What happens to the work done when a jar of orange juice is vigorjnch 1pb42pv5 ously shaken?

When a hot object warms yxc i,u16f+ 84qvwutc3i3ra ba cooler object, does temperature flow between them? Are t6fv rw +b83c41qx,uti3a uycihe temperature changes of the two objects equal?

(a) If two objects of em n-qly:7e+ch5 kk2y different temperatures are placed in contact, will heat naturally flow from the object with higher internal energy to the object withnk eyl2:5yq7ehk +cm- 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 the temperature may drop s7 zs;m0 9twlibelow freezing 9 tzwl ssm;i70a few times in the winter, the destruction of sensitive plants due to freezing can be reduced by watering them in the evening. Explain.

The specific heat of wacq,/qi /;lu5 3r- 4 ndqgnsakyk l45bdter is quite large. Explain why this fact makes water particularly goon,/y4i-5d 5/qdkl;nqgl 3asqkcr4 b ud for heating systems (that is, hot-water radiators).

Why does water in a metal canteen stay cooler if the cloth jacket sq 1z*sd vkn+: k:ifh)w wvp27rurrounding the cav+fphw7 r zi2 vq:*kws )nk:d1nteen is kept moist?

Explain why burns caused by sta(0gcn4y-enqy;eg.y w ( 1zvceam on the skin are often more severe than burns causedw(e.ncgy aeyn10v z(yqgc;-4 by water at 100 $^{\circ} C$ .

Explain why water cools (its temperature drops) when it evaporates, uxian83 ;wk/v gi)aqc3sing the con/wkgx ;a q3vca3 )8niicepts of latent heat and internal energy.

Will potatoes cook faster if the wate5xiw -h(sc6 hur is boiling faster?

Does an ordinary electric fan cool th/gfwztj p8c 2:lzn+ t)e air? Why or why not? If not, why use it?

Very high in the Eartqgs-ghkhi8 ) 79,wry yh’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 expeditions have survived by covering* k:sn4 natqt0y, m+fg themselves with snow. 0n 4 tmtsqgaf*+,ny:kWhy would they do that?

Why is wet sand at the beach cooler to walk opo hh)b3 vbfwa+r3 7g9n than dry sand?

If you hear that an object has “higvisi12;g6)zw 2 ghbdcjy)2vez,y vo 5h heat content,” does that mean that its temperature is high? e1v ods)yyvzh2g 2v, i65jcgi;wz2b) Explain.

When hot-air furnaces are us.y.uc nks98 doktin5 .k3 bz*ced to heat a house, why is it important that there be a vent for air to ret.s ckn yik.bo5 u9tzk38c*nd.urn to the furnace? What happens if this vent is blocked by a bookcase?

Ceiling fans are sometiie*d;irn7l2cq(zp 0i9aie y(mes reversible, so that they drive the air down in one season and pull it up in anothei( y lipq* nier(9i7;a0 cdz2er season. Which way should you set the fan for summer? For winter?

Down sleeping bags and parkas are often specifiedpjh6/ a 1p2c/ tmdsl;f as so many inches or centimeters of loft, the actual thickness of the garment when it is fluffed 62t c/dmpaps 1jfl /;hup. Explain.

Microprocessor chips have a “heat sink” glued on top that ld1,p ,tza)m* u9ihhrrooks like a series of fins. Why is it shap)pau*i , ,rz1h9hrdt med like that?

Sea breezes are often encountered on sunny days at the sho(e/ymp5x dohm-(sc f6y bp s(1re of a large body of water. Explain in light of the fact that thxy fb/cde((p1o-m5h(sp s m6ye temperature of the land rises more rapidly than that of the nearby water.

The floor of a house on a foundation under ,2jkft) r gk- q-jqqk/which the air can flow is often cooler than a floor that rests directly on the ground (such as a concrete slab foundation).q gq2/f, q)t-j kjk-rk Explain.

A 22 $^{\circ} C$ day is warm, while a swimming pool at $22\; ^{\circ}C$ feels cool. Why?

Explain why air temperature readi8h k chhz cyr(;d3l+f8ngs are always taken with the thermometer in thhl8cy8d f; hz+h3(cr ke shade.

A premature baby in anbygi14xl 4m3 ff* +xiu incubator can be dangerously cooled even when the air temperature in thl f*i 4y14gxfu +x3ibme incubator is warm. Explain.

