What happens to the work done cgs k 2k6w+z3hfls t1ikf,mc2 4;q s.awhen a jar of orange juice is vigorously shaken?

When a hot object warms a cooler object, does temperatd 4aspy z9h/nd;t x5bayr:0x :6qtln4ure flow between them? Are the temperature changes of th6a:bx0/n:zt94 y d4n rdqx pht5;y alse two objects equal?

(a) If two objects of different tq f.ot g,s4j0thv/s)memperatures are placed in contact, will heat naturally flow from the object with higher internal en/o 4 m fstgst),q0h.vjergy 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? Explain.

In warm regions where tropical plants grow but the temperature may drop bele 0m6:vcvq h/:vc.zxhqb6 b4 aow freezing a few times in the winter, the destruction of sensitive plants due to xmb0:c a cvh/h6qe:q4vv6.b zfreezing can be reduced by watering them in the evening. Explain.

The specific heat of water is quite large. Explain why this fact ma++9avc1k7.q flv cw ntkes water particularlt7+v vkcn .w qlc19+afy good for heating systems (that is, hot-water radiators).

Why does water in a metal canteen stay cooler if te6 f+-os1f ropnj0f7b he cloth jacket surrounding the cantf7-jb sf feop160o+nreen is kept moist?

Explain why burns caused by steam on the skin are often more severe than bur fn+)vp4)st92qfxve /rzh(fd4o:bfh xos x)8ns caused by wao+xv( z d tf brnfpvqxhh)294 :e)ss4xf)/ f8oter at 100 $^{\circ} C$ .

Explain why water cools (itfqrzr2- 2spb/ /e-,b pf ksi+gs temperature drops) when it evaporates, using the concepts of latent heat and inte/2 kiqf-+fbrb- rpgs, szep2/ rnal energy.

Will potatoes cook f2ab1dqrwg5 n, w2.v wdaster if the water is boiling faster?

Does an ordinary electric fan cool the air? Why or why not? If not, why euucdyd.+a*6dgw juwv ,)1p0- 6hnzruse it?

Very high in the Earth’s a 99xxbq3t cqb0x+f ,a ebd7)wftmosphere, the temperature 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 covering tt2 mce/9rcnof,0z 2a hrr(ak4hemselves with snow. Why would9(z,nct 2arh mo/4c2 0a krref they do that?

Why is wet sand at th qn q7u xrpn6(;c8vh;bgli z:s08n(vce beach cooler to walk on than dry sand?

If you hear that an object hai. p r)poydx,axz)u/ 1s “high heat content,” does that mean that its temperature i.uz1i )) yo/xrxpa ,pds high? Explain.

When hot-air furnaces are used to heat a house, why is it important that therejj ; hju(c (+aovtoc--b* )qkr be a vent for air to return to the furnace? What happens if this ven j*ctj-o )ubqo +ja( k-cr;(vht is blocked by a bookcase?

Ceiling fans are sometimes reversiboh cq:ib)2,hmle, so that they drive the air down in one season and pull it up ),q2i hohb:cmin another season. Which way should you set the fan for summer? For winter?

Down sleeping bags and parkas are kpag7s92kxao-t;:/iu +2mx hh qfp+ joften specified as so many inches or centimeters of loft, the actualtkk-h fpijhgmq+uxa;s22 pao/ +9 :x7 thickness of the garment when it is fluffed up. Explain.

Microprocessor chips have a “heat sink” glued on top that looks like a muh:54 *ac:kqs9 jrljseries of fins. Why cukq9:h:mr j5 j4sl*a is it shaped like that?

Sea breezes are often encountere fs6-e(rl+hfvwv96 gpd on sunny days at the shore of a large body of water. Explain in light of the fact that the temperature of the land rg (l9 6f6hrwvesp-v f+ises more rapidly than that of the nearby water.

The floor of a house 5z6oe5t/bm tjon a foundation under which the air can flow is often cooler than a floor that rests directly on the ground (such b t6j5/e zmto5as 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 temperaturjoiy;i) kza 5jke /w48e readings are always taken with the thermometer in th8y; jkie/5woak)4 z jie shade.

A premature baby in an incv1 toy wrw,mxecz6uw/+:+t)y x 5 *xlfubator can be dangerously cooled even when the air temp+xtte fl)y65 wumywxc,z/w*v+o1 : xrerature in the incubator is warm. Explain.

Why is the liner of a thermos bottle sil1 m 8ltd0yih2fvered (Fig. 14–15), and why does it have a vacuum between its two wallsi hft0l m82dy1?

