What happens to the work done when a jar of orange juice is q ahzq0g)2n1kqpy6 yt57wo , yvigorously shaken?

When a hot object warms a cooler object, does temperature flow between them? Ar5:cf5zckh5 ie e the temperature changes of the two 5 55fzch:ckeiobjects equal?

(a) If two objects of different temperatures are placed in contact, 6 irom7kp1)tmwill heat naturally flow from the object with higher internal energy to the object with lower internal energy? (b) Is it possible for heat to f6irp1o kmm7t)low even if the internal energies of the two objects are the same? Explain.

In warm regions where tropical plants grow but the temperayurpim;; z*7iwx 2a2y ture may drop below freezing a few times in the winter, the destrucu22 i7r;wy amy p;ix*ztion of sensitive plants due to freezing can be reduced by watering them in the evening. Explain.

The specific heat of w7mx+ qdkj-,;c 2gs tlaater is quite large. Explain why this fact makes water partic2+qatj ; sgl-dm7 ,xckularly good for heating systems (that is, hot-water radiators).

Why does water in a metal canteen stay cooler if the cloth jacket surroj2z+ p+ozfsk+ unding the canteen is kept mjz+2+s f+zokp oist?

Explain why burns caused by steam on the skin are often(4 suk2w mzuua1c 6v4i more severe than burns caused by water at 1a2(iu6kwuvsz14um 4c00 $^{\circ} C$ .

Explain why water cools (its temperature drops) when yol tqc +4/:eqny;;8b6 mjvy jit evaporates, using the concepts of latent hcmy8qe yv+; bqy:tn/ljo4j 6 ;eat and internal energy.

Will potatoes cook faster if the water is bt)ic/2)pu73 ayuqj kqoiling faster?

Does an ordinary electric fan cool the air? Why or why not? If not, wh qt 1tb x.c;ds r9se3+1gtqia1y use it?

Very high in the Earth’ n zx*p2g6.f/av6t3tausfni0ye lqto60 w x-7 s atmosphere, the temperature can be 700 $^{\circ} C$ . Yet an animal there would freeze to death rather than roast. Explain.

Explorers on failed Arctic expedi4s1qt r 5ztjb5puz ku e;5y76qtions have survived by covering themselves with sne574ztuqs5 5yb1rk tpj6 z;qu ow. Why would they do that?

Why is wet sand at the beach cooler to wa.1i jy2gfdetn 1:ge i6lk on than dry sand?

If you hear that an object has “high heat content,” does that mean/(efqfoq(5.dja*o lh )l b7qo that its temperaturb 7)*qllooq/ jfdofea5( (q.he is high? Explain.

When hot-air furnaces are mh0qq6g aw4d;used to heat a house, why is it important that there be a vent for air to return to the furn40aq ;q6 gwhdmace? What happens if this vent is blocked by a bookcase?

Ceiling fans are sometimes reversible, so that tul jjl mg p0f*7x5jq0hw,jr:*hey drive the air down in one season and pull it up in another season. Which way should you set the flr*f pl7j0 uh:wxgmjq*5jj0, an for summer? For winter?

Down sleeping bags and parkas are often specified as so many bec 62mkplq*:inches or centimeters of loft, the actual thicknes:qecp2 *bmkl6 s of the garment when it is fluffed up. Explain.

Microprocessor chips have a “heat sink” glued on top that loftk2k,u dhp/o78 dgef0 c wpj 8e4vj1(oks like a series of k,j4u7 p j8f8e dev h2tf ow01gk(cp/dfins. Why is it shaped like that?

Sea breezes are often encountered on sunn- vduiiu/ 4s686llxfvo5i xqok:c .( oy days at the shore of a large body of water. Explaiov.(6u i4xk/o os5l: fd q6icuxlv -8in 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 flow is often cq- psqi 2/sd.qeu4./9q+ meip/ssbesooler than a floor that rests directly on the ground (such as a concrete slab +4. q 9ps /sidessq-2.eq/sipm ue/qbfoundation). 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 i:/ d8mi ssl:wvn the sha 8:vs/isd :wmlde.

A premature baby in an incubator can be dangerously coziax ef4/i;g nahy lq)w) 0w7*lyco7*oled even when the air temperature in thef q4hc; lz elao7inw w/)*a*ig7y)x0y incubator is warm. Explain.

Why is the liner of a thermos bottle silvered (Fig. 14–15), and why does ims ux3)z/dacupxz,y :)63hynt have a vacuum between its two walls?dy)px) c6um xa 3zz:snu /,hy3

Imagine you have a wall that is very well insulated — gju so+ zett ej7r*6i:xg7o//it has a very high thermal resista*/+/eo:j szgtxi o6ut7 7r jegnce, $R_1$ 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 followiimofw/u9p*dd9:tp0 i ng 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 curt9 idowft/pp m0* :i9duains reduce which of these heat losses? Explain in detail.

A piece of wood lying in the Sun absorbs more heat t9 p 5t bsv3c re;*0gaff+xyi:hhan a piece of shiny metal. Yet the wood feels less hot than the metalif0+3:*fsvx a;tc ygbr 9p5he when you pick it up. Explain.

