What happens to the work done when a jar of orange juice is vigorously shanm .8(vcfusqyzn r)35gr g+ e,ken?

When a hot object warms a coolu/qpq*u 9dve4g 3z)*x5m geh mer object, does temperature flow between them? Are the temperaturu ve u9m/geg)3pdzmq*h 4q5*xe changes of the two objects equal?

(a) If two objects of different temperatures are st xwpd 0 g3:hq4b):ieplaced in contact, will heat naturally flow from the object with higher i4 b0i3q we: txhgd:s)pnternal 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 the temu ph.s3/ef drk6, w)tnperature may drop below freezing a few times in the winter, the destructio/pft6. rwnk edhs,)u3 n of sensitive plants due to freezing can be reduced by watering them in the evening. Explain.

The specific heat of water is quite large. Explain why this fact mct206xhjfns4 f2k m,g jz)kt1akes water particularly good for hx,mktcft s )2nk2g61 4jfjz0heating systems (that is, hot-water radiators).

Why does water in a metal canteen 2bnnnau,mgfcsu()h 0) 7 m6i34iixrjstay cooler if the cloth jacket surrounding th, )0()r3chbmi2nxign us64 jamin7 fue canteen is kept moist?

Explain why burns caused by steam on the skin are often morevjzu9 j30 6mdx severe than burns cauj3 mj0ud6v 9xzsed by water at 100 $^{\circ} C$ .

Explain why water cools (its temperature drops) utgfq3y6ei5zql /z 1bm9b 4k0 when it evaporates, using the conke5mb0 y/ q4g3 t16uzb9zlqif cepts of latent heat and internal energy.

Will potatoes cook fbrh3 mf y/b 23hv 3vq6mbh56nyaster if the water is boiling faster?

Does an ordinary electric fan cool the airsx c21dxy 10 7 z.0aylfyj;(axqs3a th? Why or why not? If not, why use it?

Very high in the Earth6;o.uit o;sdr ’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 have14bukwpt bk usu14tl(.+h/ tr survived by covering themselves with snow. Whyut s1.p/( lrk u4bw1+4htbkut would they do that?

Why is wet sand at the bew(2zfll8 0izv*n,jgxqyxy7qo t s +39 ach cooler to walk on than dry sand?

If you hear that an object has “high heat qr9 /vj:fg4wb content,” does that mean that its temperature is high? Explaqr bj vw/9f:g4in.

When hot-air furnaces are used to heat a house, why z fe-wg4uru 9j/ 4lfzio5dh pmv0;r9 *is it important that there be a vent for airu flgp-; 9jrzd i/hv o9*0 uewrz4m4f5 to return to the furnace? What happens if this vent is blocked by a bookcase?

Ceiling fans are sometimes reversible, so that m: ezri66(o ppw6cu 4kthey drive the air down in one season and pull it up in another season. Which way should you set the fan for summer? For winp:o z6e ku ri64wc6p(mter?

Down sleeping bags and pa (7t,eqw cpj7irkas are often specified as so many inches or centimeters of loft, the actua7c(w ietjp7q,l thickness of the garment when it is fluffed up. Explain.

Microprocessor chips have a “heat sink” glued on top that looks likew1pw1awi byxzs g39 94oi,nekmx.a7; a series of fins.o3 axbs ,n9m.kpi7z1w x;w9yeg4 iaw1 Why is it shaped like that?

Sea breezes are often encountered on sunny px,zphr, ;:x sdays 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 tx,z: rps ;p,hxhe nearby water.

The floor of a house on al;+)hu q701 fxoosknk foundation under which the air can flow is often cooler than a floor that r1o0knlx +ko7;h)fsquests directly on the ground (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/)(2fj7), rib kr plbrwmkbgdpk 0 7d: readings are always taken with the thermometer in the shade/k:gw( d7kpkr2lp)7 j)r rb,md0fbib .