Imagine you have a wall that is very well insulated — it has a very high thermaljt)4vnz /imy. . nxt8xtxx t/zi8.)n y4mn.jv resistance, $R_1$ 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 througc / iw8n:g5 3emkl7kidh windows by the following processes: (1) ventilation around edges; (2) through the frame, particularly if it is metal; (3) through the glass panes; and (4) radiation.g8nw: kk i5/cl eimd73 (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 absorbs more heat than a piecepdp n2e34mdvkp06894gyt c6cp zu oh+ of shiny metal. Yet the wood feels+pop4gc9c h 3tedd2640 npvyu8 k6pz m less hot than the metal when you pick it up. Explain.

The Earth cools off at night much more quickly when the a;t4-rutu u88;p1ey a2hz kroweather is clear than when cloudy. W 4 aer;yk82zpt u-;r1u u8hoathy?

An “emergency blanket” is a thin shiny (metal coyvnwq.- omtd:7hnqj(; r z;sk)le3.az6u r(q ated) plastic foil. Explain how it can help to keep an im.m nvu -. nhj:kyodrw sqz(aqrz(tq37e l;6 );mobile person warm.

Explain why cities situated by the ocean tend to have lu +eihe-y 9-gtpn2w4kess extreme temperatures than inland cities at the same latitudei-en9gep4 +h- wty2ku .

  How much heat (in joukx0,o .jm-rtxles) is required to raise the temperature of 30.0 kg of wate0mtxok- xj,r .r from 15 $^{\circ} C$ to 95 $^{\circ} C$ ?    $ \times10^{7 }\,J$

  To what temperature will 7700 J of hm+y 3)kr(l9dr(cvbw us 0q w7deat raise 3.0 kg of water that is initially at 10.0)u dwc0y7 bw md3vr9r(qsk l(+ $^{\circ} C$ ?    $^{\circ} C$

  An average active person cd n yhrep,6wtg44ys wnpf (o(f0(4;oionsumes 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)bm-w cx) n7o8r is a unit of heat in the British system of units. One Btu is defined as the heat needed to raise 1 lb nb7mc x)wo8-rof water by 1 F $^{\circ} $ . Show that
1Btu = 0.252kcal=1055J

  A water heater can generyn)do v+pqg+prj6 5a. ate $32,000\,kJ/h$ 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 longr /kr+vslf05d it will take to heat a cup of svrrd/ ksf 0+5loup (assume this is 250 mL of water) from 20$^{\circ} C$ to 60$^{\circ} C$ .    min

  How many kilocalories are generated when thlf0-exb+,x ms e brakes are used to bring a 1200-kg car to rest from a mb-+0xefs,xl speed of $95\,km/h$ ?    kcal

  An automobile cooling system holdsub;5 d5znis6 n 16 L of water. How much heat does it absorb if its temperaturebusi56n5 dn; z rises from 20$^{\circ}C $ to 90$^{\circ} C$?    $ \times10^{ 6}\,J$

  What is the specific heat of a 9gd.3eus;3lz p1jo ipmetal substance if 135 kJ of heat is needed to raise 5.1 kg of the metal from 18.s;jd3 el 3p9gozu.i1p0$^{\circ}C $ to 31.5$^{\circ} C$ ?    $J/kg\cdot\,C^{\circ} $

  Samples of copper, aluminum, and y-n4w;dfhjl ;c o*xrvp3 r 2m4water experience the same temperature rise when they absorb the same amount of heat. What is the ratio of t n3yrvr;4j*hcp2dlmf;- oxw 4heir masses? [Hint: See Table 14–1.]$m_{Cu}$ : $m_{Al}$ : $m_{H_2O}$ =    :    :   

  A 35-g glass thermome2 4xm e5rz5cjhter 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 when a 245-g block :o l41 4go 5vdkq as/6gatgs,xof 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 horseshoeknwdjd:+9x(o8l 7mmd ).awh ea1 ux 6b (mass = $0.4\,kg$) 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 heated to 33m1c/k wxguae5c sek(: 4w ea hk+12m6p0$^{\circ} C$ 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 0.75 L h-u c jy7g/7 o2m.r,sw0labzt hky7;c of water initiall hubmrwck 77/-t .cs7g2ylh azoyj,0;y 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 content of 75 g of candyiqap3-n +vq 5y from the following measurements. A 15-g sample of the candy is allowed to dry before puttq5q +av-3nypiing it in a bomb calorimeter. The aluminum bomb has a mass of 0.725 kg and is placed in 2.00 kg of water contained in an aluminum calorimeter cup of mass 0.624 kg. The initial temperature of the mixture is 15.0$^{\circ}C $ , and its temperature after ignition is 53.5$^{\circ} C$ .    Cal

