What happens to the work done when a jar of orange juice is vig d50l .bn4k3eg fnji8o/eax x)orously shaken?

When a hot object warms a cooler object, does temperature flow be *cribbhke5 )6tween them? Are the temperature changes of the two objects 6b *re cbih)k5equal?

(a) If two objects o tw. iy/annz-y)q7te 48tl1p*)puctkf different temperatures 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 interiau t)4qy tye *wlct-1.z/8k pn7 tp)nnal energies of the two objects are the same? Explain.

In warm regions where tropical plants grow but the temperature may drop below fro 7ne7 q1dty1deezing a few times in the winter, the destruction of sensitive plants due to freet yd n1e7o1dq7zing can be reduced by watering them in the evening. Explain.

The specific heat of water is quite large. Explax r6ze9 hv-7jrsc( kq.in why this fact makes water particularly good for heating systems (that is, hot-water radiators.e-sz6( vr9x hk jrq7c).

Why does water in a metal canteen stay c gl)crp/);cwwooler if the cloth jacket surrounding the cwgprlc)w;c )/ anteen is kept moist?

Explain why burns caused by steam on the skin are often more sevejj; mrqrm -6q.re than burns caused by wa.mq ;j6mrj- rqter at 100 ${}^{\circ }C$ .

Explain why water cools (its temperature drops) when it evaporates, usix/pao+e971yy4ydut i+ d yl(qng the concepts of lateodtu(4q+iy7/y9adp +yxe1l ynt heat and internal energy.

Will potatoes cook faster if the wakb* fno6s b l nw7pzjl1r:k8;9ter is boiling faster?

Does an ordinary electric fan cool the air? Why or why not? If nmvvsyxz 66 /2ki qqp7/ot, why use it?

Very high in the Earth’s atmosphere, the temperaturf-o-o;1a 4uw gxtxsb(e can be 700 ${}^{\circ }C$ . Yet an animal there would freeze to death rather than roast. Explain.

Explorers on failed Arctic expeditions have survived by coveri , 80pl qas2w:o(kpzmzng themselves with snow. Why would twzosq lk,a2:p 80(pzmhey do that?

Why is wet sand at the beach cooleea1 v bw4sh4/h:vre/sr to walk on than dry sand?

If you hear that an object has “high heat contenten 8f/ 6-cs3yd:bv bsk,” does that mean that its temperature is highd s /c8n -bv:ekyb63fs? Explain.

When hot-air furnaces are o trpgvm+tv 6xz3o2p2 4q9tw8used to heat a house, why is it important that there be a vent for air to return to the furnace? What happenz28vqtp42 port6g3o + wmtx9vs if this vent is blocked by a bookcase?

Ceiling fans are sometimes reversible, so that they drive the air do- id afz8j(,z-4khgf obo)qe. wn in one season and pull it up in another season. Which way should you set the fan for summer? Forzfaehofzi8- (bg-qd)oj , .k4 winter?

Down sleeping bags and parkas are often specified as so many inches or centimetkjt(qe9 v8ej)dw s8b0x52b i n-tar;uers of loft, the actual thickness of the garment when it is fluffed up2e9xird8nj0uw a ve (b;b-skt8)5tq j. Explain.

Microprocessor chips have a “heat sink” glued on top that lopu(y g 8ny ea(0d0t+ugoks like a series of fins. Why is it shaped like th(uteya g +n0p ygu0d8(at?

Sea breezes are often encountered on sunny days at the shore of0bm i(,ha ke1c8*xz lf a large body of water. Explain in light of the fact that the temperature of the land rises more rapidly lm a0fz8(k * b1xcih,ethan that of the nearby water.

The floor of a house on a founo8 ok( +vocap5vuf-o-dation under which the air can flow is often cooler than a floo-afo+( 8pvu5o- ovk cor 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 temperature readings are )ec4i0u f:qsg yhb(:6dreci 3f x4s6dalways taken with the thermometer in the4) s(yiq:g d:dei 60efhccuxr36f 4bs shade.

A premature baby in an incubator can be dangerously coolyv .kygf -n 6et6h,7o*msx rv1ed even when the air temperature in the incubator is warm. 6 sy6vy-*t,h onf7egv 1m. xrkExplain.

