What happens to the work .n 3rbu:qwiy 7done when a jar of orange juice is vigorously shaken?

When a hot object warms a cooler object, does temperature flowkegps b4e 1dui1(:kdk eg52e-t9w-lw between them? Are the bdww4-g2u gted9ee i(k-k5:lks11 p e temperature changes of the two objects equal?

(a) If two objects of different t0xuru.rlm :*;r *o gjsemperatures are 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 are the same? Explai:m*jrgus.l*; r 0uro xn.

In warm regions where tropical plarhlcw + 6eej+ si:*/ponts grow but the temperature may drop below freezing a few times in the winter, the destruction of sensitive plants due to freezinjhs6w el /+ce*:rpio +g can be reduced by watering them in the evening. Explain.

The specific heat of water is quite large. Explain why this fact makes water qhq+* nd gmz8ds u3*9;+dhr /dwv foc/par *+cw+; nms3uzg oqd9dqh8 dfdvh/r*/ticularly good for heating systems (that is, hot-water radiators).

Why does water in a metal canteen stay cooler if the cloth jacket surroundingmi.(.+6fsfi8j 7a0ipxgr b:lrzh - ez the canteen ix8z (:.jisi6hr fer0af.+b g7z i-pl ms kept moist?

Explain why burns caused by steam on the skin are often more severe than bur4 2grmarl, 5ug(vuf-vns caused by water at 10v-gvr,f 4 gu ualm5(2r0 $^{\circ} C$ .

Explain why water cools (its temperature z+w7a.zgsfwk7 hpt1h ,.s+ wxdrops) when it evaporates, using the conceptsw+ 1hhf ks7st7xp w,za .zg.+w of latent heat and internal energy.

Will potatoes cook faster ,apa zk97bnb jblqo 0p.+9j 4lif the water is boiling faster?

Does an ordinary electric fan cool the air? Why w lcjkq u 1*mx)5j nz-vc3 hwd--k3l2yor why not? If not, why use it?

Very high in the Earth’s atmosphere, thb1zr.1gfp7 o, o/ btgue temperature can be 700 $^{\circ} C$ . Yet an animal there would freeze to death rather than roast. Explain.

Explorers on failed Arctic expediti4w /yc4l or0v(j*)fw(aobap (zb1s mdons have survived by covering themselves with snow. Why would they do1d/j bzrl4vb)cm (y*p ( 0fwaa s4(owo that?

Why is wet sand at the beach cooler to w /v9cb,f**syp8v.56sb qp g ewvn ukr2alk on than dry sand?

If you hear that an objezdu3a mx0u 5 n/t,q6ozct has “high heat content,” does that mean that its temperature is high? Explai3zxto,z/5 au 0mqdun6n.

When hot-air furnaces are used to heat a house, why is it important that thep8a+ zdnvvz6h3pj*r9d7h x. sre be a vent for air to return to the furnace? Wha9+ dz68.p7h srjxva*zpnvhd3t happens if this vent is blocked by a bookcase?

Ceiling fans are sometimes reversible, so that they drive the air down ini -5bb.cz xhvw(l k44m one season and pull it up in a4zkh.4v(-bw ixlcm5 bnother season. Which way should you set the fan for summer? For winter?

Down sleeping bags and parkas 8 ,l:bo-w0srjviuujn kj-1o4 are often specified as so many inches or centimeters of loft, the actual thickness of the garment when it is fluffed up. Ex-1,vi k0os : ul8-rj bjoujwn4plain.

Microprocessor chips havedpcud(.f(9kb a “heat sink” glued on top that looks like a series of fins. Why id(f9(duk cp .bs it shaped like that?

Sea breezes are often encounmbgi5zq jh4d 7g, *cd:tered on sunny days at the shore of a large body of water. Explain in light of the fact that the tempera4i jh,7qg5b cg *:ddzmture 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 s7xpf 31coro sjf/n,1b vz;w+is often cooler o17c3 rbw;vxfszn, p/fj 1s+othan a floor that rests 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 tempera.5 nehk czzg982vee); syehr sye:1 c5ture readings are always taken with the thermometer in the ) e ;nescvcrgz:ee h92 15s. zeyh8ky5shade.

A premature baby in a5s 6bt: 5 ozit,rcjj(2n-f jnn3lmwg1n incubator can be dangerously cooled even when the air temperature in the incubator is warm flt,-wj651: sjjmgtnnc253br z i(n o. Explain.