  When a 290-g piece of wf et.(gf3k)d 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 has a speedn9(yea * 9niv/,c. x kdqcrm.b 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 o.s 5n0+o mdodhf heat needed to raise its teohs o.0d mn+5dmperature 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.f 0 ,+ kpvh;orf/n3j;yko8k qu50 kg of silver that is initially at 20$^{\circ} C$?    $ \times10^{6 }\,J$

  A 0.095-kg aluminium sphere is dropped from the roof of a0:dvt * suz3x:uwhh8y(n )x ri 45-m-high building. If 65% of the thermal energy pzxiuy0 sdtwv )3:hruxh* n:8( roduced when it hits the ground is absorbed by the sphere, what is its temperature increase?    $C^{\circ}$

  During exercise, a person may give off 180on v53mj(yj0k kcal of heat in 30 min by evaporation of water from the skin. How much watk jmn oy(jv350er 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 p kb d6k(m-a8ipoint is dropped into an insulated container of liquid nitrogen. How much nitrogen evaporates if it is at its boilinb6da p kkm8-(ig 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 freezn,y su,y9hn p(jl6fs7g3o) vzer at -8.5 $^{\circ} C$ and placed in a 95-g aluminum calorimeter filled with 310 g of water at room temperature of 20.0$^{\circ} C$. The final situation is observed to be all water at 17.0$^{\circ} C$. What was the mass of the ice cube?    $ \times10^{-3 }$ kg

  An iron boiler of mass 230 kg contaikowe.q( wy6 /a2aylkxf by24(ns 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 consumes 8.0 L of water4 /qq w/e,z wkz:wc-yw 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 effe:zzc/q/4wq- ,yw wkw iciency 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 1qs)8i5 qzbrwd uf(+8h00$^{\circ} C$ 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 is :.gwu9bek ox lo 2ggx5-0jbgvk:+za5$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 travelintl ;aketm-02i wu*-ppv) *io jg 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 athfqiutn 1 *cbe:)648oy-h ezg:gq;cm $6.4\,m/s$ 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 foreny+fml z17ziz/sic investigator notes that the 8.2-g lead bullet that was stopped in a doorframe apparently melted completely on impact. Assuming the l/yfm1 zz+z7i 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 w o7ss r*l/v0ytith a diameter 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 injf:abdu9d5 / n Example 14–10, assuming that there adu/:d bn5aj9fre strong gusty winds and the external temperature is -5$^{\circ} C$   $ \times10^{4 }$ W

  (a) How much power is radiatedgk5s87xe * w3e jfoj+t 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 h6z b0w7wgfz+heat flows by conduction from the blood capillaries beneath the skin to the body’s s0hz6z+wg bw f7urface 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 sid qaafp74a t j)qp)kf(+e, share a 12-cm-thick brick wall. Because of a number of 100-W lightbulbs in one tp 4a)7q)qfkf(jaa+ p 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 thfaxd5bak7 1x4e Sun to melt a block of ice at 0$^{\circ} C$ with a flat horizontal area $1.0\,m^2$ and thickness 1.0 cm? Assume that the Sun’s rays make an angle of 30$^{\circ} $ with the vertical and that the emissivity of ice is 0.050.    h

  A copper rod and an aluminum rod of the same length and cross-sectional w b5i9w::)jvp;v o 7h;ounbzearea are)ui; jeo9pon; b5v:7 bvw:h wz attached end to end (Fig. 14–18). The copper end is placed in a furnace maintained at a constant temperature of 250$^{\circ} C$. The aluminum end is placed in an ice bath held at constant temperature of 0.0$^{\circ} C$ . Calculate the temperature at the point where the two rods are joined.    $^{\circ} C$

  (a) Using the solar constant, estimate the rate at which the whole Ea g,:5e7,exu yxctbs7v rth receives energy from the7x7bg, st x:ev5c uy,e 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 di. ec7es8q)ie vssipated through a glass bulb the .e7vcs8ie)q at 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?   $^{\circ}C $

