What happens to the work done when a jar of oran zmk9(vgr qttgx7 9j9*qul3x-l 1uby) ge juice is vigorously shaken?

When a hot object warms a cooler object, does temperature flow bewr7ff;d 71x+1y ws ypktween them? Are the temperature changes of the two obje1f ;1ww dk7+xysyfp 7rcts equal?

(a) If two objects of different temperatures are placed in contact, will heat bx6 +( qmg-)qipox3vnnaturally flow from the object with higher internal energy to the object with lower internal energy? (b) Is it possible for heat to flow even if the interg+ixnqx-) vp m6q(bo3 nal energies of the two objects are the same? Explain.

In warm regions where tropical plantsmo /n2m. lqftg.0.y kx grow but the temperature may drop below freezing olgfq t20mx/.m kn.y .a 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 water is qnfb ro f ppw*aa u3+n,z)1ht,0uite large. Explain why this fact makes water particularly good1*th,ppwnz ua 3f),banf0o r + for heating systems (that is, hot-water radiators).

Why does water in a metal canteen to1*pdlov99 fstay cooler if the cloth jacket surrounding the canteen is kept flp v1o9 td9*omoist?

Explain why burns caused by steam on thnzh 5tv9ku/ig 0z ; -p0i)guj0ybo/rse skin are often more severe than burns caused by wat/z/;orh gy5vui90ij0tn -uzp b gks0)er at 100 $^{\circ} C$ .

Explain why water cools (its temperature drops) whc/r.z64(wbekg 3 4myba p rs3len it evaporates, using the concept3c /3a6b (4 k4rgm pl.rybzswes of latent heat and internal energy.

Will potatoes cook faster if the water is boilinaa/ zprfu h :-g 1;acz4dki/a8g faster?

Does an ordinary electriczeg*b3 zk20jf fan cool the air? Why or why not? If not, why use it?

Very high in the Earth’s atmosphere, the temperatuyajc06q7wbh 45 f 8tnkir 6xk;8lz( rure can be 700 $^{\circ} C$ . Yet an animal there would freeze to death rather than roast. Explain.

Explorers on failed nc(n/pt3d9m sn /zed;a6u s0wArctic expeditions have survived by covering themselves with snow. Why would theyumcnnde/t6 9s;pw 3dnsz( / 0a do that?

Why is wet sand at the beach coomqm5*lgx:xn7 ler to walk on than dry sand?

If you hear that an object has “high ud *zff,ov:o6 * i+migheat content,” does that mean that its temperatureuidz gofofm6 +iv*,:* is high? Explain.

When hot-air furnaces are up;ze:u*8 wbyvf;fgd72e-kdw sed to heat a house, why is it important that there be a vent for air to return to the furnace? What happens if this vent is blocked ukzw;f:f yded;*b - wp27vge 8by a bookcase?

Ceiling fans are sometimes r stbs idz.( dc8b7y5v-eversible, so that they drive the air down in one seass.(vdcz d 7-5tbb yis8on and pull it up in another season. Which way should you set the fan for summer? For winter?

Down sleeping bags and mey f +ezb;+o9parkas are often specified as so many inches or centimeters o+zy;o +ebm9ef f loft, the actual thickness of the garment when it is fluffed up. Explain.

Microprocessor chips have a “heat sink” glued on top that look1wepv9z8 v q,js like a series of fins. Why is it shapej e 9w8,1pqzvvd like that?

Sea breezes are often encountered on sunny days at the 9zt9uw5 rp 0y6 bhkg:oshore of a large body of water. Explain in light of the fact that the temperature of the land rises more rapidly than that of thg zh6ut990r:y 5o wbkpe nearby water.

The floor of a house on a foundaoobv z8126wim:ft5 wx v./nv stion under which the air can flow is often cooler than a floor that rests directly on zvtmb5/ oxwv:svf16n .2ow8ithe 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 readings are always taken with the thermometer in z s .fq0rc a6x+)h lpesycvo .pf)..:qthe vfce6lss zy qqro+. p:.)hafpx)..c0shade.

A premature baby in an incubator can be dangerously cooled even when th,k0b2 6rplxz rw+qs1vd mg+1je air temperature in the incud21b 1+0x +jqk plr6rw ,mvgzsbator is warm. Explain.