A premature baby in an incubator can be dangerouslyzq:3gt-mfp/1uwa8d s cooled even when the air temperature in the int:wd mp1 8qz 3-fugsa/cubator is warm. Explain.

Why is the liner of a thermos bottle silvered (Fig. 147vzsk6pkw:g 1 –15), and why does it have a vacuum betwk 61pgvwzks7 :een its two walls?

Imagine you have a wall that is very well insulated — it has a j3q(qold;)d 7q+phw7.ebcr rda h ve-2mn8o: very high thermal resi7;mp3l2d)j+c ndhdq7rq(a-:reeq o boh8. w vstance, $R_1$ 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:ja05 31wmbw5xh hjth( (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(m(0jhhx3w w 51a 5jhtbs): 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 more heat than a piece of shiny metal. 4udlrhr0k(f /Yet the wood feels less l0 k(hfurr4/ dhot than the metal when you pick it up. Explain.

The Earth cools off at night much more quickly when tn6t hyuh/tk we x:xqo60(1 vgly6(3mshe weather is clear than when cloudy.x(tlshmyyqg6kevu :3 xo(016 tnh /6w Why?

An “emergency blanket” is a thin shiny (metal coated) plastic foil. Explmnn1- ;mzbd n 55sx yk onda(we61n8*gain how it can help to keep an immobil 6zn8daym* 5(kdmw51 1e-; bsxg nnnnoe person warm.

Explain why cities situated by the ocean tend to have less ex xu t8t6.nh0tztreme temperatures than inland citie6h0 tzu t8t.nxs at the same latitude.

  How much heat (in joules) is required to raise the temperature of 30.0lfv-w 8cx-+lc 6r dlj; kg of water from 15 +-;l-c lf ljw6dx8rvc $^{\circ} C$ to 95 $^{\circ} C$ ?    $ \times10^{7 }\,J$

  To what temperature will 7700 J of heat raise 3.0 kg of water that hja ,b qqrd)ceihm5uz*azuu e6,3998is initially at hedzq) *8q9uj 5r3h ,bcze 9aa6u,imu10.0 $^{\circ} C$ ?    $^{\circ} C$

  An average active person consumes abe 5bv hm-q bo1o xs6h/x:.n(ibout 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 B:iy s1p+t ycr7l)m(zn ritish system of units. One Btu is defined as the heat needep:s(+m tcnyy) 1zi7r ld to raise 1 lb of water by 1 F $^{\circ} $ . Show that
1Btu = 0.252kcal=1055J

  A water heater can generctvs cc; -0r 19 4txq1qff+slbate $32,000\,kJ/h$ 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 vebeo* :er8;2(y s 6hbb.yd)ya0j us zhe. y(ae6e8dus2:0ryhy o;z) *bsevj bb at a cup 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 bra z,icrp; me.fjc (d-df ;qg49nkes are used to bring a 1200-kg car to rd qn(z9 mcdpf;eficj- ,.rg4;est from a speed of $95\,km/h$ ?    kcal

  An automobile cooling system holds 16 L of water. How much heat does it k1chd05s3 ht 9k r hn*zqe1pw;absorb if its temperature rises from 2 c*h n95wpq h10rhse3 zdk;1kt0$^{\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 t -ndmawwb2emm k(li9)m9t,w .8 o8qpao raise 5.1 k8m e)kwwwq pm9.-db8 mla9n 2imt(ao ,g 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 te l hq2emr5nxs;4(nnu,mperature rise when they absorb the same amount of heat. What is the ratio of their masses? [Hienm5n 4,2l hrsnq;(xunt: See Table 14–1.]$m_{Cu}$ : $m_{Al}$ : $m_{H_2O}$ =    :    :   

