What happens to the e ry*5qt1(hmd work done when a jar of orange juice is vigorously shaken?

When a hot object war5md br/t b77pfms a cooler object, does temperature flow between them? Are the temperature changes of rfp/dbm7t7 b5 the two objects equal?

(a) If two objects of different temperatures are placed in contact, will heat naayrpd28z , ft1pl 4n;hdl1gg.turally flow fro ;p 2l84pgldn.rhy a1 ,tdg1fzm the object with higher internal energy to the object with lower internal energy? (b) Is it possible for heat to flow even if the internal energies of the two objects are the same? Explain.

In warm regions where tropical plants grow but thn.ryv(g*4 1z/9v i iq.ixo hcze temperature may drop below freezing a few times in the winter, the destruction of sensitive plants due to freezing cnvcx*iy4vh ir 1qg/. 9i .zoz(an be reduced by watering them in the evening. Explain.

The specific heat of water is quite large. Expr uy)fxt55x9ano i5i7lain why this fact makes water particularly good for heating systems (that is, hot-water radiators)u59ax iyifxrn 5)57t o.

Why does water in a metal canteen stay b6mv ,ust5ux7 cooler if the cloth jacket surrounding the b 7tu 5su,vx6mcanteen is kept moist?

Explain why burns caused:rf7o+on.pc g by steam on the skin are often more severe than burns caused by water crp gn+:7fo.o at 100 $^{\circ} C$ .

Explain why water cools (its temperature drops) when it evapo*pv-bg(t 7cetw :h1x+f1djacrates, using the concepts of latent heat and internal enevjcwb*1f-te + : g(1dapxh tc7rgy.

Will potatoes cook faster if the water is boizypo-e)rb dwx8/ nym2u( ;oik y2(6xf ling faster?

Does an ordinary electric fan cool the air? Why or why novd:6uo qusx5 p0rmk; q tgl2/*t? If not, why use it?

Very high in the Earth’s atmosphere, the temperature,qhns3:xb14lf( zoo k can be 700 $^{\circ} C$ . Yet an animal there would freeze to death rather than roast. Explain.

Explorers on failed Arctic expeoa:*1- ktefovditions have survived by covering themselves with snow. Why would they do tt1-k* :eoafovhat?

Why is wet sand at the beach cooler to walk on than dry sa aauv :ilst :t-:w4-mpnd?

If you hear that an object has “high heat content,” does that mean that its tem-(:ldlzss s4)ktjt7dfa 84 v iperature is jvd(44lsdk7tt)f l :is- as8 zhigh? Explain.

When hot-air furnaces are used to heat a house, why is it important that ther;*fvib2k4b l oe be a vent for air to return to the furnace? What happens if this vent is blocked by a bo 2;kib4 obv*lfokcase?

Ceiling fans are sometimes reversible, so that they drive the zr,n52h fsryi, pu/( sair down in one season and pull it up in another season. Which way should you set the fan for summer? For winf(s/,nuiy,5z 2rphsrter?

Down sleeping bags and parkas arpivua-1a*nic7anbcukh : , 9 4e often specified as so many inches or centimeters of i4bv*uana p9c1, ac i-un7h:kloft, the actual thickness of the garment when it is fluffed up. Explain.

Microprocessor chips have a “heat sink” glued oh pwy2m;d)-jg u9( rub8mdej+n top that looks like a series of fins. Why dd-b2 8;(j9ypjue+grumw )hmis it shaped like that?

Sea breezes are often encount ,c0gmkrsbr*7ered on sunny days at the shore of a large body of water. Explain in light of the fact that the temperature of the land rm,rs0b7c*k g rises more rapidly than that of the nearby water.

The floor of a house on a foundation under which the air can flow o-dv*cvj 4n sx 0:)v:p4inv 8*jotxjkis often cooler than a floor that rests directly on the g *pk v4dv) nt-sjox n8i*j0vx:o v:jc4round (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 taken with the thermorj*4b/p8/dxd 6m ajh rmeter in thj*rx 8dpjab6r//dm 4h e shade.