Why is the liner of a thermos bottle silvered 2r jwc8 ky/kbp: fyf5)(Fig. 14–15), and why does it have ab2k:8pcy f jfw/5yr)k vacuum between its two walls?

Imagine you have a wall that is very well insulated — it hl(s ottoegzguv9dpq1 ig4 k , 3q;(m*(as a very high thermal resistan(to*u9 ode3mpg(, ;klgt4z(1i vs gq qce, $R_1$ 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 ;;+i-k8nu*pfwgmxdu *4 f a dqwindows by the following processes: (1) ventilation around edges; (2) through the frame, particularly if it is metal; (3) through the glass panes; and (4) rnf*-8udqx;gkdum*wipa+; 4 fadiation. (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 lyinya9qr4 t6wnf e7-t4luo( nps 4vei (d6g in the Sun absorbs more heat than a piece of shiny metal. Yet the wood feels less hot than the metal when you pick v( wlpn 6r f4e 47tqyae96to4-( suidnit up. Explain.

The Earth cools off at night much more quickly when the weather is clear than wh *at5d6 r4k.sfuyy k;ylxigi8/+n t k8en c85k *;d yay .+it/x kigklfn48tr u6syloudy. Why?

An “emergency blanket” is a thin shiny (metal coated7jg1fq 5v5k jto4- niz) plastic foil. Explain how it can help to keep an immobile person wkqi5o-v5j7 z4gjfnt1 arm.

Explain why cities situated by the oce50osx,tl +y ttan tend to have less extreme temperatures than inland 5+txs,lto y0t cities at the same latitude.

  How much heat (in joules) is required to rajdj zb.i3.5b aise the temperature of 30.0 kg of water from 15b5.a3i dbzj.j $^{\circ} C$ to 95 $^{\circ} C$ ?    $ \times10^{7 }\,J$

  To what temperature will 7700 J-8bqs for1pt : of heat raise 3.0 kg of water that is initially at 10.8f 1 bo:pqs-rt0 $^{\circ} C$ ?    $^{\circ} C$

  An average active person consumes about 2500 Cal a day. hu .. hrz)pcxmxamb k1-3h6m q:m9yu*
(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 ut*lqb 4.qj9:+f 7we ,hfehdjmnit of heat in the British system of units. One Btu is defined as the heat neede jfd:*9h, +qqj. fmw ee4bt7hld to raise 1 lb of water by 1 F $^{\circ} $ . Show that
1Btu = 0.252kcal=1055J

  A water heater can genera5s qidw wd6ty3 5b/tx1te $32,000\,kJ/h$ How much water can it heat from 15 $^{\circ} C$ to 50 $^{\circ} C$ per hour?    kg/h

  A small immersion heater isl((n r9u-tvi q rated at 350 W. Estimate how long it will take to heat a cup of soup (asv-u( inrt9q( lsume this is 250 mL of water) from 20$^{\circ} C$ to 60$^{\circ} C$ .    min

  How many kilocalories are generated when 7ygp:qz i/p 0vthe brakes are used to bring a 1200-kg car to rest frogi p: zv70yp/qm a speed of $95\,km/h$ ?    kcal

  An automobile cooling system holds 16 L of water. How eq0e;vi(d zip ec61t,.fra l+much heat does it absorb if its temperature rises from 2qid.ti+evpc16 ;,rafe e( z0l0$^{\circ}C $ to 90$^{\circ} C$?    $ \times10^{ 6}\,J$

  What is the specific heat of a metal substance if 1r - d.o ;o3; j;pk1str6ylkwve35 kJ of heat is needed to raise .rp6-vkd;lotyjkoe;r 1w3s; 5.1 kg of the metal from 18.0$^{\circ}C $ to 31.5$^{\circ} C$ ?    $J/kg\cdot\,C^{\circ} $

  Samples of copper, aluminum, and water experience the same tempes mf.jrc1vzlb6f3 9 +r 2f-qelrature rise when they absorb the same amount of heat. What is the ratio of their ma639zb rr e+-2jqs mf.c1 lvfflsses? [Hint: See Table 14–1.]$m_{Cu}$ : $m_{Al}$ : $m_{H_2O}$ =    :    :   

