What happens to the work done when a jar of orange juice is vp l;m s(d+5xpp res, x/4;vkqwigorously shaken?

When a hot object warms a cooler object, does te69 h wvf*hjrp/mperature flow between them? Are the temperature changes of the two objects eqhw6j rf/9*hpv ual?

(a) If two objects of different temperatures are plaezx,c/ 7g-t /nsuujxc-yr8jtw7*8 j yced in contact, will heat naturally 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 internal energies of the two objects are the same? Expljc g8xrye u8/c yxz s7j-u -tt,n/*7jwain.

In warm regions where tropical plants grow but the tem.g ks7r1 .e9k gk3do p/mev6fcperature may drop below freefkkgg cmve.e / 9.s7k63od1r pzing 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 fkct7zz71 bo. (kot0a-vq / eoquite large. Explain why this fact makes water particularly got bfka07cto(z ze.okqv- /71ood for heating systems (that is, hot-water radiators).

Why does water in a metal canteen stay cooler if the cloth jacket suru ds m t qsx4u)3b/ob9i5yf*ee0dw d01rounding the canteen io mdi 0 sx*3des0bu49/qw)5u b1f dytes kept moist?

Explain why burns caused by steam on the skin ar2 38ui:b 2tv xhcawil3e often more severe than burns causelcw383ii:ab u22xht vd by water at 100 $^{\circ} C$ .

Explain why water cools (its temperature drops) when it evaporathju 6(c set:0ssr4z;nes, using the concepts of latent heat and innuh ;: rj6stzsc0se(4 ternal energy.

Will potatoes cook faster if the water is boio(93c ka)4xseog c n(nling faster?

Does an ordinary electric fan cool the air? Why or why not? If not, why us .1ho:l,kfyd/nplx 5 vts/ hu7e it?

Very high in the Earth’s atmosphere, the temperature can bejp5ikp+)k q: -jk8s c :b*kbax 700 $^{\circ} C$ . Yet an animal there would freeze to death rather than roast. Explain.

Explorers on failed Arctic expeditions have survived by covering thems 4x ;c 6ed5aoipt3s.jshek(4yelves with snow. Why wouldck 5s y.(ej6xt4oi4 epa3hs;d they do that?

Why is wet sand at the beach coox7zv8r z *mfl)ui.4 dwler to walk on than dry sand?

If you hear that an object i(: xu azc6am94n -crwhas “high heat content,” does that mean that its temperature ic-xnmcz 9ur4a(a w:i6s high? Explain.

When hot-air furnaces are used to heat a house, why is it important that therx3hu bfw:41.p+a3o*cj +x : pmdsccvm e be a vent for air to return to the furnace? What happens if this vent is blocked by d uobf*vw 3m3 :a:1sh.c+jc c pxm4px+a bookcase?

Ceiling fans are sometimes reversible, so that they drive the air down in on m5tm b-h0(wy 1h6 iq-;y,vd*glaou gne season and pull it up in another season. Which way should you set the fan for summer? For winter y *a vmh, ibgu6 ;y-(d0mlt51woqn-hg?

Down sleeping bags and parkas are often specif;ne6 zi lzky;or0*q1jm+coc3ip: u, oied as so many inches or centimeters of loft, the actual thickness of the garment when it is uq3poyc;+o,mjikz o ;c e:ri 1l z*60nfluffed up. Explain.

Microprocessor chips have a “heat sink” glued on top that tw h0jvxk 1 u;vms52*llooks like a series of fins. Why isv0h x1 w*5um;v2ktsjl it shaped like that?

Sea breezes are often encountered on sunnyq w*0o,rf cb)k days at the shore of a large body of water. Explain in lighf co rbk,)*qw0t of the fact that the temperature of the land rises more rapidly than that of the nearby water.

The floor of a house on a foundation under which the air can flow is ofbgm1o 51v7k *ipj:a glten cooler than a floor that rests direct7 5ai1pjgbl 1go*vk :mly 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 readings are always taken g04 og3(i, okvm1l*n/n/hj( bck zvtlwith the thermometer in the shadoozlv0 bn cgg1vt3j*k(n kh4,i/ (m/le.

A premature baby in an ige*x1ubj 8.vd hfcji 19 ::fzwv76 ufnncubator can be dangerously cooled even when the air temperature in thfe7dwun gf bzi .v1jcf9 u6h: j1*vx:8e incubator is warm. Explain.

Why is the liner of a thermos bottle silvered (Fig. 14–1aq284 a eez-w ah)zk1e5), and why does it have a vacuum betw ka)a8eewz 4 2h-zaq1eeen its two walls?

