What happens to the work done when a jar of 6q, uvowo 5yh5vyg8ke2zykwo5 0 9or:orange juice is vigorously shaken?

When a hot object warms a cooler object, does temperature1x*l/iuc v n0p gc6bby(5ow3e flow between them? Are the temperature changes of the two objects /uyb35i x16nleog*(0bwpcvc equal?

(a) If two objects of different temperaturesc,xy( m-f abs0 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 a y0 sbxc(-,fmpossible 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 temperature m7(rqkokz,o ;l kas +l0ay drop below freezing a few times in the winter, the destruction of sensitive plants due to freezing can be reduced by waterl ;ok7 ,klz(+saor 0qking them in the evening. Explain.

The specific heat of water is quite large. Explain why this fact makew-0e2l dhai u*si(p23v yqhj( s water particularly good fpie a0vsij2(3udqwlh(2y h-* or heating systems (that is, hot-water radiators).

Why does water in a md-jvs)qk ( mg:etal canteen stay cooler if the cloth jacket surrounding the can:j (vkqms-d) gteen is kept moist?

Explain why burns caused by steam on the skin are often more severe than b)5y qo. gkvy1hdvv,ug*1-qkg+t, wv x urns caus y1gtv ,g,o uv.*qv +v1w5hy -k)gqxkded by water at 100 $^{\circ} C$ .

Explain why water cools (its temperature drops) whelzmumr v1x:ri 7qih9,qc7c 27n it evaporates, using the concepts ofx2z,r1 iv9mq:q c 7iul77hrm c latent heat and internal energy.

Will potatoes cook faster if7z 9mug+r+ydlvt1nu2 the water is boiling faster?

Does an ordinary electric fan /4vrti 1 v 4jw 6.nuyc-d*bov.p4zltf cool the air? Why or why not? If not, why use it?

Very high in the Earth’s atmosphere, the temperature can obi0b wzc2yn*w1eg x ;6g:bd8be 700 $^{\circ} C$ . Yet an animal there would freeze to death rather than roast. Explain.

Explorers on failed Arctic expedit(y :j-ya9 v mjdev/lj8ions have survived by covering themselves with snow. Why would thj8j: de -j9a/ (mvylvyey do that?

Why is wet sand at the beach cooler b*zg1qcob i9me*,7a p to walk on than dry sand?

If you hear that an object has “hyq t*9yaf:3euei c,0g igh heat content,” does that mean that its temperature is high? Exp9yc, y t3iuaq* fege:0lain.

When hot-air furnaces are used to heat a house, why is it important that there zrd3p bfpro6;4jdd :m(- 3 uuibe a vent for air to return to the furnace? What happens if this vent i3-b3d jozum f :dird4(pr6u;ps blocked by a bookcase?

Ceiling fans are somef4f,si zi d-i(times reversible, so that they drive the air down in one season and pull it up in another season. Which wai-ifi zf( d4s,y should you set the fan for summer? For winter?

Down sleeping bags and parkas are often specified as so many inches. uw9ae5*qpfs0 jqi(w or centimeters of loftiqf qs*pu 5 j.wewa0(9, the actual thickness of the garment when it is fluffed up. Explain.

Microprocessor chips have a “heat sink” glued on d(c a5wua ct9 *0k4ftptop that looks like a series of fins. 5f9wdktp 0( a*u4t accWhy is it shaped like that?

Sea breezes are often encountered on sunny days at the shore 0h ehbuy4ul9,of a large body of water. Explain in light of the fact that the temperature of the land rises more rapidlyle 0y94uhhu,b than that of the nearby water.

The floor of a house on a foundation under which the air cjl: a -3/p3.fpemk f t(g9g4 meveewy3q,veq:an flow is often cooler than a floor that rests directly on the ground (such as a concrete slab foundation). Explain.-j,eegmeq9wp.fpmk/ :e et3(v 3:a qyfvg l43

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 the+ ro;3lpxzdu*rmometer in the shalo*+ r; p3xdzude.

A premature baby in an incubator cc,a8fa; f nspn m 70s6uivbw6 q;+ok5man be dangerously cooled even when the air temperature in the incubat+ 67obfsin p5ua8,as;k60;vcnfmqmwor is warm. Explain.

