What happens to the work done when a jar of orange juice2g0. sxcs1 p7th 8v8w q5gvk5lxg8by i is vigorously shaken?

When a hot object warms a cooler object, does 17l6ch(a 8 :s uxlahules)l1f temperature flow between them? Are the temperature chu: 1fa6ulsll) 7hsach1l e8(xanges of the two objects equal?

(a) If two objects of different temperh8b-rz ;r7 jrxatures are placed in contact, will heat naturally flow from the object with higher internal energy to the object with lower internal energy? (b) Is it possible for heat to bh -8r7j;rzxr flow even if the internal energies of the two objects are the same? Explain.

In warm regions where tropical plavq ,w3f9 imlwhc *3uw5nts grow but the temperature may drop below freezing a few times in the winter, thh q9wu*5lvw,im 3 3wcfe destruction of sensitive plants due to freezing can be reduced by watering them in the evening. Explain.

The specific heat ofq .r.k* 5dw ldu2r-kc88g huve water is quite large. Explain why this fact makes water particularly good for heating systems (thacrdg. h8v wd.q2ul*5k ru-e k8t is, hot-water radiators).

Why does water in a metal canteen ad8 )1(+gzdkqwy ff)s; swr 8gstay cooler if the cloth jacket surrounding the canteen is kept mod 8k)wd+s ( zwfras gyqfg81;)ist?

Explain why burns caused by steam on the skin 2 +) j5lces3fjfh(n quare often more severe than burns caused b35cj (2ulhsfqf+e) njy water at 100 $^{\circ} C$ .

Explain why water cools (its temperature drops) when it evaporates, using thqtp,mmghlo r/4 ip53/e concepts of latep, pmmglo4t3/5rh i q/nt heat and internal energy.

Will potatoes cook faster if the water ic8 s1b(t+b -bfzcd/6ss0uo xo s boiling faster?

Does an ordinary electric fan j 9vrn790fq/s (2exdf; tcer ccool the air? Why or why not? If not, why use it?

Very high in the Earth’s atmosphere, the temperat52u w qwpp:njk22s( qmure can be 700 $^{\circ} C$ . Yet an animal there would freeze to death rather than roast. Explain.

Explorers on failed ; fdhff ;wl zy e- ygv/7x2m9o7nap2g7Arctic expeditions have survived by covering themselves with snow7wyz 9-an7/fo2ym g2dl;; v gxefpfh7. Why would they do that?

Why is wet sand at the beach cooler to walk on than dry san hvwz;1:grw xbya +m5fyr8 :k)d?

If you hear that an object has “high heat content,” does that mean that its t5 t7ztvx dwy94emperature is high? Expla95t x dvy4wtz7in.

When hot-air furnaces are used to hea1y .run7 a3cv5iwj6nut a house, why is it important that there be a vent for air to reui5c7 j31 6var wyn.unturn to the furnace? What happens if this vent is blocked by a bookcase?

Ceiling fans are sometimes reversible, so that they drivey+z56i ues4pw l,1(o wuzoy5 7v: wikx the air down in one season and pull it up inu o zpw,v 5w:i+yw5yz7lesiok1 6x(4u another season. Which way should you set the fan for summer? For winter?

Down sleeping bags and parkas are often specified as so many:)q:noxh5x dup+ eesg y8bf 6+ inches or centimete)+5f un: 6q+x de8xpgb: oyhsers of loft, the actual thickness of the garment when it is fluffed up. Explain.

Microprocessor chips have a “heat sink” glued on top w2l,29huxnju that looks like a series of finuhxj u2n 29l,ws. Why is it shaped like that?

Sea breezes are often encountered on sunnyj+.fahk; 3o eg days at the shore of a large body of water. Explain;af ejg .ohk+3 in light 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 air can herqy2c2by 1rm86g m6flow is often cooler than a floor that rests directly on the grhe2y8y rbc 62qm1gm 6round (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 tak*-vs)w j qm;auen with the thermometer in the w- j;*muqv)a sshade.