Imagine you have a wall that is very well insulated — it has a veryzf duq5fi6ps)2 u + r.u5kdg-h high thermal resistance,d ruhu) 5gsp-z. 5qkd2ff+ui6 $R_1$ 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 wind m gh5dw5p+(dws,r 7coows by the following processes: (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(s): conduction, convectiog hdmw+o(5 d7pr wc,s5n, 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 thana ix/0 ,gv1gaz a piece of shiny metal. Yet the wood feels less hot az0i,v /g xga1than the metal when you pick it up. Explain.

The Earth cools off at night much more quiye1)d(n4 --r+fdzv4 ezt dbb bckly when the weather is clear than when clo-4r)nezzd bf b v+(dbe -d1t4yudy. Why?

An “emergency blanket” is a thin shiny (metal coated) plastic foil. Explain j fj:xkvds;/ qh6:9nj how it can help to keep an imh:jk x9v /fd6jjsq:n; mobile person warm.

Explain why cities situated by the ocean tend to have less extreme temperatures t*j8--p:8g-bsmvvq ng1xym nthan inland cities at thp gnq -mn1 xjm s:*-g-btv8v8ye same latitude.

  How much heat (in joules) is required to raise the temperature of 3ik5uh6; tai 89dtxd s60.0 kg of water from 96d;5t has ut6x8ikid 15 $^{\circ} C$ to 95 $^{\circ} C$ ?    $ \times10^{7 }\,J$

  To what temperature will 73+ ;p-riihjlie cct8 mt ,j )nzm:0c;g700 J of heat raise 3.0 kg of water that is initially p0 3 me; c;jilz,cm:r-ig n)hitc+ j8tat 10.0 $^{\circ} C$ ?    $^{\circ} C$

  An average active person 5igs:xaq s)9: qildf, consumes about 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 British syst,4 q7r)j v0b+wsbjo2sibrq .oem of units. One Btu is defined as th+ ijbs0ws4qqb 72oor vj.b)r, e heat needed to raise 1 lb of water by 1 F $^{\circ} $ . Show that
1Btu = 0.252kcal=1055J

  A water heater can generate6:isbd.dh7p 3 qfpw5ijw 79jm $32,000\,kJ/h$ How much water can it heat from 15 $^{\circ} C$ to 50 $^{\circ} C$ per hour?    kg/h

  A small immersion heater is r6 b (hz6q-az wfe)vz-oated at 350 W. Estimate how long it will take to heat a cup of soup (assume this is 256) (zo-6wqaeh-zvzbf 0 mL of water) from 20$^{\circ} C$ to 60$^{\circ} C$ .    min

  How many kilocalories are generated when the brakes are used to bring a 1200-6ft d)b(s 9nujkg car to rest from a s bfdtjs9n )u(6peed of $95\,km/h$ ?    kcal

  An automobile cooling system holds 16 L owd zdv3n v5(/,ko, sstf water. How much heat does it absorb if its t5z, s (/3vs, ktwondvdemperature 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 neede(:t: 44 dxqzrrpz zmq6d to raise 5.1 kg of the metal fr:(rpzrm44q x6d tq:zz om 18.0$^{\circ}C $ to 31.5$^{\circ} C$ ?    $J/kg\cdot\,C^{\circ} $

  Samples of copper, aluminum, and water experience the same temperature r/rh sb gn k0pc y*-6oaje4k*e-ise when they absorb the same amount of heat. What is the ratio of their6gb kco h- e*jpenky/ *s0-ar4 masses? [Hint: See Table 14–1.]$m_{Cu}$ : $m_{Al}$ : $m_{H_2O}$ =    :    :   

  A 35-g glass thermometer reads 2xeyy4* xl8s6fy7 qsu/ 1.6$^{\circ} C$ before it is placed in 135 mL of water. When the water and thermometer come to equilibrium, the thermometer reads 39.2$^{\circ} C$ . What was the original temperature of the water?$T_{iH_2O}$ =    $^{\circ}C $

  What will be the equilibrium temperature when a 245-g block of copper at 28zg 1ptr .:kz1u,bmfw;t7.y1q df2o sk5$^{\circ}C $ is placed in a 145-g aluminum calorimeter cup containing 825 g of water at 12.0$^{\circ} C$ ? $T_{eq}$ =    $^{\circ} C$

  A hot iron horseshoe (mass w uz : qs)cy/e2i2h3m r5bcqv8= $0.4\,kg$) 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 akqm,osq b a14.6b3vvheated 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 tscoje ,.8eq) so a boil 0.75 L of water initially at 8osqj .c es,)8e.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 o n-szwfv:8 n+;ll8n3 4m ulgrif2os8g of candy from the following measurements. A 15-g sample of t-l;no8glf2u sz8f+3: irwv8ol4n msn he 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 the mixture is 15.0$^{\circ}C $ , and its temperature after ignition is 53.5$^{\circ} C$ .    Cal

