8i-)5j w;s bbn4f a house come mainly from a 4.0-in. layer of brick and an R-19 lajbe sb2;w)54enio8j- h 5i2,vnbr b ntyer of insulation, as shown in Fig. 14–19. What is the total 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 has two panes of glass separated by an air space, F 1mcdccck9f5k4;/.njx8vp rlsy* g( yig. 14–20. (a) Show that the 8;rjvkm1 k/cy nxfc (.4ldy9 cgp*s 5crate 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 11.0 :c.jkh0kwh cq97o b)a x(0 afekg 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 tip)e3o- p g0dkg 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 is contained in the wo +ypz7b 1hp*j*( 6 eonhp0 5pkry2fgxdn.v1agrld’s oceans, estimate the heat liberated when a c* bnppgae1pxf phj(o6h ygv 0.2 *+ 71ndr5yzkube of ocean water, 1 km on each side, is cooled by 1 K. (Approximate the ocean water as pure water for this estimate.)    $ \times10^{ 15}\,J$

  A 15-g lead bullet is sk+eid 1/hjded3a m8m:v4 r *ri1zv4 ltested by firing it into a fixed block of wood with a mass of 1.05 kg. The block and imbedded bullet together absorb all the heat generated. After thermal equilibrium has: ei44 shd8rar 3e mizdvjk1+* l1vd/m 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 vb1 scd 4-htqk7bjn6)into space by the Sun, assuming it to be a perfect eq)v tj4 6b1h7kbcs nd-mitter 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 personvej,m 7 +ni*tniln05 n 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 *d yv v2n9 etr8k*zms(the top of a cliff and falls a vertical height of 140 m before striking the ground. Estimate the temperature rise of the rock if 50% of the heat generated remains in the rock. nm9st*ezr*dvk82 yv(   $C^{\circ} $

  A 2.3-kg lead ball is dropped into a 2.5-L insulated pail of 2:vg-)kzhfo, .ul,a gei0he;d gd8rq uz8 h 4rwater initially at 20.rzulf h;qkee.-gvh, a zg) 2hgo4i8dd u8:0r,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 with1as p/ld;a8bf total surface area /b1 s lafd8pa;$1.2\,m^2$ 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 metabolism rate o**.ll/ci ydwvf 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 :lp *dg z6b)cncan be conducted from the interior of the body to the surface. Assume that the thickness of tissue is 4.0 cm, c: gzb nd)6*plthat 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 thi. h m2drsern,,ck (assume conductivity of air) and areamsdr.n,e, hr2 $410\,m^2$ 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 traveling n h3mv-oh(/ioat $220\,m/s$ 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 intobc8i pd+ 9 bx1ei(rvi* account radiation from the li8x 9i1 c(rbepv* bdi+eaf to calculate how much water must be transpired (evaporated) by the leaf per hour to maintain a temperature of 35$^{\circ} C$.    g/h

  An iron meteorite melts when it enters the Eao e5 -hxy9g637brjznarth’s atmosphere. If its initial temperature way 5 3go9h6naez7xbjr-s -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 increase +g01ey; gq9y. r+ql1d mbehbls about 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/udf2h) j s33fygt y j(9is67qrk b.sc ball at a wall until they are about to rssb97(gf jdsc3f2.ky u 3 6i) jtqh/ydrop due to dehydration and exhaustion. Assume that the ball 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 fin1bc/c3nv *peual result when equal masses of ice at 0$^{\circ} C$ and steam at 100$^{\circ}C $ are mixed together?

  In a cold environment, a perv22e 9 hf7b8gh4khtz//68 fvtcll zkwson can lose heat by conduction and radiation at a rate of about 200 W. Estimate how long it would take for the bod68ezf g8/bt24tv fhcwz/k9v llh hk7 2y temperature to drop 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 “no hot water” left i p-: j(dxn73:z.wdl 6 u kweup3zja7dun the 50-gal (185-L) water heater. This suggests that the tank has emptied and refilled with water 7z:n(3 u7u d.6pjakp -:d jlwu 3zedwxat roughly 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 surfacewp5o w4ek+vwt7 t,8j dne.n7 i of a 60-W lightbulb 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.    $^{\circ} C$