The Earth cools off at nightb2jqf 5a/j -egd9 d/hx much more quickly when the weather is clear than when cloudy. b hdf2ajx-/jdeg/9q 5 Why?

An “emergency blanket” is a thin shiny (metal coated) plas4 q*ph /go(zifsn+0totic foil. Explain how i0o/io nzpqgs f+(ht4 *t can help to keep an immobile person warm.

Explain why cities situated by the ocean tend to have less extreme teh0:8o 9um:hma 2*)s,uuaxosx+,lpbqr gfp *amperatures than hp, pb *9h:*arx,xo:osa 8maugslm+f 02 u) quinland cities at the same latitude.

  How much heat (in joules) is require,(lpbdlwq a+. i(e9z ad to raise the temperature of 30.0 kg of water(i.z,pq aldwal( be9+ from 15 $^{\circ} C$ to 95 $^{\circ} C$ ?    $ \times10^{7 }\,J$

  To what temperature will 7700 J of heat x3.p 5kxtl8b jraise 3.0 kg of water that is initially at 10.0pxlkj8xt53 b . $^{\circ} C$ ?    $^{\circ} C$

  An average active person consumesvasx )2:3 gjim 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 the British system of un4;j)x,yxmse rits. One Btu is defined as the heat needed to raise 1 lb of water,e ;sj4xm)x yr by 1 F $^{\circ} $ . Show that
1Btu = 0.252kcal=1055J

  A water heater can genera7+3 ky;d ug3tw a2dl93diolhrte $32,000\,kJ/h$ 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 to he38mqt2;hiz .k:lr n za xy(/7u9ohfueat a cup of soum3rhz:7.2 u;nt(ihou 9kl/fy 8 ex zaqp (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 bring 5)kvi(z 7x pn.ezdvy7 a 1200-kg car to ()7pevdv5zxzi 7. nykrest from a speed of $95\,km/h$ ?    kcal

  An automobile cooling system holds 16 L of water. How muchhq :/bxdnep 7 c1*o8we heat does it absorb if its temp1:dbh ewnp87c* xqeo/ erature rises from 20$^{\circ}C $ to 90$^{\circ} C$?    $ \times10^{ 6}\,J$

  What is the specific heat of a metgav;hi 8;s x7id17rf pal substance if 135 kJ of heat is needed to raise 5.1 kp; ahi7r; g x7d8vi1sfg 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 tem d7ayna )r-o:kv8wn:wperature rise when they absorb the same amountn8 d v:aon)w7: kyraw- 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 thermometejddx pagv/ qf 3egw 3(mg649s:r 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 a 245-g block chvd.a7y)v t ;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 (mas4wr3ah 4imud- s = $0.4\,kg$) 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 mh,i5rxz6jg *+ fs(q14vtx pato 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 coffeepspk;v+jd*o b7gxbt 77ot to bring to a boil 0.75 L of water initia 7+bokt j7x*spd g7bv;lly 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 followinc- dn nl0:4 ymm :fm+cw4,dqakg measurements. A 15-g sample of the candy is allowed to dry before putting it in a bomb calorimeter. The aluminum bomb has a mass mca:k:l mqmc0yn wfd,4-4dn+ 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 iron1kp6 x+u qftw*c2r5sb 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 speed vob369yroir9o ze o( -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 ae bj7aga7hhx8 c/l-q)n object is defined as the amount of heat needed to raisea eg8ajq7)bh7c-h lx / its temperature 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 initially at 20of1y5ivx0oa; ) e+g uo$^{\circ} C$?    $ \times10^{6 }\,J$

  A 0.095-kg aluminium sphere is drou34v.nl: xwooe .h+tm qwy;kc q /jh(,pped from the roof of a 45-m-high building. If 65% of the thermal energy produced when it hits the ground is absorb(k h 4xhwmcoj/,u. l .w:vyon+;tq3eqed 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.++4bt lr rzgs evaporation of water from t.rs z4+tl+g rbhe 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 mwn)3wisi t w404 hnbk5elting point is dropped into an insulated container of liquid nitrogen. How much nitrogen evaporates if it is at its boiling point of) 4 nbwkn40swi h35wti 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 fr5rw/pn7ozi*o om 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 contains 830 kg of water at 1ya:pni(/ 5kc vun/ q:,yih 6ue8$^{\circ} C$. 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 xxf7 vq+-ajsu7a*u/85k ftniy v- :yqwater over the span of four hours. 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 *iuuvsy /75fvfnx -q x-kqtaa +j7:y8is 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 100:g-uoj hza(:p $^{\circ} C$ 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 meruo uyi-sdhh.dx3,2j- uhzk*1yx77 vqcury 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 a *yxsm/v5 ubm7t $250\,m/s$ 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 mo v5b 3:cg2qldlving 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 hqoat-1qu3+ eif,z;m zw+g8d the 8.2-g lead bullet that was stopped in a doorframe apparently melted completely on im+1fhi8m,q+ -o 3z d;uqtwe gazpact. 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 diametenk3e x 3rtp2)lr 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 con.wj p0vbr:7p 3l tv8mtduction in Example 14–10, assuming that there are strong gusty winds and the external tempp ttwr b0vjlv73 p:.8merature is -5$^{\circ} C$   $ \times10^{4 }$ W

