What happens to the work don7 vy*erzu75: t+fde- yczr ii.e when a jar of orange juice is vigorously shaken?

When a hot object warms a cooler object, does temperature flosq4 *nxs5c,0v lkidt0w between them? Are the temx5v0qt*k i0ld,ss 4n cperature changes of the two objects equal?

(a) If two objects of different temperatures are placed in contact, will heat ng j(y v,q nlus+4fur3*aturally flow from the object with higher internal energy to the object with lower internal energy? (bnfj3 s yu*ul4r,v+g(q) 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 thl0iz69cvo1pn(j m )pp3z1 lbie temperature may drop below freezing a few times in the winter, the destruction of sensitive plants due to freezing can be reduced by watering them in the evening. Exp0b oij1zppnzv)3lc9 mil16(plain.

The specific heat of water is quite large. oxg*zc6ue- s :Explain why this fact makes water particularly good for* s6c-:zg xoue heating systems (that is, hot-water radiators).

Why does water in a metal canteen stay cooler if the cloth jacket sl sko2c wqqa6j1sbqj1p7o0a u4n+76a urrounding the canteenao 0slcj1pqojaa61q6747uk+ 2bq nsw is kept moist?

Explain why burns caused by steam on the skin are often more severe than b9jpct .4xeiaco* h yobp,p+r ;+5wtc.urns caused by water;xot5i4..+ c, t*ocecapphb +pwj r9y at 100 $^{\circ} C$ .

Explain why water cools (its temperature drop3*tkecir ofqz)(j bq. n8o- g4s) when it evaporates, using the concepts of latent heat and internaln3foijq 8 -kz br. o4t(c)q*eg energy.

Will potatoes cook fastyk1 p 4hl2dan5er if the water is boiling faster?

Does an ordinary electric fan cool the air? Whd4t8)xpz oe6m- *yc cwy or why not? If not, why use it?

Very high in the Earth’s atmosphere, thebcjs47 v67d px temperature can be 700 $^{\circ} C$ . Yet an animal there would freeze to death rather than roast. Explain.

Explorers on failed Arctic expeditions have survived by covering themselves witkv5k8f p:;acqh k8qf; v a:ck5psnow. Why would they do that?

Why is wet sand at the beach cooobh2 bvn i4p20ler to walk on than dry sand?

If you hear that an object has “high heat content,” does that mean that its t8wcj +4n9k - rdr2zx uka.zm+aemperature ijxk9w.kr u+2zz4 d rc+a8 na-ms high? Explain.

When hot-air furnaces are used to heat a house, why is it imp3,wfl hzz+k i.; djjbes5 m9;lortant that there be a vent for air to return to the furnace? What 5h3sz9 wzjfd,m;ji l.;b+lke happens if this vent is blocked by a bookcase?

Ceiling fans are sometimes reversible, so that they dr3slz oyy,7pd :ive the air down in one season and pull it up in another season. Which way should you set th :od7sl,yy 3zpe fan for summer? For winter?

Down sleeping bags and parkas are often specifie kcxl4* ce;of/d as so many inches or centimeters of loft, the actual thickness of the ga ;kf4*/xecloc rment when it is fluffed up. Explain.

Microprocessor chips have a “heat sink” glued on top that loo3dh*naxl 8y5eg0n* h iks like a series of fins. Why is it sha5d g3l*h0ianx8ye n h*ped like that?

Sea breezes are often encountered on sunny mc w9d zgf/21kdays at the shore of a large body of water. Explain in light of the fact that the temperature of the land rises more rapidly than that of 92kcdf/w 1mzg the nearby water.

The floor of a house on a foundation under which the air can flow is often cnr ;c5:5chzk si(pch2ooler than a floor that rests directly on the ground (such as a concrete slab foundation). Explain2kihpz(ccr;sh n 5:c5 .

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 tt0dt: m): vvzchermometer in th 0)v mcv:z:ttde shade.

A premature baby in an incubator can be dangerously cooled even;vwpes svxikr2cf89j-e,ppn:2 b q1 - when the air temperature in the incubats19p jk cxv r8 eb:2qni -2vwf-e,psp;or is warm. Explain.