A premature baby in an incuba*zj o phgww6( 5:npi,gtor can be dangerously cooled even when the air temperature in the incubator is warm. Expj(ihong p,:6 w gw*pz5lain.

Why is the liner of a thermos bottle sil88(d+tjs yx2scmv s i q48-uzgvered (Fig. 14–15), and why does it have a vacuum between its two wal8ssmz+xd c(vs-2qugi84jyt 8ls?

Imagine you have a wall that is very well insulated — it has a very hihu3as r) (9vv5(o0pgc)s+ hgwftaz pe) pj.(qgh thermal resistanv )5vpsg (ph)qu(0az t o3c wpjs.ef(h9rga)+ce, $R_1$ 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 t c9 9f /.hk p9bwtkd yb:1a-agjb ,b,fpmb*/ezhe following processes: (1) ventilation around edges; (2) through the frame, particularly if it is metal; (3) through the glass panes; an9acb,/.pkhz91kbjb d: yp bbm, f*/g-t9wfead (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 th nly+ a7)8t xr. o:jjewsb0xl6e Sun absorbs more heat than a piece of shiny metal. Yet the woodnylaexb)t x+jj86sr ol 70w: . 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 than whvz6ixfk.d 4e35mg 9e elm1. tjen cloudy. Whez 19 6 5gfiv3k4jm .mdetlxe.y?

An “emergency blanket” is a thin shiny (metal coated) plastic foil. Explam-e )jrkv/2b rin how it can help to keep an immobile person) /r2e vj-kmrb warm.

Explain why cities situated by the ocean tend to have less extreme tempetm5 mfe :sr:9iratures than fi 59m::et msrinland cities at the same latitude.

  How much heat (in joules) is required to r vk)9h lmfd c)u05tths d)(fc*aise the temperature of 30.0 kg of water) uh *(cfc)sf vhl5k)t9dm0td from 15 $^{\circ} C$ to 95 $^{\circ} C$ ?    $ \times10^{7 }\,J$

  To what temperature will 7700 J ofn/ o-wb pfxe8- heat raise 3.0 kg of water that is initially at wep/x8o-fb-n 10.0 $^{\circ} C$ ?    $^{\circ} C$

  An average active person consumes about 2500 C mh-,1ucbkvg: al 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 sy t1r:t6ro tb xe1py9w(stem of units. One Btu is defined as the heapr ert9ttx1b:yw 6 o1(t needed to raise 1 lb of water by 1 F $^{\circ} $ . Show that
1Btu = 0.252kcal=1055J

  A water heater can gene ;tc o4gk/:uw1loogrr b3n3 *drate $32,000\,kJ/h$ How much water can it heat from 15 $^{\circ} C$ to 50 $^{\circ} C$ per hour?    kg/h

  A small immersion heater is rated a/3 oas 0yp(a6qw0z 7y7di/ xpwlox; nnt 350 W. Estimate how long it will take to heat a cuq(l;7zx3a/0wan0w/n po yyis7 doxp6 p of soup (assume this is 250 mL of water) from 20$^{\circ} C$ to 60$^{\circ} C$ .    min

  How many kilocalories are generated whebh9cb6t7;bdbv km- 8u n the brakes are used to bring a 1200-kg car to rest from a h7k; -8 bbcbmvb6d9tuspeed of $95\,km/h$ ?    kcal

  An automobile cooling system holds 16 L of water. How much heat ppc1f6a*isl7 p(y ph6does it absorb if its templ fy1h(s6ap6pp7*c i perature 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 ga/7m /qt-9 ,qquq uguneeded to raise 5.mu 7qg,q tq/a9quu g/-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 temperature rise whenno wz70, tnry-h ;9gza (gnmy5vf u++z they absorb the same amount of heat. What is the ratio of their masses? [Hint: See Tam-+ gr;(t n,u0+zzg ny9vaywo f5hn z7ble 14–1.]$m_{Cu}$ : $m_{Al}$ : $m_{H_2O}$ =    :    :   

