What happens to the work done when a jar of orange juice is vigorousqyx9, )p.9rsqsf9v xu ly shaken?

When a hot object warms a cooler object, does temperature flow between thee6w lc3gizxo7 9dq*lxhte2 97m? Are the temperature chan9qi oxz7cl3xg9twlhe2*67d e ges of the two objects equal?

(a) If two objects of different temperatures are placed in contact, wz.6lfs:kccw /ill 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? Expla.w/6cf lc: kszin.

In warm regions where tropical plants grow but the temperature may drop belo ldm+*dbk4)b tw freezing a few times in the winter, the destruction of sensitive plants due to fred)lbtk4 m*b d+ezing can be reduced by watering them in the evening. Explain.

The specific heat of water is quite large. Explainqhecn1v10s5+,xpbm+m d d oe7 why this fact makes water particularly good for heating systems qchsv5 ,1dmm1 peeod 0 b7+n+x(that is, hot-water radiators).

Why does water in a metal canteen stay coole 91*tu-af ssfer if the cloth jacket surrounding the canteen ise9ff1s t -*sau kept moist?

Explain why burns caused by steam on the skin are often more severe than bur7 dc8gwvr4kq9vvo4 o6bho7 /q ns causev cv 7o46vkbo9w og7/ 48rhqqdd by water at 100 $^{\circ} C$ .

Explain why water cools (its rzb-a lx:2b,etemperature drops) when it evaporates, using the concepts of latent heat and : a,-2xze lbbrinternal energy.

Will potatoes cook faster if the water is boilingw a3m*ir j vdjp)6yx0: ;ov-qd faster?

Does an ordinary electric fan cool the air? Why ol2 c 58 (2zg z8tf,wudovdc;aeyz9hn3 r why not? If not, why use it?

Very high in the Earth’s atmosphere, the temperature can be 700 t( oush: ,7-j1hb*vlnfz .:kksh15r f-ubxj t$^{\circ} C$ . Yet an animal there would freeze to death rather than roast. Explain.

Explorers on failed Arctic expeditia.( jmt xd5z-x)y 0guldc3,nwons have survived by covering themselves with snow. Why woulwuyd3l-g( j) dcxxm50znt.,ad they do that?

Why is wet sand at the bea c/6 :i o9u-b4afnme4lpu*7m6 xevj llch cooler to walk on than dry sand?

If you hear that an object has “high heat content,” does that mean that itv52dne7 xh /vcjm 7l+vs temperatu7 cvx hl2me/d n57vvj+re is high? Explain.

When hot-air furnaces are used to heat a house, why is.g, l5nvsnsj6hl8 )dr it important that there be a vent for air to return to the furnace? What happens if this vent is blocked by a bookcn,d snvh8sl. lgrj6 )5ase?

Ceiling fans are sometimes reversible, so that they drive the 1; mj c,r,dgnf-smtz 8air down in one season and pull it up in another sesrj,nmc z1,8tdmgf; - ason. Which way should you set the fan for summer? For winter?

Down sleeping bags and parkas are often speci 0xw(zqp9j/osfied as so many inches or centimeters of loft, the actual thickness of the garment when it is fluffed up. Explain(/qoxj sz wp09.

Microprocessor chips have a “heabj 6i h;lzq75mo je(i3m6j:ua8 z)e ukt sink” glued on top that looks like a series of finseiuzm8q65j h3jbu7; aj:m zkl)(i o6e. Why is it shaped like that?

Sea breezes are often encountered on sunny days at tf :k-+eycw6 hwz cyyh/2yd-e 5xc(m/dhe shore of a large body of water. Explain in ligc cycef- 5:em+/2hwd y-z/y(6w k hdyxht of the fact that the temperature of the land rises more rapidly than that of the nearby water.

The floor of a house on a foundat*jl19,9 feyu(ckqei6iy,zohj n 07uv ion under which the air can flow is often cooler than a floor that rests directluj 6 hi k9ycyf(*l,q7,oeezj1n9 viu0y 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 u b7el2 w lyvc/-gqip02c, dv/readings are always taken with the thermometer in the shade2c 7cu-weby qv2 l/0plv g,id/.

A premature baby in an incubator can be dangerously cooled even when thec5 3iyrm zb)7gi.v7 wy ,9ze ijlh(ub, air temperature in the incubator is vyz)gm.5 (ezrc7iy9 i,b 7 h,luwi3jbwarm. Explain.