Why is the liner of a thermos bottle silvere iy3w)i k3ow*id (Fig. 14–15), and why does it have a vacuum between its two w3i3yik)oiww *alls?

Imagine you have a wall that is very well insulated — kq)l83 o2.ki hgkh tv k;8pul,it has a very high thermal resi hp;k3uikl,kl 8k) 8.o2vgthqstance, $R_1$ 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: (1gbop o jdyl3yac)tx5.9l.l9h6 .* v jo) ventilation around edges; (2) through the frame, particularly if it is metal; (3) through the glass panes; and (4) radiation. (a) For the first three, what is (are) the mechanism(s): conduction, convection, or radiation? (b) Heavy 9tylo j)p 9.vjgh6d b.53xao.lcl*oycurtains reduce which of these heat losses? Explain in detail.

A piece of wood lying in the Sun absorbs 0 leo lmv-/f(pmore heat than a piece of shiny metal. Yet the wood feels less hot than the metal whenpvml/(-f e0lo you pick it up. Explain.

The Earth cools off at night much more quickly when the weather istdcg); we2),nmiicg) clear than when cloudy., 2t)mci) gw)ge icdn; Why?

An “emergency blanket” is a thin shiny (metal coated) plastic foil. Explafvi3 w cj4;8jf(q4de he;ur eu5oo3 g/in how it can help to keep r5o;3fqi(c4 g uf4eju 3ed/e8 ;jhovwan immobile person warm.

Explain why cities situated by the ocebk1mtie ( * 230*lkqvmu *ktdjan tend to have less extreme temperatures than inland citie1k02*tqkmljikvd e*(3 m* tb us at the same latitude.

  How much heat (in joules) is required to raise the4lvhps4 xi0* +( hdep yk7w7yn temperature of 30.0 kg of water frysl iknye+v7w4p04h7x(hdp* om 15 $^{\circ} C$ to 95 $^{\circ} C$ ?    $ \times10^{7 }\,J$

  To what temperature will 7700 J of hed m yy r6iebu4(: l(g+yin-(hcftk 23aat raise 3.0 kg of water that is initially at 10.0 (i(( myf3l+- : tygahricydb2e4 nku6$^{\circ} C$ ?    $^{\circ} C$

  An average active person consumes about 250mi lz. glv9i)*0 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 (f:78b8 thc6vyfj ik8l g0 gu(rBtu) is a unit of heat in the British system of units. One Btu is defined as the heat neede8g 80b7ify8cu(h kv6:tjgrlfd to raise 1 lb of water by 1 F $^{\circ} $ . Show that
1Btu = 0.252kcal=1055J

  A water heater can gener;8c5qxwd0,ide5bls+blz*a h3c s ai-ate $32,000\,kJ/h$ How much water can it heat from 15 $^{\circ} C$ to 50 $^{\circ} C$ per hour?    kg/h

  A small immersion heater ispuixff 20;o/r rated at 350 W. Estimate how long it will take to he ipf;rf2uo /0xat 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 brakes are useclujw (w 1s .+wrdbq94d to bring a 1200-kg car tobdqr .wu wc 1sw4+9j(l rest from a speed of $95\,km/h$ ?    kcal

  An automobile coolingv (m) j-7 / thrnogh:dgl7q(ek system holds 16 L of water. How much heat does it absorb if its vd(g) (7e-krh lq m:jot7/g hntemperature 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 hbwe,dre/) n 1reat is needed to ra1wdern)/ b ,erise 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 temperature v6txh+xxazo (u r9:snw3h,5erise when they absorb the sa nhueh rvxxzo+a(65sx 9 :w3t,me 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 reaxx : 2yup,v6dqvuufu*.wz4e lnb2f4 7ds 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*9js2;)o.azi x gktdj 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 (ms1v-ez8kdp /sass = $0.4\,kg$) 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 vwcgd/c p be 9taxe3g 531y67lzr-s)asubstance 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 a boil 0.jua.e f03+,1 mvm zh)s(q prjju)yt wf.-cwk175 L of water initially at+f s) e ptu,.jr(q1fmhvkjzuy3 c0w).wma- 1j 8.0$^{\circ}C$? Assume that the part of the pot which is heated with the water is made of 360 g of aluminum, and that no water boils away. $\approx$    min (Round to the nearest integer)

