What happens to the work done when a jar of orange juice is vigorously shaken? h*v rxllg83/u

When a hot object warms a cooler i 8/u -xvdvx.uobject, does temperature flow between them? Are the temperat. xd-xiv8uuv /ure changes of the two objects equal?

(a) If two objects of different temperyhnb0r:r zg6k9q0vi w+ f6ol3atures 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 if0 : zq6k+0vrwgblf o 639yhrin the internal energies of the two objects are the same? Explain.

In warm regions where tropical plants grow but the tempqb2fk9yv 9:tm64e meo erature may drop below freezing a few times in the winter, the destruction of sensitive plants due to freezing can be re9 tb e4kq2o6mfve9:ymduced by watering them in the evening. Explain.

The specific heat of )pq0 )ytro1k pqk6z5jk7;xot ep*k:owater is quite large. Explain why this fact makes water particularly good for heating systems (that i1k0yt p :k* qkjop;k qo6)ot75)rexpzs, hot-water radiators).

Why does water in a metal canteen stay cooler if the cloth jacket sin na)t(p,ocw5 9okn;urrounding the cann oaio9(pn) 5ckwn t,;teen is kept moist?

Explain why burns caused by 2e5hle s oeqaq.l: 55hkt;t-r steam on the skin are often more severe than burns caused by water at 5eot5qhr2e: ht-5 kqa.;lels 100 $^{\circ} C$ .

Explain why water cools (its t1v n;j:q.2uk zpu tf,temperature drops) when it evaporates, using the concepts of la q;1jtuf2.v ,npuz:t ktent heat and internal energy.

Will potatoes cook faster if the water va8jg t5:bwv tdaq1vq k: n4):is boiling faster?

Does an ordinary electric fan cool the air? Why ocv.un n3,0guz, 9 ofrnr why not? If not, why use it?

Very high in the Earth’s atmosphere, the temperature can ny,,0 bu; ztzlbe 700 $^{\circ} C$ . Yet an animal there would freeze to death rather than roast. Explain.

Explorers on failed Arctic expi vhu:*ucw *plon :+is, ed-+seditions have survived by covering themselves with snow. Why would they do that?*suu-, cp+iihn:: ovsde +wl*

Why is wet sand at the beach cooler to walk on than dry san*q qpwb5,xy)o 6n;u9pfut mn(d?

If you hear that an object has “high heat content,”i /a dpgpa1q0g,v-w*nyh 8;mi does that mean that its temperature is higp-q id,ymwai 0gp n;/ 18g*vhah? Explain.

When hot-air furnaces are used to heat a house, why is it imz 73s,kx4w6oeutky z,+l.mhb portant that there be a s y,h3zm.7 tlubxzoe+4k k,6wvent for air to return to the furnace? What happens if this vent is blocked by a bookcase?

Ceiling fans are sometimes reversible, so that they drive the air d9pvwwazj- :7down in one season and pull it up in anotherz-:djp7a wvw9 season. Which way should you set the fan for summer? For winter?

Down sleeping bags and pq1i w7u)d p vqpoe(*jvj7sc jw/.7 d7karkas are often specified as so many inches or centimeters of loft, the actual thickness of the garment when it is flufq e d1s7 i/.cuqj*j7ww( 7vv)pdo pjk7fed up. Explain.

Microprocessor chips have a “heat sink” glued on top that looks like a r;7.y mfn3kqaseries of fins. Why is it shaped like 3 ;.7mrqyfkna that?

Sea breezes are often encountered on sunny days at the sho:hy31(amd* 0 lmjbg vnre of a large body of water. Explain in light of the fact that the temperature of thb0a*13 j(mnh dy vmlg:e land rises more rapidly than that of the nearby water.

The floor of a house on a foundation under which h(:3iouv4uobbe0w7/y- apgo the air can flow is often cooler(v yi3/ob0:oh be -g4uapou7w than 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 temperature ru8bd3 xp,n/3xukp ye.e8c29: pb diijeadings are always taken with the thermometer in the jpd,92ii.e 3u uxpk3 n/ybc: bpd xe88shade.

A premature baby in an incubatr +9tl *7zeko7k(je moc7bi1i-6yfg por can be dangerously cooled even when the air temperature in the i+moeo-ci tgb9k7kf *ipez 77y(j1l6rncubator is warm. Explain.