Why is the liner of a thermos bottle siz.s6rmi +zfz) lvered (Fig. 14–15), and why does it have a vacuum between its two walls? z zz+s)rmif. 6

Imagine you have a wall that is very well insulated — it h)0g3yilbri ( r;kmg4 gas a very high thermal resista y0b43mgrk(lii)r gg; nce, $R_1$ 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) dmb haf26y7jn4waxjwjo88x3f7; r 19zqjj3 f ventilation around edges; (2) through the frame, particularly if it is metal; (3) through the glass panes4jzo bwax769r273j qf8xy3 mj h8;dfj fn1a jw; 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 s+-xs2u y zl-s:xb5jr more heat than a piece of shiny metal. Yet the lb- urjs+2y s:5xxz- swood feels less hot than the metal when you pick it up. Explain.

The Earth cools off at night much more quickly when the weather bwc +(30n6ojcn ll iax+2 cq(sis clear than when cloudy il(6aq +ljwbo n0cs+xcn(23c. Why?

An “emergency blanket” is a thin shiny (metal coated) plastic fo 2tkwtwjh,)i ht- * .cee:y)piil. Explain how it can help to keep an immobilj-wy:pwi e i .c2)tk ,h*teht)e person warm.

Explain why cities situated by the ocean tend to have 3d : d6+ acdamztuqnsg* btwrk/)37l. less extreme temperatures than inl:l+b/s)z * d. 7natkd3 gctmuwd3qa6rand cities at the same latitude.

  How much heat (in joules) is required to raise the temperature of 30.4 1- zzr2g 7t9igaqx+se 8dxvv0 kg of wat27gad zr vigzxxq98-es t v4+1er from 15 $^{\circ} C$ to 95 $^{\circ} C$ ?    $ \times10^{7 }\,J$

  To what temperature will 7700 J of heat raise 3.0 kg ofy e*pwhsk g *czmbnl(s)24kx177 ts9 g water that is initially az 12hg sgsbs7(*7 4yemtkp)nc 9 *xkwlt 10.0 $^{\circ} C$ ?    $^{\circ} C$

  An average active person consumes about 2500 Cal a da+xos1z n)p p1my.
(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 heatydux3sm e-o,mh /9g:m in the British system of units. One Btu is defined as the heat needed to raise 1 lb of water by 1x e-:39m/gshd,muymo F $^{\circ} $ . Show that
1Btu = 0.252kcal=1055J

  A water heater can generate 7,8yi .th(noe cw1dl k$32,000\,kJ/h$ How much water can it heat from 15 $^{\circ} C$ to 50 $^{\circ} C$ per hour?    kg/h

  A small immersion heater is ra 5rb8l *h 2(h/hkjnc,p 6feehited at 350 W. Estimate how long it will take to heat a cup/hp6nk (e lij2hch58rf *h be, of soup (assume this is 250 mL of water) from 20$^{\circ} C$ to 60$^{\circ} C$ .    min

  How many kilocalories are generated when the brakes are( tkzo3cnrd1, used to bring a 1200-kg car to rest dk o1n,(tcz3r from a speed of $95\,km/h$ ?    kcal

  An automobile cooling system holds 16 L of water. How mj3nz,g4f *;yzr hl-bhob tm8:uch heat does it absorb if its temperature rzg bth ob j:rym4zh;l-f3,n 8*ises 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 needed to nmtmyys) cfq96:)9 rtfv5mcqhq-nq y*(,r:praise 5.1 kg of the metal from 18.0f:qthy nq9s nyr 9vpmt)mr yqc5,c*f-q 6)(:m$^{\circ}C $ to 31.5$^{\circ} C$ ?    $J/kg\cdot\,C^{\circ} $