  When a 290-g piece of i v vbvy.7d.pd;ron 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 h-m qw3rnb* rxbmrc4):as 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 amount of heat needed to ram-bm0cz u h/1yise its tempbhc1- ym /uz0merature 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 initiallyk5ibw a;fi4:h8o zq y3;+ijmm/5 zu su at 20$^{\circ} C$?    $ \times10^{6 }\,J$

  A 0.095-kg aluminium sphere is dropped from the roof of a 45-m-high building. Ifbgw(zx6j1 m/jv5 ec-i 65% of the thermal energy produced when it hits the ground is absorbed by the spv( /zw ibx5gcjm e-16jhere, what is its temperature increase?    $C^{\circ}$

  During exercise, a person may give off 180 kcal of heat in 30 min by evaporat.vucey ,4 k*m4o;sae )vfnwd(ion of water from the skin.kycse),vefud4m (4 ow v*; .na 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 droppedv +k):lr, f2nzr5 p zq5ydho4b into an insulated container of liquid nitrogen. How much nitrogen evaporates if it is at its boiling point of 77 K and ha 4,d5)2r5pn f:z hvqlbrzyo+ks 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:fj(k( led5ix/eo lkbc+ bq-+ 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 1y; / zy:sddo2esxf /pt2hj c,.8$^{\circ} C$. 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 c j:ih s,0ej;pa2itr6s onsumes 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 sj06isespj2 ; hrtia ,:weat, how much energy in kcal did the rider use during the ride? (Since the efficiency of the rider is only about 20%, most of the energy consumed does go to heat, so our approximation is not far off.)    kcal

  What mass of steam at 100l7+u b(obeee+-r)w eo $^{\circ} C$ 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 igi4)o*t) mfc;nli7xk s $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 travelinit4e n3x1, u,l6j/ ufs7 cyjdtg 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 moving atpe qx8tx2o 3)/awweb5h 8k3vu $6.4\,m/s$ 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 t w 8 ifb5-jb9mv0o:qvrin vs00hat the 8.2-g lead bullet that was stopped in a doorframe apparently melted completely on impact.fvv09- n5iw bvm0bjq osr :i08 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 diameter3o ;d10g)d emv 6. 6h;fyul el4ob kps4tcitq( 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 conducti68 t2yj1r tfx xyb ixn;j-n8 z*skp/4pon in Example 14–10, assuming that there are strong gusty winds p*jnxt;b fi1z 8tx4nr x2yps6-y/8 jkand the external temperature is -5$^{\circ} C$   $ \times10^{4 }$ W

  (a) How much power is radiated by a tungsten sphf-6g7d + 2abmlyz qn7bx9i1tuere (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 blov95c/l(yw 2z yab g8wrc1n: *(xj6bsxi rfdg2od capillaries beneath the skigyga yi(j5bx 2 w2drv/* 1scz6f bnwrc8:( x9ln 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, share f +bs4 fp:d6dma 12-cm-thick brick wall. Because of a number of 100-W lightbulbs in one room, the air f+pd6dfm4b s: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 b7 axe4g v gef 1;-x6hgnqdt5p6lock of ice at 0$^{\circ} C$ with a flat horizontal area $1.0\,m^2$ and thickness 1.0 cm? Assume that the Sun’s rays make an angle of 30$^{\circ} $ with the vertical and that the emissivity of ice is 0.050.    h

  A copper rod and an aluminum rod of the same length and cross-sectional y:il+lbsho dmun) )dlh 649q5 area are attached eq )m:h bl9s4hd+u )nyo65dllind 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, estimate the rate ab/j.sszd4uvp fuw 6:f mvu310t which the whole Earth receives u/m pf 4 z 0ssvv63b:f.jud1uwenergy 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 t+mwu8q- 7xnfof 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 inutfmqx8+7w n- temperature between the inner and outer surfaces of the glass?   $^{\circ}C $