A premature baby in an inz o2 ixu3 4uuka-1c0xbcubator can be dangerously cooled even when the air temperature in the incubator is warm. Exp x-ou20akbc1z4ux3iulain.

Why is the liner of a thermos bottle silvered (Fig. 14–s( hi b,j7xhxb3vq9f215), and why does it have a vacuum between its t ivqb9(bs2f ,hhx7x3 jwo walls?

Imagine you have a wall that 7bsi /hu7ezff ; +l5c5ki ggb;is very well insulated — it has a very high thermal resistauk f+;5z7gbsi;/lih7ce5gf bnce, $R_1$ 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) ventiliy2yyav 6z*uq92g rn)ation around edges; (2) through the frame, particularly if it is metal; (3) through they22)qzrg96 i y v*nuay 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 in detail.

A piece of wood lying in the Sun absorbs more pdn 7 or:.ul8aheat than a piece of shiny metal. Yet thpd8r.a ln7o:u e wood feels less hot than the metal when you pick it up. Explain.

The Earth cools off at night much more quickly when the weather is clear thaa 54m*n)dze hmn when cloudy. Wh* emm z4n5da)hy?

An “emergency blanket” is a thin shiny (metal cg sqhrpsij(qx+(8 4*m*i tt6koated) plastic foil. Explain how it can help to keep an immobile persons*ix8 6qt 4m+jqi* r (tghs(pk warm.

Explain why cities sitfi ni/(q.jb 0 +ql8yer b +3vswgmtn44uated by the ocean tend to have less extreme temperatures than inland cities at the samem43r8i tn/qn+l+ bvw.jeif y4 qgsb0( latitude.

  How much heat (in joules) is requiwoayh8x8;,q,j amg 1sp wk49ired to raise the temperature of 30.0 kg of wate1p8w 9 s;wmqiya, g4 ahj8okx,r from 15 $^{\circ} C$ to 95 $^{\circ} C$ ?    $ \times10^{7 }\,J$

  To what temperature will 7700 J of heat raise 3.0 kg of water that is i;j 2ll8)up rp1nsbue+nitially at 10.pjp 2 l+r18)sulub;en0 $^{\circ} C$ ?    $^{\circ} C$

  An average active person consumes abq;ck f) hu:z4pneob *6out 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)u:acftblh /u;r k )few 2+19gz is a unit of heat in the British system of units. One Btu is defined as theb1z;f :kuha 9re g/u+ )wlc2ft heat needed to raise 1 lb of water by 1 F $^{\circ} $ . Show that
1Btu = 0.252kcal=1055J

  A water heater can generatmpv756ypxpyf,rf64 wy+ i rp 64xh .yye $32,000\,kJ/h$ 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 take totk akz(hl3f2- :lmgw , heat a cup of soup (assume thi:zkk3 wl lm,gf-(2t has is 250 mL of water) from 20$^{\circ} C$ to 60$^{\circ} C$ .    min

  How many kilocalories are generated wodsi ate2-1;5 (pyuk mhen the brakes are used to bring a 1200-kg car to rest fryia 5o kpt2-e1d; ms(uom a speed of $95\,km/h$ ?    kcal

  An automobile cooling system holds 16 L of water. How much heat does it abso:a*aaqzxa1l1nr7hsb2l l d 5istz+6 ,rb if its temperature risesrq+ sh zd11saia xb56la,2 l:znl7*at from 20$^{\circ}C $ to 90$^{\circ} C$?    $ \times10^{ 6}\,J$

  What is the specific heat gz+7zx ,hduf.b,:cqy, ;n6p oe0wvon of a metal substance if 135 kJ of heat is needed to ra0,cq dyxze,fo nw6u+z,.7o :;hpvnbgise 5.1 kg of the metal from 18.0$^{\circ}C $ to 31.5$^{\circ} C$ ?    $J/kg\cdot\,C^{\circ} $

  Samples of copper, aluminum, and water experience the same temperaturbnna46mo0* uj e rise when they absorb the same amount of heat. What ijnm u*04ao 6nbs the ratio of their masses? [Hint: See Table 14–1.]$m_{Cu}$ : $m_{Al}$ : $m_{H_2O}$ =    :    :   