  A 35-g glass thermometer readsz hzj7g/fehjmkw; 24dp 71/ nz 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 temp2ekc0ce jk 0f m57vmb)erature 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 horseshoe (ma:x f5 lvf+k.top*2cm /vhdtxs ki *f9-ss = $0.4\,kg$) 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 substail( kpe.y6/jqcd9 e4.r)wl z ance 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 takzkf ( ,)csegu3s)atr*e a 750-W coffeepot to bring to a boil 0.75 L of water initia)3 ,sf a)ts cr*(gekzully 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 co(2+.goa kwaq intent of 75 g of candy from the following measurements. A 15-g sample of the candy is allowed to dry o.i a+(gkw2q abefore 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 at 18y:7y7kq4ugqagsu:lz 80 h j+x0$^{\circ} C$ 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 ac gnq7ihy.y( 5qs 4(zn hammer has a speed of $6.5\,m/s$ just before it strikes a nail (Fig. 14–17) and is brought to rest. Estimate the temperature rise of a 14-g iron nail generated by 10 such hammer blows done in quick succession. Assume the nail absorbs all the energy.    $C^{\circ} $

  The heat capacity, C, of an object is defined as the amo kcr7 w(wugl)*unt of heat needed to raisk7c()wg* uw lre 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 i(cm6duuo:.xehc z/)znitially at 20$^{\circ} C$?    $ \times10^{6 }\,J$

  A 0.095-kg aluminium sphere is dropped ffr ,, mx3sj lkt3la9zmk a(,8grom the roof of a 45-m-high building. If 65% of the the xma39k3ft, l8,rg j sma,zl(krmal energy produced when it hits the ground is absorbed by the sphere, what is its temperature increase?    $C^{\circ}$

  During exercise, a person may givdc 74.ked 1kk u)bjf;de off 180 kcal of heat in 30 min by evaporation of water from the skin. How much waterdjd. 17ek 4d;u) cfkbk has been lost?    kg

  If $2.80 \times10^{ 5}J$ of energy is supplied to a flask of liquid oxygen at -183$^{\circ} C$ how much oxygen can evaporate?    kg

  A 30-g ice cube at its melting point is dropped into uc7b )epwnr9:)un .guan insulated container of liquid nitrogen. How 9u:nr n uu))ep b.w7gcmuch 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 the7ct6 /*x4t br xvso3hn 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 waterb;4j+rvk d ds; 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 co+ux3. s0l g+nuj/ vtvonsumes 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%x + us/0+vtovgl nj3u., most of the energy consumed does go to heat, so our approximation is not far off.)    kcal

  What mass of steam at z(d,7; ynt2buox(su c100$^{\circ} C$ 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 me l1q+n2 2n5udkumph+ mn(j5u0c j) vuxrcury 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 apc i0t3 ph -bpi;:th:vtgt 2s;t $250\,m/s$ 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 movinp.hbf4c dhk3h1/l 6n g wf82ang 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 /rrfu;o. )n9 pzjh+ hethe 8.2-g lead bullet that was stopped in a doorframe apparently melted comzufo+hr;/jp h9) nre .pletely on impact. Assuming the bullet was fired at room temperature (20$^{\circ} C$ ), what does the investigator calculate as the minimum muzzle velocity of the gun?    m/s

  One end of a 33-cm-long aluminum rod with a diameter of 2.0 6 7 s,ycbaj in8n+-weocm 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, vkqa.r c:d;t5z pm /7 d qqbzj-.f5a3massuming that there are strong gusty winds and the externa5p5fjmq qq;b- dta. 7av. /dmrz ck:3zl temperature is -5$^{\circ} C$   $ \times10^{4 }$ W

  (a) How much power is radiated by a tungst3ij0u6or 4rn ten 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 the ankvs;: *h* deblood capillaries*n;*dkve:ah s 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, sharmxfo26pe0 4e 2 f0trfte a 12-cm-thick brick wall. Because of a number of 100-W lightbulbs in onp0 6 20em xtteor2ff4fe room, the air is at 30$^{\circ} C$, while in the other room it is at 10$^{\circ}C $. How many of the 100-W bulbs are needed to maintain the temperature difference across the wall?    bulbs