Why is the liner of a thermopcpa :(r 1sdc5gxnnks8i/ 7o fqi2):zs bottle silvered (Fig. 14–15), and why does it have a vacuum dpq5p sfs(in1 /ga82ncirzc:x):7 k obetween its two walls?

Imagine you have a wall+ef +xo1egg ktj(ik0/ that is very well insulated — it has a very high thermal resistg e(i /x+0ktj+f1 gekoance, $R_1$ 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 proce7 fs19)xzz mlips4 4x29ckce esses: (1) ventilation around edges; (2) through the frame, particularly if it is metal; (3) through the glass panes; and (4) mk2lxie f c)p9 s147z4x9 scezradiation. (a) For the first three, what is (are) the mechanism(s): conduction, convection, or radiation? (b) Heavy curtains reduce which of these heat losses? Explain in detail.

A piece of wood lying in the Sun absorb 0sqf:7) k2tb yhynhdtd9t.8soj2 hd)s more heat than a piece of shiny metal. Yet the wood feels less hot than the metal when you pick it ud 2)ts80yt.d 7 2bst:okjqny)9dh fhhp. Explain.

The Earth cools off at night much more quickly whe 68 -iyiruncn-n the weather is clear than when cloud-ucyr ni6 -n8iy. Why?

An “emergency blanket” 8n/52 hhpbi iub fnjy06e-w( wis a thin shiny (metal coated) plastic foil. Explain how it canyei5h w fnb -p0hw(28/bu6jin help to keep an immobile person warm.

Explain why cities situated by the ocean tend to have les/7:ot8tqt)t2rmdi g -6js 9 nue6ucows extreme temperatures than inland cities at th6t/oc 2s 8otnwruu megidjt79q 6t-:)e same latitude.

  How much heat (in joules) is required to raise the temperaj)bgy 0:q59edto(ex vture of 30.0 kg of water from0bq5:xvde )9tg o(ej y 15 $^{\circ} C$ to 95 $^{\circ} C$ ?    $ \times10^{7 }\,J$

  To what temperature will 7700 J of heat raise 3.0 kg of32e*xo(ia jjif 1r xq* water that is initially at 10.1o rq2(ifeaj3* *ixjx0 $^{\circ} C$ ?    $^{\circ} C$

  An average active person consumes about c9mm;coem 7-dmv9o2t 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 (Btubat2ipk z+t2ui9r e2) j50tkv) is a unit of heat in the British system of units. One Btu is defi 5rj0ke)uviptt2 bt29+ ki 2azned as the heat needed to raise 1 lb of water by 1 F $^{\circ} $ . Show that
1Btu = 0.252kcal=1055J

  A water heater can genera jmqdy4ya5* g87z/va rte $32,000\,kJ/h$ 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 takfnx2jv3) j)8b g))xi y. tsuxxe to heat a cup of soup (assume this is)jsx 8)bn))gixvtf3 2u.xjyx 250 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-kg ; v st 5cwg*zrej06v:zcar to rest from a speed of ev ;:jt05zwz6gr s*c v$95\,km/h$ ?    kcal

  An automobile cooling system holds 16 L of wateun-k1 d2bl 6+h6rzf8ipa s ) jmhm-a(yr. How much heat does it absorb if its temperat28lmk p-)f1j-66ynhm sra +ua(z dh biure rises from 20$^{\circ}C $ to 90$^{\circ} C$?    $ \times10^{ 6}\,J$

  What is the specific heat of a metal substance if 135 kJ oc7ap3 w,i ywc6b+a8s af heat is needed to raise 5.1 kg of the metal from 18.0 cy paa,6+sia38wbc7w $^{\circ}C $ to 31.5$^{\circ} C$ ?    $J/kg\cdot\,C^{\circ} $

  Samples of copper, aluminum, and water experience thwk au ,3swfzahlq21;7 e same temperature rise when they absorb the same amount of heat. What is the ratio of their masses? [Hint: See Table ,uw saf273l;1q wkh za14–1.]$m_{Cu}$ : $m_{Al}$ : $m_{H_2O}$ =    :    :   