  A 35-g glass thermometer readsk owvj74glhp bus9, hf3)6ox) 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 wh/ts )sa p.q;ebgt *k1lliw;3 qen 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 .g6ub-p9se 9hq pnq hy0s-m r:(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 33 p ;acgcvt3e u ,fd9zrdqi;)6b)er ;w)0$^{\circ} C$ 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-Wu-v wk 2rpmd 4 j).8xcwn*zt+h coffeepot to bring to a boil 0.75 L of water initially at) r.ukvw2m+zd 8chjnt* w- px4 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 c)hjesnu 7,bfxv-f/5ft e6ds (ontent of 75 g of candy from the following 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 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 th (tuex 5,v/fe 76h f)dn-jsbsfe mixture is 15.0$^{\circ}C $ , and its temperature after ignition is 53.5$^{\circ} C$ .    Cal

  When a 290-g piece of irr5yizbwhgx f0,.++w rbj87 a mon 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 htk .h ce08zl43 mesob2na1 3da 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 ,szx xe4ugw8,w1 o1hu amount of heat needed to raise iewwx48hs1o ,ug,u x1 zts 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 silvxpsqolr ,4og,608 :g1pkd neb er that is initially at 20$^{\circ} C$?    $ \times10^{6 }\,J$

  A 0.095-kg aluminium sphere is dmzp2,d egtl 3)ropped from the roof of a 45-m-high building. If 65% of thg2 zlt)mpe,3 de thermal energy produced when it hits the ground is absorbed by the sphere, what is its temperature increase?    $C^{\circ}$

  During exercise, a person mahe 6s;q ai)8ory give off 180 kcal of heat in 30 min by evaporation s;)6eoq i8 hraof water from the skin. How much water has been lost?    kg

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

  A 30-g ice cube at its melting point is dropphcon;4(bnp.vutu2 e+ ed into an insulated container of liquid nitrogen. How much nitrogen evaporates if it.;un 2b4te(ov u+p nch 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 d * s,u) 6b.a*ikp11enraq(nipzuq k, from 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 d(3 ei-ms0jn:usv*e f18$^{\circ} C$. 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 water ove0 jmaay2xt -7v* s h.8wfosn4kr 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 abou 4 s.a728 wfk nxyo-vsam0*hjtt 20%, most of the energy consumed does go to heat, so our approximation is not far off.)    kcal

  What mass of steam ax(g99wd b8w cqt 100$^{\circ} C$ must be added to 1.00 kg of ice at 0$^{\circ} C$ to yield liquid water at 20$^{\circ} C$ ?    kg

  The specific heat of mercs1lghrx8dvy( kr+9x o m2ko(u+e1i5r ury 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 travelb/wlwu(g*ytv1oz:t 7 ing 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-skater m*h -ekqa3o(qz j s:g*doving 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 lj(8s4;g6zkd l vfx2- x,4dkau zl4pgnotes that the 8.2-g lead bullet that was stopped in a doorframe apparently melted compl6a;kdlx2dl gj4kup4z8fgsz x( ,- 4vletely 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 ,9 i **v7)xngnuhz tgncm 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* 55mru at806ygy( 8xsgxetg vt flow by conduction in Example 14–10, assuming that there are strong gusty winds and thettyg5se0u xy8m58*r (6gvxag external temperature is -5$^{\circ} C$   $ \times10^{4 }$ W

  (a) How much power is radiated by a tungsten sphere (c itu6/i0t fj-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 hemgavzll4n26(r) dqr 0at flows by conduction from the blood capillaries beneath the skin to the body’s4206l zald rmqrn)v (g 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-cwsfe1urz1 giqdn s0) * :otf/4m-thick brick wall. Because of a number of 100-W lightbulbs in one room, the air is 0/s*erq 1wtgs1zi) :fou fn4dat 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*l jkap,dtyr,bb6 5* e 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 le*:*g cf zq:p 6xfy ie59v*qmqgngth and cross-sectional area are attached end to end (Fig. 14–18). The copper end is placed in a furnace maintained at a constant t*cp:zef q9 vif6yx *qgmgq *5:emperature 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 c; f-edsgs7yag+8lm-3g my :fm onstant, estimate the rate at which the whole Earth receives e;sg:gy7da em+ ysmm--f g fl38nergy from 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 heat,lva)ykafj7 4i-y*e1 m which is dissipated through a glass bulb that has a radius of 3.0 cm and is 1.0 mm thick. What is thea1 v4e -my)7lajy *kfi difference in temperature between the inner and outer surfaces of the glass?   $^{\circ}C $