  Estimate the Calorie content of 75 g of candy from u f.qo 2kq7tf/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 aluu/ ktfq27o f.qminum 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 v9ej y7.-ex n(z rh s5wc2n1oairon at 180$^{\circ} C$ is placed in a 95-g aluminum calorimeter cup containing 250 g of glycerin at 10$^{\circ} C$ , the final temperature is observed to be 38$^{\circ}C $ . Estimate the specific heat of glycerin.    $J/kg \cdot C^{\circ} $

  The 1.20-kg head of a hammer has a sfzdnn r6+* 6a:i6dndp peed 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 needed tox)0 x:efz7dce raise its temped :7xf zxec0e)rature 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 dv1t3flf 0ij mi 8taj/*6cg- gygt:a; silver that is initially at 20$^{\circ} C$?    $ \times10^{6 }\,J$

  A 0.095-kg aluminium sphere is6xgc ewh:ilwku 8mrru n8*3b f46 c).n dropped from the roof of a 45-m-high building. If 65% of the thermal energy produced when it hits the ground is absorbed by the sphere, what is its temperature f3c6 i8ulrhwg n xnc8.wu4rb: km)e6*increase?    $C^{\circ}$

  During exercise, a persob8a sjj,3r8z4h;zqdw3 k * ml ,3dryznn may give off 180 kcal of heat in 30 min by evaporation of water from the skin. 3 ,kmsz 8zdn;qyawb,ldj r*3jr8 4z3hHow 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 dropped into an in x /7+0qdl6m/uric mxr*dtok ,sulated container of liquid nitrogen. How much nitrogen evaporates if it is at its boiling point of 77 K and has a latent heat ofq0cmkl d7ux i,rm+t*d /6/xro 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 frn, (n d*lhp9 ire(uos 5:dwa3aom 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 cont3qnh:+i gw -qtzwd j,:ains 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 bicyclist consumes 8.0 L of water over the span of four hgqi7vvcozx / gp.(07 aoi2 s-h:k az7vours. 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 consum2/xvqp cz:h gv7iok 7g-vsazio . (70aed does go to heat, so our approximation is not far off.)    kcal

  What mass of steam at 10)9v c qd;mofh80$^{\circ} C$ 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 rlfpua0ae* j+ rh3 )vyht0:j.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 at8:xz346q mda2k tdptl $250\,m/s$ 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 moviq1 n0r:k( w9ce :g4j42jtlq0ojkxf1*biu jivng 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 th 2r(9b)7o1ifekc ir uqe 8.2-g lead bullet that was stopped in a doorframe apparently melted completely on im e9cr)(71or2f iq ukibpact. 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-+;xlg h6jwcl. qd:n p 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 con,ucp5e lt 5lpm2a+7jr-ql0f sti5du 4 duction in Example 14–10, assuming that there are strong gusty winds and the external temperatur5+ tprle7c2p ui5adj0,u l5f t4q- lmse is -5$^{\circ} C$   $ \times10^{4 }$ W

  (a) How much power is 9ao7 pjocwdq8g 5rb7g(ew75de 6l0lh radiated by a tungsten sphere (emissivity $e\,=\,0.35$) of radius 22 cm at a temperature of 25$^{\circ} C$ ?    W
(b) If the sphere is enclosed in a room whose walls are kept at -5$^{\circ} C$ what is the net flow rate of energy out of the sphere?    W

  Heat conduction to skin. Suppose 200 W of heat flows by conduction from m315w, *fw 5:l wprzo zydv )h uoa0f4)vdq/ifthe blood capillaries zmi)) ,f 3l/pfy51fdhwoza4 vd5qw0v :wuo*rbeneath 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, shb u*dy ltnnmh.52.*snnu rl/pp4o mu 9-zir:+are a 12-cm-thick brick wall. Because of a number of 100-W lightbulbs in one room, the a tn2m *.5nhp um/ :l94rluou-b*sd n nyzri.+pir 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.nj: 3 m/czp9a(lfs d k1mwjq, block of ice at 0$^{\circ} C$ with a flat horizontal area $1.0\,m^2$ and thickness 1.0 cm? Assume that the Sun’s rays make an angle of 30$^{\circ} $ with the vertical and that the emissivity of ice is 0.050.    h