  Suppose the insulating qualities of the wall of a house come mainly from a 4.0-q sfmnqf+fz e63 ikk;c5z9.q 2in. 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 such9 ;fzs3.mi2q5q+zkfe6kn q fc 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 air space, Fig.2wzlfzu.ij a(eeo p84t3 /5e k 14–20. (a) Show that the rate of heat flow through such a window beeae8.j2o/wpliz zuk 4 (f35 ty 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 of iv2k8395jtbrs c; yvfl ce 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 0vpn,z) ja uqwgzx42t- 8r (yh0.20 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 thermal energy is contained in thet9f35 eqiwzzl / hy+m9 world’s oceans, estimate wz/tf93 li+m9h z5 eyqthe 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 this estimate.)    $ \times10^{ 15}\,J$

  A 15-g lead bullet is tested by firing it into a fixed block of woo 3wkou/dwg- yp 91,mwgi ;yq,sd with a mass of 1.05 kg. The block and imbedded bullet together absorb /;, m 9p-,oygd w3ywgsuqkw 1iall the heat generated. After thermal equilibrium has been reached, the system has a temperature rise measured as 0.020 $C^{\circ} $. Estimate the entering speed of the bullet.    m/s

  (a) Find the total power radiated into space by the Sun, assuming it l) blpl ir gg w8:r2+z2la0(+)/ulzuwjdc :k eto be a perfe l 2c/i :glwlrlu2zkd)8e++zlab r)w: (jp0ugct 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 n;++qmicf 6p d06rok zv7 gjov1vz0g (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 fa;;1*-lmskwv)x 8cmk 6aar l tfpkju24 lls a vertical height of 140 mmf-s2p) la6; ta1 u;m* lrvkjkx4kcw8 before 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 dropped ignh mh+5h5jw5wrj5 x-nto a 2.5-L insulated pail of water initially at 20.xw55g5r-jmhjhn5 wh+ 0$^{\circ} C$. If the final temperature of the water–lead combination is 28.0$^{\circ} C$, what was the initial temperature of the lead ball?    $^{\circ}C $

  A mountain climber wears a goose down jacket 3.5 cm th 6a3 x3kovmsn4ick with total surface area 346 maxnos3kv $1.2\,m^2$ 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 averu32o2ej*orc r j:ou8 xage metabolism rate of about $950\,kcal/h$ during a race. If the runner has a mass of 55 kg, estimate how much water she would lose to evaporation from the skin for a race that lasts 2.5 h.    kg

  Estimate the rate at whivdx ixj:t3zro6+x 7yd9 8 af9cch heat can be conducted from the interior of the body to the surface. Assume that the thickness of tissue is 4.0or7xvj6f3ix 8 zd9x+cy9a td: 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 (assume4 wfe8ckr+ z h/oi62wx conductivity of air) and are/ozi hrwf4c+x w28ke6a $410\,m^2$ 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 trap+.nylpmhmc;xh -e d36(v*oyk mn;; fveling 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, takexvx3 lzjpe:4) p myj-g-yt w(jrg/ r)5 into account radiation from the leaf to calculate how muchx(mt) jj5g4 g-l:e/3zxr- rvw)ypp yj 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 initial-,hp g7y1u m 3r+jnpfzg;g )aib/imf : temperatumb7n /3fgi;h,f y rpp:- i)+u1zagm jgre 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 Earthd3zr-a +gsvho l ni8(5-z1f eu’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 pe ,5hd /za9wmhdople hit a soft rubber ball at a wall until they are aboa9m,dh/z h d5wut to drop due to dehydration and exhaustion. Assume that the ball hits the wall at a velocity of $22\,m/s$ and bounces back with a velocity of $12\,m/s$ and that the kinetic energy lost in the process heats the ball. What will be the temperature increase of the ball after one bounce? (The specific heat of rubber is about $1200\,J/kg\,$$\cdot\,C$)    $C^{\circ} $

What will be the final result when equal masse0qah 9hctqg z)e q(:0wphc+x0s 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 co61g1:j u40u 5bj5c fe kfachsul/;asndva2r;nduction and radiation at a rate of about 200 W. Estimate how long it would take for the body temperatalb rkf105;a1c/j5;ands 6:cuu 4g 2ev fujshure 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,nhoc 7tn r(9 r(t6-r qmta.p,w there is “no hot water” left in the 50-gal (185-L) water heater. This suggests that the tank has emptied and refilled withtt9(-6 oqr.c7nwr rtp(,m a hn 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 gla; 3esn2wzrh1o ss surface 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.    $^{\circ} C$