Why is the liner of a thermos bottle silvered (Fig. 6ov89 ti p u7r7q+dcie14–15), and why does it have 97p678qrud+ oicietv a vacuum between its two walls?

Imagine you have a wall that is very well ins9qm q3a,(msajqzxqo ( w91; uwulated — it has a very high thermal resm, s(9qq 3wumqoz;(qxa1 j9awistance, $R_1$ 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: (1) ventilation arod p.sgf7)ujk:7k;zz3 tv3x)nri b 7lm,e e d1xund edges; (2) through the frame, particularly if it is metal; (3) through the glass panes; and (4) radiatio ) b.erxvg )kf li7z3u :pm3xdkzj;sn7,te71 dn. (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 t re948svvp/ag he Sun absorbs more heat than a piece of shiny metal. Y8g p /rsve94vaet the wood feels less hot than the metal when you pick it up. Explain.

The Earth cools off at night much more quickly when the weather is ix-vhb 3dt;do mhp* y12wnu9+ clear than when clo-+t; mwi1on2d*b 9hd3xphv yu udy. Why?

An “emergency blanket” is a thin shiny (metal coated) plastic foil. Ex8w nyh:2q:w)x zoae rlh.s94bplain how it can bzox :ah9sy.w: ew8h4 rl n)q2help to keep an immobile person warm.

Explain why cities situated by the ocean tend to hav;hgb/ c(rd(yboui/k,e less extreme temperatures than inland cities at the same l/(,d/ ;ob bgkiyhuc r(atitude.

  How much heat (in joules) is required to raise the tempecezc ,4/cy,lf0y:swi fa521zobgl f +rature of 30.0 kg of water fromi5, z,c ecwa 2fczl slb/ff:04yg+oy1 15 ${}^{\circ }C$ to 95 ${}^{\circ }C$ ?    $\times {10}^{7}J$

  To what temperature will 7700 J of heat raise 3.0 kg;ylqddy / eji15/3yh p of water that is initially at 10.dil/3q1 y/y5d ;hpeyj0 ${}^{\circ }C$ ?    ${}^{\circ }C$

  An average active person consumes about 2500 Cal;x js+fs/1r3ddn 0dfi a day.
(a) What is this in joules?   $\times {10}^{7}J$
(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 (ui ijh5k h1 q 9nww,( yc.,gbdkb7)3,n)ug bitBtu) is a unit of heat in the British system of units. One Btu is defined as the heat needed to raise nwt .k9kbhcu,qi n),ig( w5ib,h g bdy)1uj7 31 lb of water by 1 F ${}^{\circ }$ . Show that
1Btu = 0.252kcal=1055J

  A water heater can ge-d,o +q,-vw4nue ydk enerate $32,000kJ/h$ 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 longgq9 j4mq2 -ny d **vcfqcn2g-a it will take to heat a cup of soup (assume this is 250 mL of water) fro4qn d2gnq*9cvmja2y *q-cfg- m 20${}^{\circ }C$ to 60${}^{\circ }C$ .    min

  How many kilocalories are generated when the brakes are used to n(k6-6qrpyc 0fqs ..d 5thx vobring a 1200-kg car n6ok50 p.qvdft.rx6ycs-hq (to rest from a speed of $95km/h$ ?    kcal

  An automobile cooling system holds 16 L of wateja5lj d3 goy6c;l sd6/r. How much heat does it absorb if its temperature rises fl/3yg 6oc; d5l js6dajrom 20${}^{\circ }C$ to 90${}^{\circ }C$?    $\times {10}^{6}J$

  What is the specific heaj r ,g,p x3yurl)5h*jxt of a metal substance if 135 kJ of heat is needed to raise 5.1 kg of the metal from 18. grlj pjr,*y)hx,3ux 50${}^{\circ }C$ to 31.5${}^{\circ }C$ ?    $J/kg\cdot C^{\circ }$

  Samples of copper, aluminbve+f/4d :pn r/rhlo0 um, and water experience the same temperature rise when they absorb the same amount of heat. What is the 0/b e/nrfophrv4 :+dl ratio of their masses? [Hint: See Table 14–1.]$m_{Cu}$ : $m_{Al}$ : $m_{H_{2}O}$ =    :    :   