Why is the liner of a thermos bottlec .et 82rr;ldeduwi 8* silvered (Fig. 14–15), and why does it have a vacuum between its two wal.di82 rt red ewu;c8l*ls?

Imagine you have a wall that is very well insulated — it has taeg;8w9ie m*4g, e zua very high thermal rew9*teez e g8g; au4mi,sistance, $R_1$ 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) ventily *ug ch ofam-,;0ii1bation 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 b-m* g hcioa,u1f ;0iymechanism(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 absorbs more heat than a piece of shiny metaldmj 4v nzx(vcy1 x8+(g. Yet the wood feels less hot than the metal when you pick it u vg(j dm(4+xxy 8vcn1zp. Explain.

The Earth cools off at night much more quickly when the weather is clear than y 3xidt4a lb, u;eki8hq3+5py when cloudy. W;ab8pt4li3udyqkx e5+ h ,i y3hy?

An “emergency blanket” is a thin shiny (metal coated) plastic foil. Explain how 8tifb*ls4hbcx +vwvqi13j4mx, a h5 2z7l lp/ it can help to keep an immobile person wa5 a3q vmifs+v /p8 1t,cjhx4*2lbl zw7lbxhi4rm.

Explain why cities situated by the ocean tend to have less extviu m5r)n6 ,tzreme temperatures than inl r5,n vm6i)uztand cities at the same latitude.

  How much heat (in joules) is required to r2g.d)s1wkkis6 i oh;i aise the temperature of 30.0 kg of waterid.ssh o6kg1 ik;i w2) from 15 $^{\circ} C$ to 95 $^{\circ} C$ ?    $ \times10^{7 }\,J$

  To what temperature will 7700 J of he6i d2sf:epjv/y rl48kat raise 3.0 kg of water that is initially at 10.0 p4/8ksljryvid:e2f 6$^{\circ} C$ ?    $^{\circ} C$

  An average active person consumes about 2500 Cal a d ms4.kl 318tfh8 3wymxtuh)g jay.
(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 skc ya)zh5c :v9xeq,bvh75 .saystem of units. One Btu is defined as the heat needed to raise 1 lb of waterq9ycav, 5 7.)zkh vsaeb cx5h: by 1 F $^{\circ} $ . Show that
1Btu = 0.252kcal=1055J

  A water heater can generate jxduz/deow; .9c* k2o $32,000\,kJ/h$ How much water can it heat from 15 $^{\circ} C$ to 50 $^{\circ} C$ per hour?    kg/h

  A small immersion heater ynzs)w7:, h xs1mp)bu is rated at 350 W. Estimate how long it will take to heat a cup of soup (assume x)s)nuyz sh1:p w,7bmthis is 250 mL of water) from 20$^{\circ} C$ to 60$^{\circ} C$ .    min

  How many kilocalories a8p w0kj)dd v lo.2) .vovi2sf7l8f vodre generated when the brakes are used to bring a 1200-kg car to rest f 2lof.2dv lo) spo.8di0v)8jvf kd7wv rom a speed of $95\,km/h$ ?    kcal

  An automobile cooling sqml.l2:8czulfnzd d3 ub-6uvk rh7n1c4 +q;e ystem holds 16 L of water. How much heat does it absorb if its temperature rises ue:kl4cdnuq . cqu8 3f2;1lvb6lh-7z+d mz nrfrom 20$^{\circ}C $ to 90$^{\circ} C$?    $ \times10^{ 6}\,J$

  What is the specific heat of a ; 4+/dp s u/ytm(yk7osau* 2 onpnv(qsmetal substance if 135 kJ of heat is needed to raise 5.1 kg of the metal from*o 7nssvno((p s +yu; q/2 ptkd4u/yma 18.0$^{\circ}C $ to 31.5$^{\circ} C$ ?    $J/kg\cdot\,C^{\circ} $

  Samples of copper, aluminum, and water experience the same temperature1 a3xo. xqddk+ rise when they absorb the same amount of heat. What i3kxq+d1 oaxd .s the ratio of their masses? [Hint: See Table 14–1.]$m_{Cu}$ : $m_{Al}$ : $m_{H_2O}$ =    :    :   