  A 35-g glass thermometer h 0:x; zz66zm7gw oyvj8p.)lbm oejy,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 when i8t5:jf9cztav-.q n p 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 (mass = 2my3/1es jtc4gwvc wfk3t )d +$0.4\,kg$) 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 33l fnkg 6 7rjmcu:2qx0k(7/uj f0$^{\circ} C$ 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 5w0rr vvc6fx6vfwt 0/boil 0.75 L of water initially a vwrwv 06r tf/0xvf5c6t 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 ca 3 -7v-/bah vrsfsu8usndy from the following measurements. A 15-g sample of the candy is allowed to dry before putting it in a bomb calori -b-uha rs7svu/3fs8v meter. 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 at 5)kaffvmk+k2. u(blnu vntg 0k(h *)y 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 h+clwncc:(ktm i-,-v v ammer 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 heat needed nqmxr1135i+x4;eb.m mi (cx -iian ey to raise its temperature biyqri;1. mxienb m4n3m1 xxc5 aie( -+y 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 silvk* s(n h6 4p9qykak u 2jl4ob6krjga60er that is initially at 20$^{\circ} C$?    $ \times10^{6 }\,J$

  A 0.095-kg aluminium sphere is dropped from-sn f -lfe;r4x the roof of a 45-m-high building. If 65% of the thermal energy produced when it hits the ground is absorbed by the sphere, what is ilsf4-;x rn-fets temperature increase?    $C^{\circ}$

  During exercise, a person may give off 180 kcal of heat in 30 min by evaporpar; 9 yl)cru+paji4 /ation of watepa+l cpu)/y 4r;9iraj r from the skin. How much water 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 4 k*.43wxr3dui ncr oean insulated container of liquid nitrogen4cu*e 3ndiw x4okr3r. . 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 takenx2l 4qq+9n9le 4c u4rqmu2zb9zn9u z g from the freezer at -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 kg conm ) aq.nz+ v-;s; jn(jzf(p0 esbnzg+htains 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 over the spadao9l4gfh3*5 a jj ,oen of four hours. Making the approximation that all of the cyclist’s energy goes into evaporating this water eg*o4j5alohd, af3j 9as 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 1z6+d0ekr, wnc00$^{\circ} C$ 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 merc4 bf6-nbkfkrit(wtz lk:u6 8, ury 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 travelrus s5ws0w553fr .j17f rxzgying 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 movin+o ucbs.sg(i j0i 568ey+(suixi6 xh5jixm8zg 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 investiov 4i-5mamu )ys 9qde0gator notes that the 8.2-g lead bullet that was stopped in a doorframe apparently melted compl)-q4edam9vm 5siyo 0u etely 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 kept at 460u96o 0j gsj5w qy7( sep.3fubr$^{\circ} C$ , 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 conduction in Exam+bx7zmg lr 90xple 14–10, assuming that there are strong gusty windszx b7l9mx r0g+ and the external temperature is -5$^{\circ} C$   $ \times10^{4 }$ W

  (a) How much power is radiated dfftq3u :,3 n jxqx ,e1q((vrcby a 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 of heat flows by conduction f5jrv,b/03jj, je .n baukai:prom the blood b3 r5,j/ unjj0jp,vie.: bakacapillaries 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 side, share aa08may knds;2 u; ze0g 12-cm-thick brick wall. Because of a number of 100-W lightb us;agez 20admy8;kn 0ulbs 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 +w )whfuf*/ksa 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 aluminum rod of the same length and c)nm w q;b;0qm6:h bcos/icd +aross-sectional area are attached end to end (Fig. 14–18). The copper end is placed in a furnace maintained at a cqmo wd:ca; mcb/q;+0n6h )bsi onstant 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 rateb w y66wq48wil at which the whole Earth receives energy fromw8l6w4yqb i w6 the 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 dissipated throf t wr.adss05 (kmq:4xugh a glass bulb s .kxsw :5mt0a 4(rqdfthat 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 glass?   $^{\circ}C $