  How long does it take theebum w n w.k4wj:m:24i 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 ro/bih zsalmml g+1 f;61d of the same length and cross-sectional area are attached end to end (Fig. 14–18). ; hfms+bl/6mia1z1gl 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 th 7qcbduc,k8u1 )ouo a0e rate at which the whole Earth receives energy from theo q d0,uokuc8)7u1abc 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 dm*f45y2/x o l ,gkoyr g4mpl 3*wf/qmof heat, which is dissipated through a glass bulb that has a radius of 3.0 cm and is 1.0 mm thick. What is the difference in temperature between the inner lk d2p,rq yl4 mx 5fy/*w4 fom3omg/*gand outer surfaces of the glass?   $^{\circ}C $

  Suppose the insulating qualities of the wall of a house come mainly from a 1 vd6;9 bnadpqbngk1p) 5w z )edkn5:c4.0-in. layer of brick and an R-19 layer of insulation, as shown in Fig. 14–19. What n ;zdvb5gp)6 a)ek5w kn91pd 1qd ncb: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 gl8hwm6z,t ku f6w0fayd/s8;f1phd2 p wass separated by an air space, Fig. 14–20. (a) Show that the rate of heat flow through such a window by condwh;dywhu z6 k8,a1p0/2f f6ft pm8s wduction 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 2-nua v6 osx4l*upmtz1 u52mhshould it take 11.0 kg of ice at 0$^{\circ}C $ to melt when it is placed in a carefully sealed Styrofoam ice chest of dimensions $25\,cm\times\,35\,cm\times\,55\,cm$ whose walls are 1.5 cm thick? Assume that the conductivity of Styrofoam is double that of air and that the outside temperature is 32$^{\circ} C$.    $ \times10^{4 }$s

  A soft-drink can contains acbj nkvg6 (dzbn,(qrt8cj(3 , 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 containeddj tuh256h.tc in the world’s oceans, estimate the heat liberated when a cube of ocean water, 1 km on each.tutch 5 dj62h 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 fixed block oiod0q(:x)+es2zchv + ;ksp x yf wood with a mass of 1.05 kg. The block and imbedded bullet together +;+dhko)xcy:pssz q e(x0i2vabsorb all the 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 space by the Sun, assuming it r *cbu3f g4qhl5m/n 6lto be a perfect emitu6 /b3*lc4rq gmhnf l5ter 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 pers y,s; nkz/fvx*on 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 tff g/wodl40kc *vhtws80 5mm-he top of a cliff and falls a vertical height ov8td m4gwfk-fm 0/ s5w*cl oh0f 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 into a 2.5-L insulated pail of water ini nawda97aic1/tially at 20.07i/a9wan1dc a$^{\circ} C$. 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 thiwy68;7:j;iy 5,,xh5u hl shhw6dcv iku n6fdjck with total surface arec yhuyiix7h u,;8jw5,6 fh nh: s 5jv66wdkl;da $1.2\,m^2$ 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 ra63so / xxz-,ek5afyil te 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 inumvw6 dd47ut: 2lwff +terior of the body to the surface. Assume that the thickness of tissue iw: l6t7ud uf 2wv+fm4ds 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 (assume conductivity of air) andihlspf+q,ic),+* jq d arip +,*hljfq,iq+)sd cea $410\,m^2$ 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 jjq +;zninag+mpco8 :b .a 4m17fd/sdv 6mj7 iat $220\,m/s$ 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 account radiation fdzq ,y3 wp7wy,rom the leaf to calculate how much waterypz3,, dwqyw 7 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 atmosphkr.gxo69v5 lm ere. If its initial tempe6gmlv .kx5r9 orature 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 the Ealao2+oj5-db( bmj:n3qw: cjrtvl1n - wq/v b6rth’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./rdn q2; ixx8+0s psun 14–22), two people hit a soft rubber ball at a wall until they are about to drop due to dehydration and/id2snnp u+0rxx s 8q; 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 aur8q+m+yd ;6 ,f eb xvgckj11ut 0$^{\circ} C$ and steam at 100$^{\circ}C $ are mixed together?

  In a cold environment, a person can lose heatlv5lff;3n4zckg/;6cxyrl+(i c,en o by conduction and radiation at a rate of about 200 W. Estima, cv;l l ln;4y f/x kizgeco(r5c+n3f6te 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 dis/mm ;byqj l.1phwashing, there is “no hot water” left in the 50-gal (185-L) water heater. This suggests that the ta/;.q 1jmy pmlbnk 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 thee(qzf t -rsw4 5elk/+p glass 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.    $^{\circ} C$