  A 35-g glass thermometeys u*0pufq2 u4tx,njyy/2 zv 7r reads 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(0lrjn;zg-.zelh35 l* ts cnk en 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 (mass = ;n+g aruka*st8-atlzorb; ; )$0.4\,kg$) 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 heatedkhsd p,i vee .;i3yn03*v0rp0 2ktvfc 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 boidsvk0x by0t r3 99 xp02isl*qdl 0.75 L of water initially a90tp q 0 2s3yrsxdv0 xkd9bil*t 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 fromjzrzy. l;4)f, m ydx(y 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 zz(j,lrd;xy.yf y4m) initial temperature of the mixture is 15.0$^{\circ}C $ , and its temperature after ignition is 53.5$^{\circ} C$ .    Cal

  When a 290-g piece of iron at 180 xvdbchs pf-s7b/eq)9; z+ lz8$^{\circ} C$ 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 ha hz*lu/ iq qx7;mzdqu8c0iu2;mmer 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 di2y1 dhvjk+ c1efined as the amount of heat needed to raise its temper ijkd c+1h2v1yature 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 t 6k+z0f,lbs i ysq 5j ),5hvbvms2hr;that is initially at 20$^{\circ} C$?    $ \times10^{6 }\,J$

  A 0.095-kg aluminium sphere is droppeiwqvn3 hrh2 l *k/jerm.9p07x d 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 incr *3/lrv 7 nwmhphej0.kxi92rqease?    $C^{\circ}$

  During exercise, a pers 1kek; xcb5pi :csa 4/q:jkwg9on may give off 180 kcal of heat in 30 min by evaporation of water from the skin. How much water has been :c ek/:i1kxc4gkap5w 9s ;jb qlost?    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 container ofwx815 dpbuopweb+gha)m*; * c liquid nitrogen. How much nitrogen evaporates if +b peo ugwm*5pa xhwc;)d81*bit is at its boiling point of 77 K and has a latent heat of vaporization of $200\,kJ/kg$ Assume for simplicity that the specific heat of ice is a constant and is equal to its value near its melting point.    kg

  A cube of ice is taken from the freezer at sp8v qmb(g//w + f1(ydvi l8wd-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 18qzp;g ymo,09kmmdl 409xg mj,$^{\circ} C$. 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 consumesivc:b2s59 jtao)f nv6 8.0 L of water over the span of four hours. Making the approximation that all of the cyclist’s energy goes into evaporating this water as sweat, how much energy in kcal did the rider use during the ride? (Since the efficiency of the rider is only about 20%, most of the energy consumed does go to heat, so our approximation i62ja t cb :svinf)v9o5s not far off.)    kcal

  What mass of steam at 10jl+tng pgn/a+ t. t-9f0$^{\circ} C$ 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 mercurf0du fk(xt67py 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 travelivfijfti4 / ,(bng 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 2elov-5/ avvao db, r4moving 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 inve- tjnkx49t +3 uillnu2stigator notes that the 8.2-g lead bullet that was stopped in a doorframe apparently melted completely on impact. Assuming the bullet was fired at room texnkunl -tj ut il92+34mperature (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 ofy;fj.7jec93 +5z; lmaavcjuz 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 t 5epz 99rvhid1hat there are strong gusty winds and the external temperatp9hzv9dr 1ei 5ure is -5$^{\circ} C$   $ \times10^{4 }$ W

  (a) How much power is radiated by a tungsten sphere (emissbu +bs2,0ydnqivity $e\,=\,0.35$) 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 cs 5gx51zdwuy 9amxiupbb5juq2 0/7 l1onduction from the blood capillaries bu 9 b2z5 lgj1upx0idb/ wa55uym s71xqeneath 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, share a 12-cm-thic.ro 8pic nh;g+k brick wall. Because of a number of 100-W lightbulbs in one room, tg. 8o hi+c;pnrhe 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 blow7lw i8g- wcd(brghq9 a (y17tck 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 aluef b .gpt /rdft*uy f95arbrl1 84ow4,minum rod of the same length and cross-sectional area are attached end to end (Fig. 14–ypr f8al4u95go*1rd rtf 4b t /wef,.b18). 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 rt c:7d+1sod omate at which the whole Earth receives energy:soc t1do+d7 m 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, which is dissipated through a glass xafxp;oz d15nnqhr;ap(:1 vh gy;hl6og02z5bulb that hasqnp1g(x; pz6 h nv z ;l5oxh:;ro5hd1ayagf0 2 a radius of 3.0 cm and is 1.0 mm thick. What is the difference in temperature between the inner and outer surfaces of the glass?   $^{\circ}C $