  A copper rod and an aluminum rod of the same length and cross-sectionaldh0yz(a d k+l7(ky2kv area are attached kal+vhk0yz7d( 2 ykd(end to end (Fig. 14–18). The copper end is placed in a furnace maintained at a constant temperature of 250$^{\circ} C$. The aluminum end is placed in an ice bath held at constant temperature of 0.0$^{\circ} C$ . Calculate the temperature at the point where the two rods are joined.    $^{\circ} C$

  (a) Using the solar constant, es*.h5fv e p, bc)8jkpodtimate the rate at which the whole Earth receives energy fh.oejcp8bk v ,*pd)5from 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, which is dissipated throustzmm vbg v 42vt7+6c kbem,qz3 ta2y.((f+j agh 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 and outer surfaces of4tb ,s t2m3ckyav2z mz.vm6ftb7gv( a(+ ej+ q the glass?   $^{\circ}C $

  Suppose the insulating qualitie52f . 9asco+.hya bwui) 6y/.ggstu ros 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 wall, if its totu2 )gy/ yoast.osu fcghr9 i 6.a+.b5wal 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 spacu5 (;xx7 c7 wav c9tdi62nyosje, Fig. 14–20. (a) Show that the rate of heat 7oacx wy sud597v(c2 jx ;tni6flow 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 shoutkobaz ro g-5ew9 6 .w7m-tjjhk9bd/2ld 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 about 0.20 kg of liquid kamz0kv0 pek0 tm: y 9tvq 2)w4:wd7qhat 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-eaur,wf8a: :/bd xgz1o yrc. is contained in the world’s oceans, estimate the heat liberated when a cube of ocean water, 1 km 8dxr/o, w:uyf.za e1crga :b-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 fixed block of wo.hx;6 k3k p rth65cdtuod with a mass of 1.05 kg. The block and imbedded bullet together absorb all the heat genert5kdhhxr.3 tp6c ;k6uated. 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, assumin9. guqfd) j;04whj bnzh +is*fg it to be a perfj.)sh* ;b inj0f4 gqw+ hfzu9dect 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 i e;/m- vjfuct4z1i7lyff l7+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 svitc1c(h 7e ur4 zco8p3 m0e oo+g07hoff the top of 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 heat generatedt00ecg7u8 orp4 hmc iez +hc3v(os1o7 remains in the rock.    $C^{\circ} $

  A 2.3-kg lead ball is dropped into a 2.5-L insulated pail of*b* ck( szhbh9 water initially at 20. c*bhskz9b(* h0$^{\circ} C$. 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 jacn e,knqsa/9 t(ket 3.5 cm thick with total surface area nq, t(ns9ka e/$1.2\,m^2$ 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 metab hgmoju 6m*n2rn:,)vzbsxs 28olism 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 nvvk) mgfua i4f02 ):othe interior of the body to the surface. Assume that the thickness of tissue is 4.0 cm, that the skin is ato)f k fmiu04:nvv2ga) 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 conductivit nr b4avzta/dmx/ 6t4ruw2 i):y of air) and area x2w6 4t/a)tua 4i/brv nrdzm:$410\,m^2$ 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 travei:u1a;rxq6 wmix* (9hg( abqbyl7( ho ling 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, tv+*m2 ued l3otc,8sz +wid6juake into account radiation from the leaf to calculate how much water must be transpired (evap3wj udmc tz idvsu82 +ol,+6e*orated) 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 atmosphere. If irgw*pj hb9)3 blrf+1w ts initial temp w3+hj9pgb1lr w*fb)r erature 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 i3o*sr d fe4ad-ncreases 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 a*nzrc8tqde ( 1;cksy3t a wall unt z8en (yrks31*ccqt;dil 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 wx66 jkh 6zr9( 3yobs:8sdxjvmasses 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 conductioz(wg,4v+/b wat ufq ex++ lk-yn and radiation at a rate of aboukwb, e/g xv+zfw+ul+( t -4ayqt 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” lefv iazn/n/mgj4z1/z,4 i svi 3wt in the 50-gal (185-L) water heater. This suggests that the tank has emptied and refilled w/szaiw3z 41vim/n n g j4vz/i,ith 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 tde2s .kyww 8b3he 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.    $^{\circ} C$