Why is the liner of a thermos bottle silvered (Fig. 14–15), and why does it hamf3ev )gm6b d)kg-*oz28 unaove a vacuu b -fnaud)ogk68mv*ez) 32omg m between its two walls?

Imagine you have a wall drqvn emz3pk.t f:f;(5)jvz 5that is very well insulated — it has a very high thermal resistance, pz rff5vjm5.z: )3 e(ndtk;qv $R_1$ 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 wind7gy,wa/ )zr: g8mrf /uat(v ciows by the following processes: (1) ventilation 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, convection, or radiation? (b) Heavy curtains reduce which of these heat losses? ri gcay( r/,vt/:fwguz 8)am7 Explain in detail.

A piece of wood lying in the Sun absorbs more heat than a piece of shiny mei hrhn,jj;d9.e lb 2y6dp6f 8ytal. Yet the wood feels less hot than the metal when yo,hhn yl.8djrje yfdb 2 i66;p9u pick it up. Explain.

The Earth cools off at night much h7rj(o*n(ge k+ekkg* more quickly when the weather is clear than when cloudy. Wh eg erkn+*g(ok(kj7h*y?

An “emergency blanket” is a thin shiny (metal coated) plastic foil. Exr a7*4wvdbjryp 4sn* (plain how it can 7 d4bas (vwp*4ry *rnjhelp to keep an immobile person warm.

Explain why cities situated by the ocean tend t.(0l7vneug )ni.v qqso have less extreme temperatures than inland cities at the same lati0 v()l. g7.qqvuisnne tude.

  How much heat (in joules) is required to raikpte w(:obd,rj43e. r (hkd+zse the temperature of 30.0 kg of wator:ebkke . zd( r+p3(dt4wh j,er from 15 $^{\circ} C$ to 95 $^{\circ} C$ ?    $ \times10^{7 }\,J$

  To what temperature will 7b vzqn3d6i-gi4tqae)gu+6qpb3 sj)7700 J of heat raise 3.0 kg of water that is initially at 10v sdi3qbz p-)gti 7 qu)eb3+ 6a6q4jng.0 $^{\circ} C$ ?    $^{\circ} C$

  An average active person consumes about 2zuvez8c(0t)8 2; v2 +fv escewmwct)oye*2 uz500 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 ofumr- qgw1c :v2 vyc/ts0a, i.y units. One Btu is defined as the heat needed to raise 1 lb of water by 0/12,:vt yi-rgqwsvyuc. c ma1 F $^{\circ} $ . Show that
1Btu = 0.252kcal=1055J

  A water heater can generataif k0cv6l +wlliq9+7 yz h9)ye $32,000\,kJ/h$ How much water can it heat from 15 $^{\circ} C$ to 50 $^{\circ} C$ per hour?    kg/h

  A small immersion heater is rjp*a8ux9p 4 qtated at 350 W. Estimate how long it will take to heat a cup of soup (a4quppa8*j9t xssume this is 250 mL of water) from 20$^{\circ} C$ to 60$^{\circ} C$ .    min

  How many kilocalories are genedw. .vomr t6b,w7 fl 59xaf5berated when the brakes are used to bring a 1200-kg car to rest from a speedlb5 7dr e9tf5fmvx 6o a,wbw.. of $95\,km/h$ ?    kcal

  An automobile cooling system holds 16 L of water. Howp9 n2b+myr/es much heat does it absorb ifsny/2 mb9p+ re its temperature rises from 20$^{\circ}C $ to 90$^{\circ} C$?    $ \times10^{ 6}\,J$

  What is the specific heat of a metal substance if 135 kJ of heat is neededfkp m,j+z) x5p to raise 5.1 kg of the metal from 1x,pz5 m)kf +pj8.0$^{\circ}C $ to 31.5$^{\circ} C$ ?    $J/kg\cdot\,C^{\circ} $

  Samples of copper, au6/2h i ycsig)luminum, and water experience the same temperature rise when they absorb the same amouy hi/c2)su6 ignt of heat. What is the ratio of their masses? [Hint: See Table 14–1.]$m_{Cu}$ : $m_{Al}$ : $m_{H_2O}$ =    :    :   