  Suppose the insulating qualities of the wall of a house come mainly f 2k-e2 +mm2fvvtek* aprom a 4.0-in. layer of brick and an R-19 layer ofvvmk 2ta+e22k f pm*-e 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 windq;aqs08mw+p9b c vd0k ow has two panes of glass separated by an air space, Fig. 14–20. (a) Show thawd; 0 9k0p+maqqbv8cst 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 11.0 kg 4 9a;g r l)chw,2 8znqnm:feduxhs4:n 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 aboutrjf i j b2uxkiufn1a*1 c :-+f;sklj-) 0.20 kg of liquid at 5$^{\circ}C $. Drinking this liquid can actually consume some of the fat in the body, since energy is needed to warm the water to body temperature (37$^{\circ} C$). How many food Calories should the drink have so that it is in perfect balance with the heat needed to warm the liquid?    C

  If coal gives off $30\,MJ/kg$ when it is burned, how much coal would be needed to heat a house that requires $ 2.0\times10^{5 }\,MJ$ for the whole winter? Assume that 30% of the heat is lost up the chimney.    kg

  To get an idea of how much therlvld * aztg: t.-int/2mal energy is contained in the world’s oceans, estimate the heat liberated when a cube of ocean water, 1 km on each side, is coolelz-t:/nvt*l. t2gad i d 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 anjsmg ql m,1ax9fv436tb3k /k fixed 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 temperature6,31k4/t9 qmlnf3sx ajbm kgv 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 5-(q h fn,3a; osschws 4(bpfxe)wdb)Sun, assuming it to be a per,s- fn4 xf hbqd; bsw5ew)(ahposc( 3)fect 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 mayzer aq/x* *e9j 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 the tooqf9yb;z tancw ja2 x4n3if2 a5z;y20 p of a cliff and falls a vertical height of 140 m before striking the ground. Estimate the temperature ris 03ta ;9y2 nzbanozf;q w2ajyc54x2fi e of the rock if 50% of the heat generated remains in the rock.    $C^{\circ} $

  A 2.3-kg lead ball is dropped into a 2.5-L insulated pail of water initiallys/ 6-f;x/7b dd cynvbg at 20 bfxcsy7b; dvdn /-6/g.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 jaczb,hr5 uljh ,*ket 3.5 cm thick with total surface area ,rlz 5hb, uhj*$1.2\,m^2$ 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 rate of ff*ttiab6di)+k u6/n4d c+n p 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 atkl3iugcs,1 .c which heat can be conducted from the interior of the body to the surface. Assume that the thickness of tissue is 4.0 cm, that the ski ui3.gk1s,l ccn 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 o/s7 wt 77j*pd f,bsmcaref,7m7w/sjtcs b7 *o dpa $410\,m^2$ 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 travelinvl 8 h 086d3dgdezwp7hb)e(wv7qzv 5ig 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 :*ky;jfnq6 yqp;f uys(tjd.7jg r5z0 into account radiation from the leaf to calculate how mucygprjjj 60;u fdzky5 7yf.n q:(*q;sth 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 i3mnm*ijnb8 h )ts initial temperature was - n*j8hmm3)b in125$^{\circ} C$ 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 Ea kkdk8 ;;; kjr2l gzy55pw:hzxrth’s crust increases about 1.0 C$^{\circ} $ for each 30 m of depth. The thermal conductivity of the crust is $0.80\,W/C^{\circ} \cdot\,m$
(a) Determine the heat transferred from the interior to the surface for the entire Earth in 1 day.    $ \times10^{18 }\,J$
(b) Compare this heat to the amount of energy incident on the Earth in 1 day due to radiation from the Sun.$Q_{Sun}$ =    $ \times10^{4 }\,Q_{interior}$

  In a typical game of squash (Fig. 14–22), two people hit a soft d g6s6kr.xv:ryax; yt5;ixg+ rubber ball at a wall until they are about to drop due to dehydration anisytxx dy6 6r;.:gka r;+5gvxd 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 w:35mbaxxpsq *hen equal masses of ice at 0$^{\circ} C$ and steam at 100$^{\circ}C $ are mixed together?

  In a cold environment, a persvp (qvm2gy)) oon can lose heat by conduction and radiation at a rate of about 200 W. Estimate how long it qp()m vg 2yov)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” left in tq65v,in7krz2ewt :n hj. 2b rxhe 50-gal (185-L) water heater. This suggests tha:br 225tez xrnk7,whi. v6jqnt 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 surfaukx8s (nvf)ml-5hqa e d8. j5tce 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.    $^{\circ} C$