  (a) How much power is r. gp5yjmrqdp9l86xb: adiated 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. el/ mys;iygd;u fi0p8 esh 3l5 g92n3mSuppose 200 W of heat flows by conduction from the blood capip3 ee my0s i;df2 g;5uygn3islh98l/m llaries 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 a 12-cm-kqkv1cm+*cyq.l+ m v 8thick brick wall. Because of a number of 100-W lightvk+c 8q1 +m.kcmqvy *lbulbs 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 takeyug2 f(2m3jmq the Sun 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 aluminum rod of the same length 5uer- ila7i9(z s4vj land cross-sectional area are4 u 9 e5jla-(lrs7vizi attached 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 which2xbk 1fxzfq k xh*2n9- the whole Earth receives energy from t b9kf1 qxfnz -2xk*2hxhe 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 dwns5u k;g; 4wry9*kb h n-ork7issipated through a glass bulb that has a radius of 3.0 cm and is 1.0 mm thick. What 9u y h7rkw5knonrwk;g-b4; *sis the difference in temperature between the inner and outer surfaces of the glass?   $^{\circ}C $

  Suppose the insulating qualities ayvw rujdnf)/g(r) 9-85 mleydi: 3csof the wall of a 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 totaewn: ))jvsarf-lcy839 uy/idrd5(gm l 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 separat b ok+2c 1 oqksqtwub-0zz:,o+ed by an air space, Fig. 14–20. (a) Show that the rate of heat flow ,q2s+1 +tobzub kqc:0o w-zok 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 kg of /u liy2yxl8:jice 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 abdfunz :6d jzk1l1ke4o6 y*nb +out 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 thermal energy is contained in the world’s oceans,g* ;rezp1e1i (to2mbj estimate the heat liberated when a cube of ocean water, 1 km on each side, is cooled by 1 K. (Approximate the ocean water as pure water for this estimate.) 2 gob m1p(1jreie*z;t    $ \times10^{ 15}\,J$

  A 15-g lead bullet is tested by firing it into a fixed be;*+ hn xy:x ouw5)ligt ftj;,lock of wood with a mass of 1.05 kg. The block and imbedded bullet together absorb all the heat generated. Afte fl;w:x +y*gie) thotu,;nxj5r 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,z9y n ++qs u5cyzdh5 x7t*fpy7 assuming it to be a perfect emi9u 5zyxtnq7 7ypy*fh+dsc 5z+ tter 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 person maewo3 hlulklrc4 3e3d:f s f1;:y 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 heigjvlk25 xu(l q9x: df5wjx p*rv(u3mw) ht of 140 m before striking the k5q )vrwfxm:d(xul92ju(lwp v 5* j 3xground. 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 into a 2.5-L insulated pail of water initially atwtt(ksgl :0i7vudb3pz8 e./,q tu5 0iiyv bz8 20(edbt 0ip,v/ iw7 qvzgiz85 :u3ulkbt0t8ys..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 with total surface a2s;f: odr0 kuhreas0u;:hr fokd2 $1.2\,m^2$ 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 hap:;ueprx u8fcagm9 t:a 6c0snc;-+cvs an average metabolism 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 mjz9w6 oohh9hj.9e6ce interior of the body to the surface. Assumzh oc9o99h6j j we6mh.e 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 cm thick (assume5ewguv76oxdm6c o yw;kj2;9 l conductivity of air) and arw7e;xv dgu69 2 ;lkoyom6wj 5cea $410\,m^2$ 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 travelingwv/k)evb:z vqg z/r05 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 accounts770vhe ;gjm*kyr* lr9awgu4 radiation from the leaf to calculate how much water must be transpired (evaporated) by the leaf pelh;u 04rggvejw*skya7mr9 *7r hour to maintain a temperature of 35$^{\circ} C$.    g/h

  An iron meteorite melts whtmo7bm;b 7q- bm+o;xj-8poax en it enters the Earth’s atmosphere. If its initial temperature wax;-7tmm7bm a qjpbo;-+bo8 xos -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 uc;n3dwzi dp2c1(i t8the Earth’s crust 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 *v:5vxx3 wa-qmraf7 speople hit a soft rubber ball at a wall until they are about to drop due to dehydrat7xr:svaa5vm3 wx fq*-ion 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 when equal masses of ice+wk8jeg*:xs cao2r.l at 0$^{\circ} C$ and steam at 100$^{\circ}C $ are mixed together?

  In a cold environment, a person can lose heat by conduction and radiation at kiibre8:d-/-l q6 mfc.jy ckp6c+q (fa rate of about 200 W. Estimate how long it would take fi r: j6m-+by qe6 cff-icl8.dc/kk (qpor 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 isga z/jckxyjg *m*db+(f:9b r ;k8;fvn “no hot water” left in the 50-gal (185-L) water heater. This suggests that the taf;*jz;k/yg ba9n x+(gfb *jcr v8 dk:mnk 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/ytpq() ozj; z+u)y)xizwz:w 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.    $^{\circ} C$