  A 35-g glass thermometer reads 21.fds i isau-a;y*(2s 6g6$^{\circ} C$ 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 r8ajll u a1kl5 33 d1yg9p:onuwhen 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 (m( 0z .jc*jzosgw*eb 3xass = $0.4\,kg$) 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 so,hm +zyawf 77ubstance is heated 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 coffeepot to e*;l; xlez-twitd4q ; -ttb+abring to a boil 0.75 L of water initile+ w;a- x; t*;ize-tdttlqb4ally at 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 following measurements. k , ra-fw a-tlffgh9ff4j3m/x3wr ((h A 15-g sample of the candy is allowed to dry before putting it in a bombfh3-xfal9,h ka(f/ r(fwfw4-r t3 jgm 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 ofnj):j d:uh+bb iron 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 avjz kk4(ijvxv r81x3/ 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 hea1k6bdo2ukf4avngs393f u 5+b:e qpitt needed to raise its temperatu56esbf ikuqd9g1u:f4b32on t 3+avk pre 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 silver that is nm jee- cn+c:r,o:5 pa(4 moakinitially at 20$^{\circ} C$?    $ \times10^{6 }\,J$

  A 0.095-kg aluminium spher*5n fcn4da mu65zj gwy1e9w) re is dropped from the roof of a 45-m-high building. If 65% of the thermal energy produced when it nw96f5)ng y d4w5a1zj*rcme uhits the ground is absorbed by the sphere, what is its temperature increase?    $C^{\circ}$

  During exercise, a person may give off 180 kf0c:jl9i3e)ivaf- aec -7 oj4r-e urncal of heat in 30 min by evaporation of water from flre in-)3rf7ivac e-c:eoa40uj 9j-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 poiy 996ahlhxjsi; 5vu*gnt is dropped into an insulated container of liquid nitrogen. How muc9gl59u* h6jxh ;vi sayh 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 fr aq,n/+ ou68ehfl .aoneezer 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 contains 830bc/hbou -e2bu wh 5kyp+ 9es-0 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 waty6 61kv)b 4knjc 2bvhoer over the span of four hours.ko1n bv6vc26hj)b k4y Making the approximation that 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 a)fk j re 5p/modmt(89wt 100$^{\circ} C$ 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 mercu z1qtr/x ku51qkjb9q,u3m 9sigys6o, ry 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 a1eai j9 uo77(t f;mfeq;kh5;c+ dayj ht $250\,m/s$ 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-skatertpwzq2a28 l* 6 nq3lek moving 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 forensi( pogc k.ock3(c investigator notes that the 8.2-g lead bullet that was stopped in a doorframe apparently melted completely on impact. o gcck(p(k.o3Assuming 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 ab;)d yv+we m84 av ttmv,3qsi r:tl6;rod with a diameter of 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 conduction in Example 14–10, assumizno n ,fj3oi,vj kx2dva/kge: 6-p 89tng that there are stroo 2 ktng-po:,kdiae6jvv9z 83 jxnf,/ng gusty winds and the external temperature is -5$^{\circ} C$   $ \times10^{4 }$ W

  (a) How much power is rek8wvlog1 w396 i b)sf/o;gz0/mso cpadiated by 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 from t -xu2y/r(*tqn qwh3e whe blood capillaries beneath the skin to the body’s surface area eu w-t/(nhy23 xrwqq *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(9(iiwrlkextec + g2pc45 r0 x 4.0 m per side, share a 12-cm-thick brick wall. Because of a number of 100-W lightbulbs in one room, the air is0(ke cprw+t4r xglicx9(2 e5i 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 ice a 93)itqbvh.4id g v(jnt 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 anda 8) (h2-qabnoyx4epdy * z:sd cross-sectional area are attached end to end (Fig. 14–18). The copper 2)d ed4 as*ho 8p(by-zxna:qyend 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 lji0x -smbkq/l 2cobp),(7 oo the whole Earth receives energy fro)pobx (2m0o/i- l,7sq ockljbm 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 heatoc3nb+u2fkex)a2: p v , which is dissipated through a glass bulb that has a radius of 3.0 cm and is 1.0 mm thick. What is the 2epa) c+bo32 :knuxvfdifference in temperature between the inner and outer surfaces of the glass?   $^{\circ}C $