  Suppose the insulating qualities of the wall of(yt1ln8 gp4y6 1xzbhm i uko6; 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. Whuimy t4( ;z1xhyk ln866bg1p oat 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 pa4k l66at-u /q ce /qruj:5q+auqua yz5nes of glass separated by an air space, Fig. 14–20. (a) Show that the rate of heat flow throkjluuucz +ar aa e/56q:5-u4/yq 6tqqugh 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 takx7:-cw2 a 6llp.9rb2glmpjtx e 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 td7vv2g 2q6 7*(rdmo;gc oa htof 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 nvo);m s mv11v.hvym 2zeb00xthe world’s oceans, estimate the heat liberated when a b o2v yxz0. mv) 1env0mvh1;smcube 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 fixed block of wood wit bf4f9z.m mx3zh a mass of 1.05 kg. The block and imbedded bullet t3fm 9f 4.xzzbmogether 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 radutiwc /n+.hcf 7qgi9q) ,kb.3ylfu4eiated into space by the Sun, assuming it to be a perfect i w9yqiu h7qu+nf. b 3kf,c.gc/te)l4emitter 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 activitcr*gnfvyxj:b7 .w o20 r) tox(y, a 70-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 0.z(ieutqsfsr0hs lz,9 ep (v-ue 3(mthe 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 generated q0 ilf((h(smvuzpe ,u9t3e0e. ssr-zremains in the rock.    $C^{\circ} $

  A 2.3-kg lead ball is droppaw 6cq dzhts8t g*v 4(m/v;pu7-zf z5sed into a 2.5-L insulated pail of water initially at 20ts5hv d z6g;ut7q 8*4ws-(czz/v mp fa.0$^{\circ} C$. If the final temperature of the water–lead combination is 28.0$^{\circ} C$, what was the initial temperature of the lead ball?    $^{\circ}C $

  A mountain climber wears a goose down jacket 3.5 cm thick with total surfak3;plkxof .we6z7 :nlce arewk6e: p; xn3z.l lfo7ka $1.2\,m^2$ 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 aver:p*cirtf e8qwg mk)1)age 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 interior of the bodysfv;hir 5;*d4h w2 yty to the surface. Assume that the th2wdv;fy5* 4 h ;tsyirhickness of tissue is 4.0 cm, that the skin is at 34$^{\circ}C $ and the interior at 37$^{\circ}C $, and that the surface area is $1.5\,m^2$ Compare this to the measured value of about 230 W that must be dissipated by a person working lightly. This clearly shows the necessity of convective cooling by the blood.    W

  A house has well-insulated walls 17.5 cm t9gfko6pd(: gihick (assume conductivity of air) and arfg6o(g :9kpdiea $410\,m^2$ a roof of wood 6.5 cm thick and area $280\,m^2$ and uncovered windows 0.65 cm thick and total area $33\,m^2$
(a) Assuming that heat is lost only by conduction, calculate the rate at which heat must be supplied to this house to maintain its inside temperature at 23$^{\circ}C $ if the outside temperature is -10$^{\circ} C$    $ \times10^{5 }$W
(b) If the house is initially at 10$^{\circ} C$, estimate how much heat must be supplied to raise the temperature to 23$^{\circ} C$ within 30 min. Assume that only the air needs to be heated and that its volume is $750\,m^3$    $ \times10^{ 8}$J
(c) If natural gas costs 0.080 dollars per kilogram and its heat of combustion is $ 5.4\times10^{7 }\,J/kg$ how much is the monthly cost to maintain the house as in part (a) for 24 h each day, assuming 90% of the heat produced is used to heat the house? Take the specific heat of air to be $0.24\,kcal/kg$$\cdot\,C$.    dollars

  A 15-g lead bullet traveling at 7gpacz6mkk ay m*2(akjbqvt/8i )j/0 $220\,m/s$ 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 acckim,;y w q1hrd6t/j 8. dcs6 ax4(stqhount radiation from the leaf to cald8thxkqtc64;,qda(s6 rhmw .jys / 1 iculate how much water 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 a d 5ccj8vl 98t 6z(ce6mnx4mystmosphere. If its initial temperat ml5v cs48(x96yemctj 8 nz6dcure 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 increases about ykjjmzfb :1k7 :hk6b7 oarp3 ;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 of9dfqr) 9:f yvr squash (Fig. 14–22), two people hit a soft rubber ball at a wall until they )9d rf:f yq9vrare 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 ez5pmxp(jh)4jnn3 0cq qual masses of ice at 0$^{\circ} C$ and steam at 100$^{\circ}C $ are mixed together?

  In a cold environment, a person can lose/+d 9s abupxg8 heat by conduction and radiation at a rate of about 200 W. Estimate how long it would take for the body temperature to drop fu +9 xgdapsb8/rom 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 509 d r37e vmb8bcbt;fl9htz8+l-gal (185-L) water heater. This sugges;m9bcdbv7tl8zl+bhe 8 3rf 9tts 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 subxwk+b k)hv*6t:jmpc3-xt q :rface 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.    $^{\circ} C$