What happens to the work done when a jar of orange juice is v3 c8acxm7fq+:ffzsxf;8g7g figorously shaken?

When a hot object warms a cooler object, does) g9dv1rz qd mhe2/,sk temperature flow between them? Are the temperature cha,gd/m9krz )hevqds21nges of the two objects equal?

(a) If two objects of different temperatures arayub1i9m i q+f+8zx c8e placed 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 bqiz89f+u+yix m18c a are the same? Explain.

In warm regions where tropical plants grow but /t66za pwhct(bnf--x the temperature may drop below freezing a few times in the winter, the destruction of(tx/f66z a -t-w npbhc sensitive plants due to freezing can be reduced by watering them in the evening. Explain.

The specific heat of water is quite large. Explain whybw,+j-f .uoj ubm qb6(k+w x+w this fact makes water particularly good for heatibb.ww-q+ u k(f jb+w+o6m xuj,ng systems (that is, hot-water radiators).

Why does water in a metal canteen stay cooler if thz;hc+1:1jdmk) 0xxyuxs8z dp2f t, xye cloth jacket surrounding the canteen:0m18s ux x ,xj)cy2z;1f+yh dtzd pxk is kept moist?

Explain why burns caused by steam on the skin cht k0: (yussuws35g:p5swngj 2pn )(are often more severe than burns caused by waterh3snjg(:5 uu y)05( pkpctsgwsn2s :w at 100 $^{\circ} C$ .

Explain why water cools (its temperature drops) when it evaporates, usin/k7 fges*,q p9hk3 qjbn )x2hmg the concepts of latent heat an/qnhm7fj g 3q,bxkh29s*ep) kd internal energy.

Will potatoes cook fasterr8k yuz2w/ zcdh-a n075o;d,hd x s4bj if the water is boiling faster?

Does an ordinary electric fan cool the air? Why or why not? If nyd5.xtnx2p. *eol0w-pis s9v ot, why use it?

Very high in the Earth’s atmosphere, the temperature can be 701zk r w8/nbym20 $^{\circ} C$ . Yet an animal there would freeze to death rather than roast. Explain.

Explorers on failed Arc(vao h7qsy7z 0tic expeditions have survived by covering themselves withhya0q7s(v7 z o snow. Why would they do that?

Why is wet sand at the beach cooler to walk on than dryl4faj;d 5/r 5n sa9spl sand?

If you hear that an object has “high heat content,” does that mean thaz7 idf.82yase wn(8m:i;nvm yt its temperature is hifieyvw.a8nm(7 mnsz8 ;d iy2 :gh? Explain.

When hot-air furnaces are used to heat a house, why is it important that t/wl* xr /tx 0s.h hjho)np0)xohere be a vent for air to return to the furnace? What happens if this vent is bls h0t hoxjx*pnxh)/ w)r.lo0/ocked by a bookcase?

Ceiling fans are some5r lfm8r jd87 z8h(qgna a(7ha3vjih6times reversible, so that they drive the air down in one season and pull it up in anoth377a5 8drfv(ai6r mhq88hnzg(j l ajh er season. Which way should you set the fan for summer? For winter?

Down sleeping bags and paro8rnbgsyhk8ps0+38 sfo a6 7ry8ke 0ukas are often specified as so many inches or centimeters of loft, the actual thickness of the garment when it is fluffed up. Exp erykabs68o03 kns0uh fy78g+r8pos8 lain.

Microprocessor chips have a “heat sink” glued on top that lzaev o ,fg.8e ls+ase-);q*wd wnu5;gooks like a series of fins. Why is it shaped o algu f;a d*,wq.w ve+)z8e-5;ssg enlike that?

Sea breezes are often encountered on sunny days at the* a)z )+iml,xwu,a8 hxd88 rcx nton7e shore of a large body of water. Explain in light of the fact thoa,hw+zumx8at,r *x8ednln7x i 8 ) c)at the temperature of the land rises more rapidly than that of the nearby water.

The floor of a house onn-7gfspe 8o ( j(xb0ho a foundation under which the air can flow is often cooler than a floor that rests directly on the n -fb(o0o s(ejhp x7g8ground (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 i)acpe2ve0m 5nj -/jjd zm5s*(bz:dhg-w ,va thermometer in thpc5/egj5wbs ne,mzav a( j )djv zd-20*ih-:me shade.