  A 35-g glass thermometer reads 21.6w xv. y cyugx(d74/1kn$^{\circ} C$ 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 equilibe aco8r,sir224ssi k 9rium temperature when 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 horseshoeaf ai1e,ovk m)aj84:t7mpix- b 8aq 3u (mass = $0.4\,kg$) 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 3d: n0)draq 1us: js9l3g r -x7zdq8jtg30$^{\circ} C$ 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 boil 0.75 L of wateeo1zy8e j zn5 (f+1s0aak4es xr initially +sfy xo8z1ejae51ks4z (0n ea 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 candyrwkigm03h3b - e5q6b)gu.0adikjw lw w77qk; from the following measurements. A 15-g sample of the candy is allowed to dry before putting it in a bomb calorimeter. The mhqk. iu wg 3bbkwlkd763eiq 5 ;7rjw)-w00agaluminum 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 ir nyhjfjd 6uow*r:qs/(,f *7p don 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 h/v;7bgw w /i3mij bglu),lz oo k4g7w0ammer 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 )vc*m3dvj 2zcpsmbiqd qw:4:6u oky0 s1 6op(is defined as the amount of heat needed to raise its temperature by 1 kb*z :mqc6) d4oujdm13(2w i c06 vvqssy:ppo $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 kgmj -d7 +v 3fmwup88vjg of silver that is initially at 20$^{\circ} C$?    $ \times10^{6 }\,J$

  A 0.095-kg aluminium sphere is dropped from the roof of a 45-m-hqtj+ md ,njm;-igh building. If 65% of the thermal energy produced when it hi mnj ,q-dtjm+;ts the ground is absorbed by the sphere, what is its temperature increase?    $C^{\circ}$

  During exercise, a person may give off 180 kcal of-yw,ey um-vyco1ursy17 5 c4 r heat in 30 min by evaporation of water from the skin. How much water has been l es ur7u1-my1w5r4-v,coc yyyost?    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 poin *e ax4zb+9nfg(dmu+wt is dropped into an insulated container of liquid nitrogen. How mm aguw(e* +d9zb+ x4fnuch 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 titmhtk880ec(qsi) 8) o4)/igxq.+jc btdj zlhe 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 contan)6:0 iqql dirins 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 bicymbj z1cp mv3+.clist 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 effi.pvzjb m+ m13cciency 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 1 6qkyu.a.bd *b00$^{\circ} C$ must be added to 1.00 kg of ice at 0$^{\circ} C$ to yield liquid water at 20$^{\circ} C$ ?    kg

  The specific heat of mercury wag1;e w7 b/+h vr(ijlzh 6x-hara(h1is $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,r+d7e wl dl.ot $250\,m/s$ 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 moving at:yklz uo n)3tr+d,,;vl, kion $6.4\,m/s$ 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 forenjycdw18,yu8a a6yvd +sic investigator notes that the 8.2-g lead bullet that was stopped in a doorframe apparently meltydcyayv8d8,u 6wa1+ j ed 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-lovvt90s+/qbv 8xlahqwl 4u (a.ng aluminum 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 condz1ev9;t slfz: uction in Example 14–10, assuming that there are:vz;19 tl sezf strong gusty winds and the external temperature is -5$^{\circ} C$   $ \times10^{4 }$ W

  (a) How much power is radiated by a tungste./gprsd.io8cc9e kv5sul 6 z+n 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 flow ,p2 l-xw,s 18qea;oqfgpdom y2g07h js by conduction from the blood capillaries ,o;xha2esd qgjpwp0 8 1qmg y2f -l,7obeneath 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 cu jl4dab0f o4f2be 4.0 m per side, share a 12-cm-thick brick wall. Because of a number of 100-W lightbulbs in one ro4 jlffd04ba 2oom, the air is at 30$^{\circ} C$, while in the other room it is at 10$^{\circ}C $. How many of the 100-W bulbs are needed to maintain the temperature difference across the wall?    bulbs