  Samples of copper, aluminum, and water experie 22wj npmigvs7hc:2 )cnce the same temperature rise when they abso2v: j2)ncc2 hw7smipg rb the same amount 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 re g x++fj+o9:vw6thumyte0ys9/u) jxq ads 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 of copper at qgw4eg t.*(m0 iulv: o :0edis285$^{\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 a a 8-w7scb+sp= $0.4\,kg$) 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 su5 )ck8l( te epwz,jc4cbstance 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 bring to ohi+oir6(+ cm,.,n bqee+toq a boil 0.75 L of water initially e r. e,+o+c ,oqi(q minb+ho6tat 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 75l5e2 v. *lgsmt g of candy from the following measurements. A 15-g sample of the cand*25.t vsgml ley is allowed to dry before putting it in a bomb calorimeter. The aluminum bomb has a mass of 0.725 kg and is placed in 2.00 kg of water contained in an aluminum calorimeter cup of mass 0.624 kg. The initial temperature of the mixture is 15.0$^{\circ}C $ , and its temperature after ignition is 53.5$^{\circ} C$ .    Cal

  When a 290-g piece of iron atydd +7jgn3rx 2 180$^{\circ} C$ 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 sp kdvt9.uz ly,(rw 58szeed 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 neeb*1;i.;dcis 1t* f4mzg rkow eded to raise its tempei1w1 zfe dgo;*4c mk* rt.;sbirature 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 atii k8r0;n+pj/p9g hhr 20$^{\circ} C$?    $ \times10^{6 }\,J$

  A 0.095-kg aluminium sphere is dropped from the roof of a 45-m-hi rkld9;b16 kot)g ruo+gh building. If 65% of the thermal energy produced when it hits the ground is absorbed by the sphere, what is its temperature increaorlrbk utog9)d6k +1;se?    $C^{\circ}$

  During exercise, a person may give p*c b6 s21gtk 5gjae.tlx0,bkoff 180 kcal of heat in 30 min by evaporation of water from the skin. How much water has been loet2gtbga , j0ks5. pl 1c*kbx6st?    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 p9t+.jj wvovveo9 (3a ob6x,l(m o5jhaoint is dropped into an insulated container of liquid nitrogen. How much nitrogen evaporates if it is at itsomo t.jo3aa9 (v(h xjw bj6v eo5l,9+v 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 3f .kb nao,sp+j.v4gvthe 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 18/h3yhs9g 3u iu2z*/rhv)dwn w $^{\circ} C$. 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 n8d5ro -m1cd4pqrvop;cpi3l(qw) w ( consumes 8.0 L of water 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 is only about 20%, most of the energy consumed does go tropi;cc1 5p(8dn)rowdqw( v43 p l q-mo heat, so our approximation is not far off.)    kcal

  What mass of steam at 1009ny ed40xyv3: l3gukwp,v vs3 $^{\circ} C$ 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 mercur(ty-sa.sx( nyyu l35sx p; 4fry 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 )vldbx hp);f3 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-skatert4j6 1-+rxar;uf nifh 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 forensic investigator notes that the 8.2-g lead bullet v ky17rot43a+-l zu.r-hplm gthat was stopped in a doorfra3u.o+m 4h lp-z17y- grktrl vame apparently melted completely 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 aluminum0axr.zdl .mea ygmkvk4e n*d,t ;i-7( 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 hea* 9awp.yrnr*i 2q/e olg;eqk bq1/ih/ t flow by conduction in Example 14–10, assuming that the /oqwq; rhy* leb9p/rn*i/ kg.2qai 1ere are strong gusty winds and the external temperature is -5$^{\circ} C$   $ \times10^{4 }$ W

  (a) How much power is radiated by a tungsten sphere (emis(dd2(t9ppzx e sivity $e\,=\,0.35$) 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 conducti1v8ayu1eod furj+x + 2on from the blood capillaries beneath the skin to the bodv y xuj2d1+1aufe+ or8y’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 p:j s*1tzoit lkr-f -*her side, share a 12-cm-thick brick wall. Because of a number of 100-W lightbulbs in one room, the air is at 3:h -lzoit *kt-1fjr s*0$^{\circ} C$, 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 bld0/ygis j v)a5n+ 8:s mk o.fbrqiev-+ock 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 cross-sectional area ag,cmip9r.c /f x drvmx (l+3p;re attached end to end (Fig. 14–18). The copper end is placed in a furnace maintained at a constant tempevxg,l +/ 9fc rmmrc(dp.x3 p;irature 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 whicse.*mje 1 vfhergb0:2h the whole Earth receives energy from the Sun.:.ef*meg v0 e2jsrb h1    $ \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, w,;;0y)u3onglnh g 3h ) uuqyvqhich is dissipated through a glass bulb that ha uy3vuog)lnn ,hquyhq03 g;);s 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 a h ;qit /j3vbwm5 p84fqgouse come mainly from a 4.0-in. layer of brick and an R-19 layer of insulation, as shown inf ; /5mgb3p4wqit v8jq 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 spac8vh(u jn2 iz04nm dv2oka6rc3e, Fig. 142( dz6vru v jh2m4nnoc8i3a0k–20. (a) Show that the rate of heat flow through such a window by conduction is given by
$\frac{Q}{t}$ = $\frac{A(T_2-T_1)}{l_2/k_1+l_2/k_2+l_3/k_3}$,
where $k_1$,$k_2$ and $k_3$ are the thermal conductivities for glass, air, and glass, respectively. (b) Generalize this expression for any number of materials placed next to one another.