  A 35-g glass thermometer rl:hxta0p )b9hp k3pw0eads 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?$T_{i{H}_{2}O}$ =    ${}^{\circ }C$

  What will be the equilibrium temperature when a 245-g blo2bn/6mkjlcdd, e(9 gs ck 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 horseshoek,.x-i7 qh*c:qr xoqv (mass = $0.4kg$) just forged (Fig. 14–16), is dropped into 1.35 L of water in a 0.30-kg iron pot initially at 20.0${}^{\circ }C$ . If the final equilibrium temperature is 25.0${}^{\circ }C$, estimate the initial temperature of the hot horseshoe.    ${}^{\circ }C$

  A 215-g sample of a substance is heated to 34 fu7mfkc b)4f30${}^{\circ }C$ 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 u tpy/j ae6q81boil 0.75 L of water initially p8ytuq aj61e /at 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 ai bgxn+l5*d(l1j-p- 4 igl cycontent of 75 g of candy from the following measurements. A 15-g sample of the candy is allowed to dry before putting it in a bomb calorimeter. The aluminum bomb has a mass of 0.725 kg and is placed in 2.00 kg of water contained in an aluminum calorimeter cup of mass 0.624 kg. The initial temperature of the mixture is 1 bl(-lj5p*gx-ci1a4lgdn + iy 5.0${}^{\circ }C$ , and its temperature after ignition is 53.5${}^{\circ }C$ .    Cal

  When a 290-g piece of e+qgzb bb*7/-urwtxc ,har6 :iron 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 *j .,z)j-qmzb, qkirwhas a speed of $6.5m/s$ 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 okam*q28ylij31.rdv0 iehgf;bject is defined as the amount of heat needed to rais*j.di0mh8 ;3i2rfl1qayevk ge its temperature by 1 $C^{\circ }$ . Thus, to raise the temperature by $\mathrm{\Delta }T$ requires heat Q given by
$Q=C\mathrm{\Delta }T$
(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?    $\times {10}^{3}J/C^{\circ }$
(c) Of 25 kg of water?   $\times {10}^{5}J/C^{\circ }$

  How much heat is needed to melt 16.50 kg of silver that is initially at 2lam/pg7 cp715rx fo 8q0${}^{\circ }C$?    $\times {10}^{6}J$

  A 0.095-kg aluminium sphere is dropped from the roof of a 45-m-high building. ui*0sd:s)timr b5 nyv-ojh:rs)kr3 )If 65% of the thermal energy pro)nyi 5m3v )brj: ssi:0u-)sk drr*tohduced when it hits the ground is absorbed by the sphere, what is its temperature increase?    $C^{\circ }$

  During exercise, a person mv s 7swgn54si7 2,((qoedj2t6qg puxeay give off 180 kcal of heat in 30 min by evaporation of water from the skin. How muc2 pdeo4(6j,q7ve 5xsw 7u gig2(qtsns h water has been lost?    kg

  If $2.80\times {10}^{5}J$ 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 melti) leeh1-nevnpnl; z2:ng point is dropped into an insulated container of liquid nitrogen. How much nitrogen evaporates if it is at its boiling point of 77 K anpl:1lee n;) ve- nnh2zd has a latent heat of vaporization of $200kJ/kg$ 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/7ohxnm,wbym.f 7; co -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?    $\times {10}^{-3}$ kg

  An iron boiler of mass 230 kg contains 830 kg of watersy1y / -d9ft tksq)b6p at 18${}^{\circ }C$. A heater supplies energy at the rate of $52,000kJ/h$ 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 8ki7, wnigut9 :.0 L of water over the span of four hours. Making the approximation that all oii7,t:wkg nu9 f 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 is not far off.)    kcal

  What mass of steam atne ud cm7.n-vy 6lan 98m7fen; 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 mp w5, t/ybb8lrercury is $138J/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${}^{\circ }C$ .    $\times {10}^4$ J/kg