  Suppose the insulating-ry t4 /f(q+*4j wrvtzxpcs i.pvz z:- qualities of 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 total rate of heat loss through such a:xvtr-rv y*4.f/q + zjpt4iz-s(pcz w 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 se0l(m/c(p 9xogg wn +czparated by an air space, Fig. 14( pc/(nc g0+mlgz 9wxo–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 long should it take 11.uhi )69euln )zu-nz0s0 kg of ice at 0$^{\circ}C $ to melt when it is placed in a carefully sealed Styrofoam ice chest of dimensions $25\,cm\times\,35\,cm\times\,55\,cm$ whose walls are 1.5 cm thick? Assume that the conductivity of Styrofoam is double that of air and that the outside temperature is 32$^{\circ} C$.    $ \times10^{4 }$s

  A soft-drink can contains about 0hygbx5 8uuz1 don gnc8jd97:b m08) fd.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 much3v2bw(tv 2 rts thermal 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 1t(bwrvs vt232 K. (Approximate the ocean water as pure water for this estimate.)    $ \times10^{ 15}\,J$

  A 15-g lead bullet is tested by firing it intoq2pdb n 2cb,c) a fixed block of wood with a mass of 1.05 kg. The block and imbedded bull2qc dp)c2b,bnet together absorb 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 S gqv;y.wdc .a4w5 ix2run, assuming it to be a perfc.; qgda5wiy 2x4 rv.wect emitter 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 may g-ui js: ufc/nixlw ,4)3u( cbtenerate $200kcal/h$ 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 of7:uykm.iysi.rp 7wa 7 a cliff and falls a vertical height of 140 m before striking the ground. Estimate the temperature rise of the rock if 50% of the p w:7 7m.i.kriya7suyheat generated remains in the rock.    $C^{\circ} $

  A 2.3-kg lead ball is de i:c;i5yd5bj9;gqcv *y0o viropped into a 2.5-L insulated pail of water initially at 20jy0 bcgi*c qvv: yi5d5o9;ei;.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 sja5:)xago +( khb5exgoose down jacket 3.5 cm thick with total surface area a+)5sgh5( ojx:axb ek $1.2\,m^2$ 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 avpii gz*fm ltxmx)33j.sg9- s 7erage 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 the inyx663 il:e,dwgg/ eq dterior of the body to the surface. Assume that the thickness of ti,xqi6 geledg6 yw3d:/ ssue 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 (assume co+vk1 qoo(a va3n.2ywc nductivity of air) and nq . a 1ok23v+cvyw(oaarea $410\,m^2$ 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 tlol- t z8tp-e:raveling 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 mie-:w a8d1xcaccount radiation from the leaf to calculate how much watee 8x1wdaim -:cr 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 enp t: dyz) 3wl4bz.c2wbters the Earth’s atmosphere. If its initial temperaturctwb:l.zy 2p b3)wd4ze 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 Earth’s crust incret v)+rf(ms a)eases 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 pw ,fi1*j j /pf2netqh9eople hit a soft rubber ball at a itp21jj q,n*w /f9fehwall until they are about to drop due to dehydration 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 at4gd o2k5hb ;wd 0$^{\circ} C$ and steam at 100$^{\circ}C $ are mixed together?

  In a cold environment, a2+)kieuwdgzt*i *on ,9g9cjt person can lose heat by conduction and radiation at a rate of about 200 W. Estimate how long it wouldtik dgjc9unt g)w2**, i9zoe + 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” left in the 50-8p,, /lm qkmv5sx)eobgal ( ols, m/8v)qk,em b5xp185-L) water 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 a 60-Wib2nl9i36:ef 5ejibxl, yi/s tb)1gr 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.    $^{\circ} C$