  A 35-g glass thermometer readsi86;z:eoie c i 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 whmwrg : tj6cg)9 s8so,fen 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 (mgqm3 d b6 ,uxu n *e1;s,3xd;tk9ytklvass = $0.4\,kg$) 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 heatezo:bz,u g)j/lmc f4z) d to 330$^{\circ} C$ and then plunged into a 105-g aluminum calorimeter cup containing 165 g of water and a 17-g glass thermometer at 12.5$^{\circ} C$ . The final temperature is 35.0$^{\circ} C$ . What is the specific heat of the substance? (Assume no water boils away.)    $J/kg \cdot C^{\circ} $

  How long does it take a 750-W coffeepot to bring to a boil 0.7k. 4) burow9yrswgo rorv,-6,5 L of water initiaw 6.u,b sr-g,owrr)rovo9y4k lly 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 6i5wgchz8lu7 touu gocg ) (1z)c1oq8content 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 placediowu zc)g o( 7quz8o 1chu6l)81cgt 5g 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 ironjkuzt t6k8um+,y u.a8* g:gde 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 haud5 jio pp5 v,0fs91wcmmer 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 ai n;cwq,j2 -+r gdx9bys the amount of heat needed to raise its tem9jq;d xc,-+w2 ingrybperature 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 inith9xklo 3 -t 4 fi/zt4fou)fpm)ially at 20$^{\circ} C$?    $ \times10^{6 }\,J$

  A 0.095-kg aluminium sphere is dropped from the roof of a 4)ug) gj c.k+ji5njj2b5-m-high building. If 65% of the thermal energy produced when it hits the ground is absorbed )u5 jj2jbigk.g +c jn)by the sphere, what is its temperature increase?    $C^{\circ}$

  During exercise, a person may give off 180 kcal of heat in 30 min by ep tc8bn:d9ju3g(.gm zvaporation of water from the skin. How much water has been lostu (bncgp jdgt9zm8 :3.?    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 insulatecetq(l n.q,f,d (5wao d container of liquid nitrogen. How much nitrogen evaporates if it is at its boiling point of 77 K and has a latent heat qcolwd f., 5( ,qnae(tof 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 -8.jph*dexn s :zga/d /3ye/by*9gn.sc : 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 83d6jtc5r i4-x z0 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 conq6rgae g;my4 /sumes 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 a 6eq 4/rg;mgyride? (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 10042yazx8 znv 4 *(dzfkk$^{\circ} C$ 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 i- xd j *uzobx,.cyr-5ys $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 travelin sv3r:i-g1uh3i q1 zpnude *2kg 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 movi j9cczz 9gdtgoj.lc9z 1:0+gb ng at $6.4\,m/s$ glides to a stop. Assuming the ice is at 0$^{\circ} C$ and that 50% of the heat generated by friction is absorbed by the ice, how much ice melts?    g

  At a crime scene, the forensic investigator notes that the 8.z7l.mr( m 2rfd2-g lead bullet that was st.z7(rr fmlm2 dopped in a doorframe 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 diamethauc 9 m- dzhx/wm67h;er 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 - dg*.ljeakim*hj4k-:*j. tcd ay5rtthat there are strong gusty winds jm*rj*.:-iehd4d gy*k5tk t-a aj. cl and the external temperature is -5$^{\circ} C$   $ \times10^{4 }$ W

  (a) How much power is radiated by a tunh9p w,)31jc e1wdrh6g azxe z)gsten 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 s:,h52uji a mo: +kzdcvv 2n8uheat flows by conduction from the blood capillaries beneath the skin to the body’s surface ars 5dh+jva2v2m n 8u:ui: ckz,oea 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, sd(bc65ayai j,hare a 12-cm-thick brick wall. Because of a number of 100-W lightbulbs in on (aj5ci d,ab6ye 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 o5qn gv-m efzg*b/ eh,;f 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 a6k4,sj x7bzi4f eyf 9cluminum rod of the 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 constb4 z6,fj4y ixe fs9c7kant 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 at which the wholujo* v sj,1.ofc3 we p,gd,rr-e Earth receives enepr .s,vud*g 3,w-erojfo,c1jrgy 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 dissiprqwo81 +ombf* qi5u(aated 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 and outer surfaces of the glass?q8(rba5qw+f mi u*o 1o   $^{\circ}C $