  Suppose the insulating qualitigp -wj 3gw +2zp9q6stx.) v:xmqfxxm 7es of the wall of a house come mainly from a 4.0-in. layer of brick and an R-19 xs-zt .wwxf3g)qppx7+x mq:6 j9g2mv layer 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 separatedoheyqjw: :d0 rb17qu 1 by an air space, Fig. 14–20. (a) Show that the rate of heat flow through such a window by conduction id0wqoyq h:j:1ue 1rb 7s 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 takexh( b;1 7 llqq q5k+1bpw ed3ht;o9ojz 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 about 0.20 kg of liquid at .ge/2 ,hgqgtr5$^{\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 world’s oceana)a,7m npt5 tfn6oy:zb- aiv7 s, estimate the heat liberated when a cube of ocean water, 1 km on each side, is cooled by 1 K. (Approximatoa5nt a,pm-y:6 nz)77ifbt ave the ocean water as pure water for this estimate.)    $ \times10^{ 15}\,J$

  A 15-g lead bullet is tested by firing it into a fixed block of wood with a mass vzenevuaj6q7ezq m: 68c281 d of 1.05 kg. The block and imbedded bullet together absorb all naqe 7 86v8zz1mj:eq62uvcdethe 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 ;wqwupzlo47l f2vm7 / space by the Sun, assuming it to be a perfect emittermuvq ;l7o/zpw4 7f2wl 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, ;k7v2s vlw t- (iigy,va 70-kg person 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 bouldl;wvnq jgfc ,k8m n ,7de.xu.eu5j8v-er rolls off the top of a cliff and falls a vertical height o5 7cgnd lw-enuxuk8 ,f8;.e.vvj,j m qf 140 m before striking the ground. Estimate the temperature rise of the rock if 50% of the heat generated remains in the rock.    $C^{\circ} $

  A 2.3-kg lead ball is dropped inpza:c5 bht *dn;a)sq9to a 2.5-L insulated pail of water initially at 20.a cs5qhpt :z;b) *d9na0$^{\circ} C$. 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 surface a9s cy wt5/d0mbretm5/ 9scby w0da $1.2\,m^2$ 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 )sp.auxhi1x 6m+8p ah sm2fz-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 the interior of the boda/x e*(8lyax8 ,ft hsby to the surface. Assse8fx8/ b* xhla(ya,tume that the thickness 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 qsvstt f-/lwyr 366 v+2i op-hcm thick (assume conductivity of air) and are+ tvyo-hl/2v3i-qrf s wt6s6pa $410\,m^2$ 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 trav r0r4t4 wtj5veeling 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 intoyw,k:. le;brf account radiation from the lel.fr yk;e w:b,af 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 Earth’s atmosphere./1crs hiocyztue7*8 aki a9pwt68 gfr 0*96mk If its initial temperature agck u1a8hw 7yti96m*9r8 o0ktif* cz6pr/ sewas -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*m bu36p(krxzmq hk xf0vy n v)5,/q5p increases 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*8tac.kaix7mq15 u:lomds /s people hit a soft rubber ball at a wall until they are about to drop due to dehydration and exhaustion. Assume that the bksc tq/mls8.xa7:m uodai*1 5 all 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 (p69ll- qp hmjt*eys8:rhe9cl 4)b dd of ice at 0$^{\circ} C$ and steam at 100$^{\circ}C $ are mixed together?

  In a cold environment, a person can lose heat by conductionpo+ hca.t/g+qum.p g4 and radiation at a rate of about 200 W. Estimate how lon+.p u g .a/cqpht4gm+og 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, thso+zzer gw0h0 34zy+eere is “no hot water” left in the 50-gal (185-L) water heater. This suggests that the tank has emptied and refr+ 4eo+eg0shz wy0zz3illed 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 glassibwi14 gkf2q .oq16p q surface 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.    $^{\circ} C$