  How long does it take the Sun to melt a block hk 3klt61uz56nzym * dof 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 alumjx2eemm vt nyq/9:a(t3s:)kc ta xr1 )inum rod of the same length and cross-sectional area are attached end to end (Fig. 14–18). The coppm:exqt/ntesj):y9acm ( 1a vxt)r2k 3er 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 athiq:x *9:dnhw ks7x 1ubfp;k2 which the whole Earth receives energy from7ihds :*x ;q:2wu fkkb9nhp 1x 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 heatakdi i lvma 919 4stp+zipiu-ut-w7) 6, which is dissipated through a glass bulb that has a radius of 3.0 cm and is 1.0 mm thick.p- muiu17aw+4sdv9i6a z 9ik pitl)-t 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 house come mainly fr.y/ zzeww t/k1om 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 through such a wall, if its total areay1k w.ezw /z/t is $240ft^2$ and the temperature difference across it is 12 $F^{\circ} $?    Btu/h

A double-glazed window has two panes of glass sep-l1/-y rf vh vcco65j(ecoys9arated by an air space, Fig. 14–20. (a) Show that the rate of heat flow through such a window boecy frc1yv6vohj-9- /csl (5y 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 qvh 0oq4i;8;y0 megowxm y7r5s *lxd3ice 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 ayrm7xv+,-vp i bout 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 mw5he )ddnn* v3:jau6world’s oceans, estimate the heat luwd mvn):h dja*56n3e iberated 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.)    $ \times10^{ 15}\,J$

  A 15-g lead bullet is tested by firing it into a fixs-m/*/j g) ro8oleam bed block of wood with a mass of 1.05 kg. The block and imbedded bullet together absorb all the heat generated.m8se- r*/ gajb o)lmo/ 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 8-zj6gv3j l:trzr trhc9ij3(radiated into space by the Sun, assuming it to be a perfect emitter atrh i96 zrrtjzl-3jg8t 3 (cvj: $T\,=\,5500K$ 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 67n ikqy.:bdr-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 boulder rolls off the top of a cliff and falls a vertical hev3r5;f;bair5 aj cj7 vight of 1i3afv; a5 r7;jr5vb jc40 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 into a 2.5-L insulated pail oc bl+6bndo ./af water initially at 20.0+.ladb/nob6 c $^{\circ} C$. 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 thickgdbc151xn 4xm db7myzee7 92yq d;n8 n with total surface area;b xb1yd d15 7dg72nemyzm84qen 9xcn $1.2\,m^2$ 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 rsxga* fb0ulp8wy5yt 4 ;vv40 yeo;) yhate 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 intedaw;pdh+ v- -jrior of the body to the surface. Assume that the thickness of tissue is 4.0 c ph--+;dvwdaj m, 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 (assume conductivity of air4g ;w5 ew4ucyqb i9u4enni1 c5*l bwn() and arebcw(ie y*uwn 41lu;bw 5 cn594 gq4enia $410\,m^2$ 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 travew jq-hmuh79 z4ling 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 accounw* gij;uy xbll,2os*3 t radiation from the leaf to calculate how much water must be tran ;ywl*, 3bsgj2 il*ouxspired (evaporated) by the leaf per hour to maintain a temperature of 35$^{\circ} C$.    g/h

  An iron meteorite melts 1d 9ish8qz zk dau8 ,:ajwa6c.when it enters the Earth’s atmosphere. If its initial temperaturezau :d 8h j8k.,izawd9 c1sq6a was -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 u g5ka ;rc.p,(;ni on5srnqyz,a 6rh2the 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 people hit a soft rubber ball at areqmw8 az0g.*mji.3awn7af 9 wall until they are about to drop due to dehydration and exhaustion. Assume t7aw*waaf0mnme z8i.q3g j .r9hat 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 lucuf. (q0x32cit (f xequal 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 by co0xt5a00fd4fj *t tsndbr3 +irnduction and radiation at a raift d000ta xj*5rf 3n dts4rb+te of about 200 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” g*r8eb*v6d 7rs z7iv dleft in the 50-gal (185-L) w*b e8drd7r v*7gi6vszater heater. 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 aw;pj89bot 3g71* )uo oihoml z 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.    $^{\circ} C$