A premature baby in an incubator can skkb( m m v,a;.b8ld-3q8lgvl be dangerously cooled even when the air temperature in the incubablvm.q-bvk;,al8g8 (m3d kls tor is warm. Explain.

Why is the liner of d6q-e6kl 9y;vtnjl t..iz ku8a thermos bottle silvered (Fig. 14–15), and why does it have a vacuum between ituj 8k6y-ld.i t.9vklte;6 qnzs two walls?

Imagine you have a wall that is very well insulated — it has a very high thfe9ge;vn:hwvhvu 1msq)39 oz3gnvpl 24 d+.e ermal re s1n)g.pv3 e9nvzo;q+v vfm 923u4:dhh wgleesistance, $R_1$ 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 process *neop2goipd:vr9; ) h(o8bvpes: (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, convection, or radiation? (b:);2r9id ohe gnov (p*bpvp8o ) Heavy curtains reduce which of these heat losses? Explain in detail.

A piece of wood lying in the Sun absorbs more heat than ap9 v3 zjpv3j 7f)r ,kdkq)pix4 piece of shiny metal. Yet the wood feels less hot than the metal,j )v3pj 4f7k)xvdrz9pik pq3 when you pick it up. Explain.

The Earth cools off at night much moregj+ 3qdqm2yq8yvia1 , quickly when the weather is clear than when cloudym gy,8i 3vq2qdq1jy+a . Why?

An “emergency blanket” is afte1* *e. 7mhtx2 an *gwqw5bm thin shiny (metal coated) plastic foil. Explain how it can help to keep ab*e2xt. *gqhw*e1m ta7wnmf5n immobile person warm.

Explain why cities situated by the ocean tend to l4 40z7i chq)a/shozphave less extreme temperatures than inland cities at the same lq4)l 4 z0h7c phoiza/satitude.

  How much heat (in joules) is required to raise the temperature of 30.0 kg of wawrl0sm ( +rrr-ter w(rr-ml0r + rsfrom 15 $^{\circ} C$ to 95 $^{\circ} C$ ?    $ \times10^{7 }\,J$

  To what temperature will 7700 J of heat 5bxyf x812fyfxctiw ej x-3ni (c666q raise 3.0 kg of water that is initially at 10.0i8 6 ift6b-x x63xj(fwy ye xcc1n25fq $^{\circ} C$ ?    $^{\circ} C$

  An average active person consrxta9mn/nj,/ ;w/ lstumes 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 i ,v2p) sgyain1n the British system of units. One Btu is defined as the heaty2gv)spin a 1, needed to raise 1 lb of water by 1 F $^{\circ} $ . Show that
1Btu = 0.252kcal=1055J

  A water heater can gt 2ty2 jv(09(ipsln e -pkn(u)4qf1nrg9 v nqsenerate $32,000\,kJ/h$ 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. E1x qmwr jau1k:0wd9 c61o0cf istimate how long it will take to he 1rjx1cwo auqcif96w100dk:mat 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 used to bre w v*zvwoy(u1-ar. *qing a 1200-kg car to resz. ue* vyaro( q-1vw*wt from a speed of $95\,km/h$ ?    kcal

  An automobile cooling sy b/by2,y)n fpqe6va6v stem holds 16 L of water. How much heat does it absorb if its temperatb ,fbya2y/v 6)vp6qen ure rises from 20$^{\circ}C $ to 90$^{\circ} C$?    $ \times10^{ 6}\,J$

  What is the specific heat of a metal substancehr zou 3ibw.*tw,k0xu8i6 ww 3 if 135 kJ of heat is needed to raise 5.1 kg of3*. ux6 r8owk0,zbihw3 ww tui the metal from 18.0$^{\circ}C $ to 31.5$^{\circ} C$ ?    $J/kg\cdot\,C^{\circ} $

  Samples of copper, aluminum, arf.p/ (m q;xdgnd water experience the same temperature rise when they absorb the same amount of heat. What is the ratipmr /qxd(. ;fgo of their masses? [Hint: See Table 14–1.]$m_{Cu}$ : $m_{Al}$ : $m_{H_2O}$ =    :    :   