  A 70-g bullet traveling 01 l3h3lujpxq at $250m/s$ 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 moom)awm sm 30um;+szx5:stki,ving at $6.4m/s$ 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 the 8.2x rq20i)uo 4lf-g lead bullet that was stopped in a doorfr x rfol24qui0)ame apparently melted completely on impact. Assuming the bullet was fired at room temperature (20${}^{\circ }C$ ), what does the investigator calculate as the minimum muzzle velocity of the gun?    m/s

  One end of a 33-cm-long aluminum rod with a diameter of 2.0 cmq/zg it4d a yywlrve)3/9r(, c 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, jh f9.wcvdlpd;5 3 2c6civj8rassuming that there are strong gusty winds and the external cl8h d;f6v cwp9dvc j 3j.2r5itemperature is -5${}^{\circ }C$   $\times {10}^4$ W

  (a) How much power is raeiy0 sk0 -ej(b.ht+xd tc*t2c diated 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 ski5kwoak.ch k.j5 x0bwu1 t up5-n. Suppose 200 W of heat flows by conduction from the blood capil1cx5 k k.5tj.ua-0uhww5pobklaries beneath the skin to the body’s surface area of $1.5m^2$ If the temperature difference is 0.50 $C^{\circ }$ , estimate the average distance of capillaries below the skin surface.    $\times {10}^{-4}$ m

  Two rooms, each a cube 4.0 m per side, share a 12-cm-thick ) 5 lvdk9o2mscbrick wall. Because of a number of 100-W lightbulbs in one rkvd) 2ol59csmoom, 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 ice at l8h+kdy3in 7)s:b v gl0${}^{\circ }C$ with a flat horizontal area $1.0m^2$ 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 twz)* qai9i9 j z)b ;ix:)dsiobhe 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 tempz9bbw)i)i :ox;z aq9 isid) j*erature 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 constanbpdi4-e .*dfub 1 dw9mt, estimate the rate at which the whole Earth receives energy from the Sunfd- w1 bbide49du.pm*.    $\times {10}^{17}$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 hikzv)tl+ usioga8d9ts 8) v/+u68b iyeat, which is dissipated through a glass bulb that has a radiusys8tv +)/z8u ba+si8 iu6)iv9 gdkt lo 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 w946oi 6n grviiall 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 it v 66iirnigo94s total area is $240f{t}^2$ and the temperature difference across it is 12 $F^{\circ }$?    Btu/h

A double-glazed window has two panes of glass separated.n ydm4s9j 9ss 3b+70urpx qep by an air space, Fig. 14–20. (a) Show that the rate of heat flow through such a window by condss+rdj 9s q097pm 3x.bn ye4puuction 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 of ice at 0(mp 5 s7sfx6mr${}^{\circ }C$ to melt when it is placed in a carefully sealed Styrofoam ice chest of dimensions $25cm\times 35cm\times 55cm$ 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${}^{\circ }C$.    $\times {10}^4$s

  A soft-drink can contains about wk q:klqoqi0zna;c/ p :0+ly0 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 $30MJ/kg$ when it is burned, how much coal would be needed to heat a house that requires $2.0\times {10}^{5}MJ$ 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 the world’s o-qnw2bd hgq;0ki:oo1a b*e p6;gcn * lceans, estimate the heat liberated when a cube of ocean water, 1 km on each side, is cooled by 1 K. (Appp 6kqoqbc2abn1i;g-he:*;w* old 0n groximate the ocean water as pure water for this estimate.)    $\times {10}^{15}J$

  A 15-g lead bullet is tested by firing it into a fixed block of wo jxidn59u03o)p sfym f)s2s:o3cyvx 8od 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 dp 53 20fv:m93ix)ys8fyxson u)scojhas a temperature rise measured as 0.020 $C^{\circ }$. Estimate the entering speed of the bullet.    m/s

  (a) Find the total power ray oj y4-+bc/rpdiated into space by the Sun, assuming it to be a perfy+rc pj-4/o ybect emitter at $T=5500K$ The Sun’s radius is $7.0\times {10}^{8}m$    $\times {10}^{26}W$
(b) From this, determine the power per unit area arriving at the Earth, $1.5\times {10}^{11}m$ away (Fig. 14–21).    $\times {10}^{3}W/m^2$