  Suppose the insulati1 uk2 sola3-9hkk i2xdng qualities of the wall of a house come mainly from a 4.0-in. layer of brick and an R-19 layer of insulation, as shown in Fig. 14–19. What is the total rate of heat loss through such a wall, if its total akshl9-ioa ux2 kk 2d13rea is $240ft^2$ and the temperature difference across it is 12 $F^{\circ} $?    Btu/h

A double-glazed windo.oz9,u oejz .f9ns 3ha sf93nuw has two panes of glass separated by an air space, Fig. 14–20. (a) Show that the rate of heat flow through such a windo9nua o3js.9 zn,uf3s9z. oefhw 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 takej;;,q3qzcne+eu ee f , 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 liqk1s6/gm2xlu)l b ko7kuid 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 the world’s d tsn:jjgv9 wz2w5*5zoceans, estimate the heat liberated when a cube of ocean water, 1 km on each side, is cooled by 1 K. (Approximate the ocean water as pure water for thissz5g zdv9tj w j*5w:n2 estimate.)    $ \times10^{ 15}\,J$

  A 15-g lead bullet is 3vm 0bkczd0pyt+k )ctlq/ 4 5htested by firing it into a fixed block of wood with a mass of 1.05 kg. The block and imbedded bullet together absorb all the heat generated. After mc )vpybktqd/50+ kthcz l034thermal equilibrium has been reached, the system has a temperature rise measured as 0.020 $C^{\circ} $. Estimate the entering speed of the bullet.    m/s

  (a) Find the total power radiated inq2 w .- bl1cc,3aunsloto space by the Sun, assuming it to be a perfect emitter cwq na.u2cl o 1s3l,-bat $T\,=\,5500K$ 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-k )ppko g ksnniz)+h2ak823.gtg 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 rn0d s s)npg ,)8y5n1n zf.abvpolls off the top of a cliff and falls a vertical height of 140 m before striking the ground. Estimate the temperature rise of the rock if 50% of the heat gene18pnn f0.zs5)ns vd ypgan,) brated remains in the rock.    $C^{\circ} $

  A 2.3-kg lead ball is dropped into a 2.5-L insulated pail of water initi8 xjd6,mxl6.zi m pssuz,.bh0ally at 20.0bzh xsp8zu60 ,ds.6 ijl.mmx,$^{\circ} C$. 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 surface hmdsn hj .(na84ys58jarea jmd4hh(j5s8n. n8ays $1.2\,m^2$ 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 a75y n 67qieqwnbout $950\,kcal/h$ 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 froat +xl6wtnlw)8)u/x(py r vy/ffyh6+ m the interior of the body to the++w /uwp tx)6fv)f/y8 tya( ylhnx 6rl surface. Assume that the thickness 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 wall6sj6+- k hw 0 io:y,8thjydumus 17.5 cm thick (assume conductivity of air) and area,t hjiwku0msd-8j :hu+6 y6oy $410\,m^2$ 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 trilvo gzym ,4+mg -4ur8aveling 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 intkk 4,b3gyzl:n o account radiation from the leaf to calculate how m bzg ky4,n3lk:uch water must be transpired (evaporated) by the leaf per hour to maintain a temperature of 35$^{\circ} C$.    g/h

  An iron meteorite mel d;rhl+ rc8ed8ts when it enters the Earth’s atmosphere. If its initial temperature8 l ;8d+rcdehr 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’d vavhgh nw6nj pa: :36z-1h:os 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 rubber ball n2b4ti ti1fc+liw c*, at a wall until they are about to drop due to dehydration and excwcf l*4n+tt1iib, 2 ihaustion. 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-s b(wt a /jx:/q8cblc equal masses 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 co/ 58esd c:f.a wwls6vqnduction and radiation at a rate of about 200 W. Estimate how long it would take for thea:6.c/dv w qs lwf8se5 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 andyj/o)u.hvj:n/a5 vja dishwashing, there is “no hot water” left in the 50-gal (185-L) water heater. This suggests that the tank has emptied and refilled with water at roughly 10.vy/ov hn: aau)/j5 jj$^{\circ} C$. (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 li.j ij-dgaz2ayn;yjei1 b1n 0v,s r 52jghtbulb 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.    $^{\circ} C$