  A 35-g glass thermometer reads 21u rhlxb2m2jm3* 4si7c(6jhls.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;b/p6fu aa zx+(la u6j temperature when a 245-g block of copper at 285$^{\circ}C $ is placed in a 145-g aluminum calorimeter cup containing 825 g of water at 12.0$^{\circ} C$ ? $T_{eq}$ =    $^{\circ} C$

  A hot iron horseshoe (masrmnm4v +3r r7zluzkf55 *(c dqs = $0.4\,kg$) 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 subs-x fnxibc3+ c4 jvt 2akwis.,/tance 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 9oqp-6ba1za - hmivws5 6xb*ga 750-W coffeepot to bring to a boil 0.75 L of water initially at 8.0p w- qh oagbab-1zv5im669*xs$^{\circ}C$? 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-v :7j4bl9h zhq: oxlga )ntk ,fap*z1 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 the mnl9k l p :ozftq*haz4h b)x:j-1, a7gvixture is 15.0$^{\circ}C $ , and its temperature after ignition is 53.5$^{\circ} C$ .    Cal

  When a 290-g piece of iron at pze.(2f ,;gu icfr2 3wrvhc2u180$^{\circ} C$ 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 hu8zmjx, falr +5 5dao9ammer 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 amount of heat nee u-fjmced /zjp.2n9y*ded to raise i9 ndy-pjjuce 2 *mz./fts 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 initialjud owvpj (c- a6n0+ -v.i b.vsw2(jlzly at 20$^{\circ} C$?    $ \times10^{6 }\,J$

  A 0.095-kg aluminium sphere is dropped from the roof of a 45-m-high building. -h,(lvi 0rnb sb qo+hs)vlq5+If 65% of the thermal energy produced when it hits the ground is absorbed by the sphere, what is its tem(5ib ,qvoq rsl) hl-sv+0+ nhbperature increase?    $C^{\circ}$

  During exercise, a person may give off 18; /,lwht.bn-vtteys- 0 kcal of heat in 30 min by evaporation of water from the skin. How much wat-wtb ,tls v;.-etnyh/ er 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 insulated cok)jq u8p6*0 l*hrhmvjbz*d h/ntainer of liquid nitrogen. How much nitrogen evaporates if it is at itqk0/8rdu )l 6* bj*jhpvzhmh*s 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 the freezer at -8b; ,bsu6e6s ggyi .rg1.5 $^{\circ} C$ 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 c p7b;cibsh/v .ontains 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 consuth9 / vyd9ddezh3 hzo96g2lmo (e k+ow:f4c)bmes 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 abocdl:ofbh39 ye2 +hg v9ztzo4d(/emh6dkw)9 out 20%, most of the energy consumed does go to heat, so our approximation is not far off.)    kcal

  What mass of steam atr5 3 5vycu1cr3yaw no1 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 mercury iiq be2mtp*c:3s $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/qf 2mjw w(b3:c s.quo 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 e3r1a* rj rt2/ xl1m+ xvvir2bat $6.4\,m/s$ 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 invesus0hx1c vdos-- 5.r(ti reh +btigator notes that the 8.2-g lead bullet that was stopped in a doorframe apparently melted completely on impact. A+trd( i5e- hs0bo s-.c xhr1vussuming 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 diam( a. +cvkn+jxr.cg2wq( o ni3seter 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 conduction in Example 14–10, assuming that thuvqaa)ut6b * ta*ib1sxw:rc : a 6i;5kere are strong gusty winds and the external tr*ka uxvit u5aw6 s6cq:a1it* );bba:emperature is -5$^{\circ} C$   $ \times10^{4 }$ W

  (a) How much power i :*vwvwj-*grp s 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 conductionu0l 3p/sn,nc b from the blood capillaries beneath the spc ul0n,n3/b 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 s)a s*ski ock;4z70xmbide, share a 12-cm-thick brick wall. Because of a number of 100-W lightb) *ki4c7km0bso x;as zulbs in one 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 the Sun to melt a block of iceto c;.7n osmk094phjol7 fyg4 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 7 ;yha6tofv6 xt(,u,impw3t z same length and cross-sectional area are attached end to end (Fig. 14–18). The copper end is placed in a furnace maintained at a constant tempe,m3(fp twy xo,uihvt6z;t7 a 6rature 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 at which the whole Earth receix q9,rl0aqedxbd.dgu 8x 9c*4ves energy xx e*9q4gu,9 qcb.addl 0d8r xfrom 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 dis9wdwwbd/xz *rp n80:msipated 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 an9d d/ :mx*wzwnwp8r0bd outer surfaces of the glass?   $^{\circ}C $