  During light activity, a 70-,0g nn w/d q .qf8ut-rzu:6kkekg 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 the top of a cliff and falls a vertical heightwn p1 ,e/94)h- mysnxbvz*tys of 140 m bpzt/ ny*s ,1ny)4m-exhvs9 bwefore striking the ground. Estimate the temperature rise of the rock if 50% of the heat generated remains in the rock.    $C^{\circ }$

  A 2.3-kg lead ball is dr hs: ihwkz7cu .agjnfc61;a2 ;opped into a 2.5-L insulated pail of water initially at 2;n :hck wai;ua csz716.hfjg20.0${}^{\circ }C$. 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 gxmhxwj ;5wcqb5l 4l6 1oose down jacket 3.5 cm thick with total surface area b5mx1q6h ljw;5lwxc4 $1.2m^2$ 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 a0ngqei3 szz/6 0g wev(verage metabolism rate of about $950kcal/h$ 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 conduf d9+6ltlk z:p)ewfi-3fm te1 cted from the interior of the body to the surface. Assume that the thicknesslf-e3 e9 :t+zm)fl1 t6idkwfp 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 $1.5m^2$ 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 kof17ow 9amo) conductivity of air) and kw) mof7ooa 19area $410m^2$ a roof of wood 6.5 cm thick and area $280m^2$ and uncovered windows 0.65 cm thick and total area $33m^2$
(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${}^{\circ }C$    $\times {10}^5$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 $750m^3$    $\times {10}^8$J
(c) If natural gas costs 0.080 dollars per kilogram and its heat of combustion is $5.4\times {10}^{7}J/kg$ 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 $0.24kcal/kg$$\cdot C$.    dollars

  A 15-g lead bullet travelingj7ja pd9cz0-s at $220m/s$ passes through a thin wall and emerges at a speed of $160m/s$ 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 $40c{m}^2$ and mass $4.5\times {10}^{-4}kg$ directly faces the Sun on a clear day. The leaf has an emissivity of 0.85 and a specific heat of $0.80kcal/kg\cdot K$.
(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 radia xc c(va5+ k0sw1/ebzition from the leaf to calculate how much water mustb (z0+csv ice/ 1awx5k be transpired (evaporated) by the leaf per hour to maintain a temperature of 35${}^{\circ }C$.    g/h

  An iron meteorite melts when it entersj8+(0vzim yxu the Earth’s atmosphere. If its initial temperature wasu(0x+8mzjvy i -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 t,;2mmty9m nz khe Earth’s crust increases about 1.0 C${}^{\circ }$ for each 30 m of depth. The thermal conductivity of the crust is $0.80W/C^{\circ }\cdot m$
(a) Determine the heat transferred from the interior to the surface for the entire Earth in 1 day.    $\times {10}^{18}J$
(b) Compare this heat to the amount of energy incident on the Earth in 1 day due to radiation from the Sun.$Q_{Sun}$ =    $\times {10}^4{Q}_{interior}$

  In a typical game of squash (Fig. 14–22), two people hit a soft rub7:9z ckfcev3t ber ball at a wall until they are about to drop due to dehydration and exhaustion. Assume that the ball hits the wall at at:9ccf37 zkev velocity of $22m/s$ and bounces back with a velocity of $12m/s$ 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 $1200J/kg$$\cdot C$)    $C^{\circ }$

What will be the final result when equal m/qtqhb i,-zf:at ha-urf)7 1vasses 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 conduction and radiatiooa.90gax9 fxr2g t 1kc;b,vxfto1rw0 n at a ra9ka,vf.1x;xg 2r10ttowaxc ogr9 b0f te of about 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” left in thk i ,;(5-pudm,6ftzffoe 4i /by 0kneoe 50-gal (185-L) water heater. This suggests that the tank has ei ; 6bf(m tkuen ,p4,o-o/y0fkied5fzmptied and refilled with water at roughly 10${}^{\circ }C$. (a) How much energy does it take to reheat the water to 50${}^{\circ }C$? (b) How long would it take if the heater output is 9500 W?    s

  The temperature of the glass surface of a 60-W lightbuuv8h 1ik*x 3kpcdf*a( lb 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.    ${}^{\circ }C$