  Approximately how lonywtz h0 2trj/35cft 4jg should 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 contait wdxv48cq02;dft(*b p 6zmy gns about 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 therm0tets*hsu y4 demmc or)4p qmv 1 +l7u:a;,tu5al 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.o*q sdm tu 4r41tch;0et,+mveuu5psy)a:7 m l (Approximate 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 gp,p+j f2tq2,b .p:zwzay-if 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,zgyp . b:q-wt, p+i2,z ffaj2p 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 spa12n h xg)w*xtzce by the Sun, assuming it to be a perfect emitter at *z1w2n xhg tx)$T\,=\,5500K$ 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 generate 47tf3 tuu mi ,bx3ld3e$200kcal/h$ 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 height82s ceclr-l nmvu:w: 2n5x i3i of 140 m before striking the ground. Estimate the temperature rise of the rock if 50% of t5-2xnv llcs2 m wi :8uec:3nrihe heat generated remains in the rock.    $C^{\circ} $

  A 2.3-kg lead ball is dropped into a 2.5-iuby r 4-j2 fb2u8,hgjgu )hh*lq*r 3hL insulated pail of water initially at 2uij2grub)*8 4*hrlub qhgyh,j h2f-30.0$^{\circ} C$. 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 wittf euhe7+c,o :tyz (v;h total surface area oeft:+(zey,7;tvuch $1.2\,m^2$ 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 mecu9dh7zebt 678:v nkbtabolism 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 conduct xlhvc w+4ike)uzw;/ *ld()o xed from the interior of the body to the surface. Assume that the +wl(*lxuz/d4;v we)c hoi xk)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 cmumhr)w u0krhh qzh4p4dl/ 00, thick (assume conductivity of air) and ah40hhqlp 0 urdw4z0,u/kmh r)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 at-emtefg3r.e/pvqg 34 $220\,m/s$ 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 ea ky- ;a ,z)/h6wpg6lxbs b9mbkx(g958, take into account radiation from the leaf to calculate how),6a 9s b-hexl(gw9zby/km kba; g6px much water must be transpired (evaporated) by the leaf per hour to maintain a temperature of 35$^{\circ} C$.    g/h

  An iron meteorite mels 2jlzkt78lln)hjd1* ts when it enters the Earth’s atmosphere. If its initial temperature was jl*h)1s2dk7lnzl8 t j -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 E8wxkdl e ,8r8kvfs :8qe4 j2rgarth’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 pedymj i /ov0vos ;7h/b0ople hit a soft rubber ball at a wall until they are about to drop due to dehydration and exhaustion. Assume that the ball j/0o; smiy/7hv0 d bovhits 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 zwsq qkf9rp 5 -i .oz(y;:g1zfmasses of ice at 0$^{\circ} C$ and steam at 100$^{\circ}C $ are mixed together?

  In a cold environment, a person can lob+1vie g6 sxv5b(.php se heat by conduction and radiation at a rate of about 200 W. Estimate how lon5h6p e+(1 vv bbgipxs.g 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 dishwas(xbx (d4j0tffj ) g:ix vuq1(hhing, there is “no hot water” left in the 50-gal (185-L) water heater. This suggests that the tank has emptied and refilled with water attg0h:x(()1ff xubjji( dq v4 x 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 k)ovg7(f)oe t 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.    $^{\circ} C$