  Suppose the insulating qualities of the wall of a house come mainly from a 4.ehhd p,.et0m e,vc ;g+ bblc)*0-inp,;.de hg*c tm+, hl)b ebc0ve. layer of brick and an R-19 layer of insulation, as shown in Fig. 14–19. What is the total rate of heat loss through such a wall, if its total 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 ai*p66w zqzp*xt r space, Fig. 14–20. (a) Show that the ratez6*x6*pz tpwq 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 lohtj9( 5sjp f7cf e* .nutoomf;v2 57pgng should 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 c;51;(na3kz cth e5qh cwo rh(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 energyu,;p swzk:/;ijsl 6wy is contained in the world’s oceans, estimate the heat li;w,zi:;sywl js6k /u pberated when a cube of ocean water, 1 km on each side, is cooled by 1 K. (Approximate the ocean water as pure water for this estimate.)    $ \times10^{ 15}\,J$

  A 15-g lead bullet is tested by firing it into a f9ygc8fx.n- c (ssmvh(ixed block of wood with a mass of 1.05 kg. The block and imbedded bullet together absorb all the heat generated. After thermal equilibrium has been reached, the system has a tempera xnh8m yvc(s(9f.s g-cture rise measured as 0.020 $C^{\circ} $. Estimate the entering speed of the bullet.    m/s

  (a) Find the total power radiated lz oo+ bf;(akumt77vjx)23cb into space by the Sun, assuming it to be a perfect emitmz 3;7btaojl2xb co(u)f 7kv +ter 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 k*fn4x 3 ltbk4generate $200kcal/h$ 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 tov:w9 1ng st2ga2ib(h9pzc n3i p 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 genen9pg1c2 2v (zh93i:agist wn brated remains in the rock.    $C^{\circ} $

  A 2.3-kg lead ball is drsbr4mvzh c a9 v/.hk3s6r:u(o opped into a 2.5-L insulated pail of water initially at 20.hohasr:6vubc.(/4 z vks9r3m0$^{\circ} C$. 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 witqp y7kr+/ja;: yosdi9h total surface area ;iyqkj sd /9 7p+o:yra$1.2\,m^2$ 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 rtwh hfjbnhp0cbmd3 340;r alb2m/6v)ate 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 fromn1 jlwfmq+/v; the interior of the body to the surface. Assume that the thickness of tissue is 4.0 / vl1qf jnmw;+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) and w)1vj5p si:+x gwzmh yq9yu4.z (pmss z,o8z(areazi jhos v +uq8,s95y:yx pmwzmg.(p1sz(4)zw $410\,m^2$ 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 a;(+g-msf3nn+.izbaj w23y d swfw- vy6 smg*bt $220\,m/s$ 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 vyzej*m 3 p+h6radiation from the leaf to calc *hvp em+j3y6zulate 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 atmosphere. If its h *d20ahf ycbxbev5); initial temperature was ye2 vh50hx; ab*c)dbf -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 abo8lyw qka 1xvu+ 6sccke g.w*+,po7zo: ut 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 h4f i4wl,cep, bit a soft rubber ball at a wall until they are about to drop due to dehydration and exhaustion. Assume t4b ifp4,,lew chat 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 ma ,14. y -fpcxj oo6xr6hwtw0kksses 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 conduct(v+-t8 oszkz 7sh)rw o0anf8gion and radiation at a rate of about 200 W. Estimate how long it wof)ok o r-gz0(+7a 8z8svthnwsuld 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-gal scu* 7q;lr,xrmw79sv(185-L) water heater. This suggests that the tank has emptied and refilled with water at,v;*r9lc swsqrmu7 7 x 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-W li30qi ez pt(u7jghtbulb 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.    $^{\circ} C$