  Suppose the insulating qualities of the wall of ahwq 9/o5sq6zb house come mainly from a 4.0-in. layer of brick and an R-19 layer of insulation, as shown in Fig. 14–19. What is the total rate of heat loss thrw/h69s 5o qbqzough 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 a)nicd )ao oi,,/3.q i8fftqxon air space, Fig. 14–20. (a) Show that the rate of heat flow through such a windowicoi/)o3 ,oiad,)qn.x ffq 8t 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 sh,7rw1rds12uu jppb86) zfxte6fsjo2c8 n : giould it take 11.0 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 abou n;jgck,zn 9i4t 0.20 kg 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 thery.4xnwrxj(*tdu2n-d 15 vorj mal energy is contained in the world’s oceans, estimate the heat liberated when a cube of ocean water, 1 km on each side, is cooled by 1 K. (Approx vxtn2 -njrwd1(5 *rxoyduj.4 imate the ocean water as pure water for this estimate.)    $ \times10^{ 15}\,J$

  A 15-g lead bullet is tested by firing it k::2nk+l(epx aeq *j(qdmx r2into 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 been reached, the system has a tempera*:ner2lmqx e 2p:x a +k(kd(qjture 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 it to be a l6cy5fv kiidi()7. ddz z4mr/9cac9 l perfect emitter ai9fz ()mi7r kly56 dc. lcdz /icv9d4at $T\,=\,5500K$ 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 person may a 01 m b1jft34mv7 +j7jcvdrgegenerate $200kcal/h$ 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 ofq.5kt )c vzbw0u 7y2km 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 i5utyk 0kv2 bq 7zm)wc.n the rock.    $C^{\circ} $

  A 2.3-kg lead ball is dropped into a 2.5-L insulated pail of water initbqfba s,ts/k 6iwfayo4*yt8-- u(qee ..zp8yially at 20.0s 8wu*(4.eby8eot . q6tz--faa i,ysfqk/pyb$^{\circ} C$. 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 with total su:;,d9pace/usu1q5s fjh+qnl xj k( 5jrface areajau5lujx1 5 h,qdsn e(cs k/p:q+ jf;9 $1.2\,m^2$ 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 metabo6zckwe p. jksd7x42u r- :pp(0guwk*plism 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 th/n0 er 7;:ixrhg,gkv we interior of the body to the surface. Assume that the tgrgxre/k: n, wvi0; 7hhickness 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 co,.gbv4e ex+b/yzyq 1m thick (assume conductivity of air) and a/xze qg4obye,1+b vy.rea $410\,m^2$ 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 at8m(zv ;v3 id- d1e+n l/javsql $220\,m/s$ 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 intorwdnh,pcy( o/ :l1/ nyz o2h8q account radiation from the leaf to calculate how much water must be transpired (evaporated) by the leaf per hour to mwd y /rn8lczq:n1yo,h ph/ 2o(aintain a temperature of 35$^{\circ} C$.    g/h

  An iron meteorite melts when it enters the Eala-6p 1kxci )ge pj87irth’s atmosphere. If its initial temperature was -161c8p 7xieij)gpa l k-25$^{\circ} C$ 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 ahco,3 aa* bevys)q./1j 9 ykd1.0 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 8is yw.; tlu6ssquash (Fig. 14–22), two people hit a soft rubber ball at a wall until tys6; swu8i l.they are about to drop 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 final result t; hxpzxex/ f -srw6m*-1 o3skwhen equal masses of ice at 0$^{\circ} C$ and steam at 100$^{\circ}C $ are mixed together?

  In a cold environment, a person can lose heat ob9 8u ./rc6mzv7 ruaqtgoazvv/x:g:/ s*l( oby conduction and radiation at a rate of about 200vc6/ m *so:x/tou7abvgrq8( ugva/lzo .9 rz: W. Estimate how long it would take for the body 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 in pxgf)hr b 6: js*tq/e7c15ulithe 50-gal (185-L) water h7bj gr)pu q :fxech5slt1*/ i6eater. This suggests that the tank has emptied and refilled with water at 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 surface of a 60-W lig1*rbzx5e1t gyhtbulb 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.    $^{\circ} C$