Why is the liner of a thermos botok+ hf0.lw538 p tdvyqtle silvered (Fig. 14–15), and why does it have a vacuum between its two wall.8td5 w3pf okqv0+ lhys?

Imagine you have a wall that is very well insulated — it has a iwy 356,hx fcc)zj v9pvery high thermal resistanc6fv3 5,h)zjwp9xyic c e, $R_1$ 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 fyn7h vhpt6l(nh h68i;ollowing processes: (1) ventilation around edges; (2) through the frame, particularly if it is metal; (3) through the glass panes; and (4) radiation. (a) For the firsh( n6 hhn ;vhlip78ty6t 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 piece of rwm7 ph m+,/osshiny metal. Yet the wood feels less hot than the metal when youpw7hros, mm +/ pick it up. Explain.

The Earth cools off at night much more quickly when the weather isp9chueb. )*juy u-n5l clear than when e5u9)cl.- p uujyh*b ncloudy. Why?

An “emergency blanket” is a thin shiny (metal coated) plastic foil. Explain how ndjg-x 39 ib5wit can help to keep an immobile person warm3 5 -dxgnijw9b.

Explain why cities situated by the ocean tend to have less ze6;3f q7cp8ul vhzh 0extreme temperatures than inland p8uv3zfh 0ec6q7l;zhcities at the same latitude.

  How much heat (in joules) is required to raise th /3tsvi3rho 3ziih6,ne temperature of 30.0 kg of water frt 333h/nii,r hzi v6osom 15 $^{\circ} C$ to 95 $^{\circ} C$ ?    $ \times10^{7 }\,J$

  To what temperature wim sx69/dji7c fll 7700 J of heat raise 3.0 kg of water that is initially at 10sijfc76m /xd9 .0 $^{\circ} C$ ?    $^{\circ} C$

  An average active person consumes about 2500 Cafg q,eaz(y :dnl*ev ;*l a day.
(a) What is this in joules?   $ \times10^{7 }\,J$
(b) What is this in kilowatt-hours?    kWh
(c) Your power company charges about a dime per kilowatt-hour. How much would your energy cost per day if you bought it from the power company? Could you feed yourself on this much money per day?    dollars per day

A British thermal unit (Btu) is a unit of heat in th: pl5t5*lv vpi;6qrtle British system of units. One Btu is defined :pq*vlil;5t 5tv rl6pas the heat needed to raise 1 lb of water by 1 F $^{\circ} $ . Show that
1Btu = 0.252kcal=1055J

  A water heater can gene3 rjyz3l(u0p urate $32,000\,kJ/h$ 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 howl(rrf .5av5lb long it will take to heabrravf5 l5.(lt a cup of soup (assume this is 250 mL of water) from 20$^{\circ} C$ to 60$^{\circ} C$ .    min

  How many kilocalories are generated when the brakes are used to bring a 1200-b 9*n,m,cneqg kg c9q,cnmb eg *n,ar to rest from a speed of $95\,km/h$ ?    kcal

  An automobile cooling systeec6 qfc+1 qbjf4xw(oe6 ;bis 6m holds 16 L of water. How much heat does it absorb if its temxicb(+f6fqc6b4 1jsqe 6 eo ;wperature rises from 20$^{\circ}C $ to 90$^{\circ} C$?    $ \times10^{ 6}\,J$

  What is the specific heat fz m 4 )twkuc-;jj vaf,vk:u**of a metal substance if 135 kJ of heat is needed to raise 5.1 kg of the metal from uuz fwk4m*kf;c,tv* :)j-vaj 18.0$^{\circ}C $ to 31.5$^{\circ} C$ ?    $J/kg\cdot\,C^{\circ} $

  Samples of copper, aluminum, and water experience tkf3y r3/ d6ion8jvnn2he same temperature rise when they absorb the same amount of heat.3r ny2vkio83 njd/6f n What is the ratio of their masses? [Hint: See Table 14–1.]$m_{Cu}$ : $m_{Al}$ : $m_{H_2O}$ =    :    :   

  A 35-g glass thermometer r07)kk(ha/5ordn y jtpi1) bdreads 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 :-qh//mri6 ) 4uvy hrkj ho8zyiomz ,+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 (majwiap, n:i5/0jko uh( ss = $0.4\,kg$) 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 subsw y,)ydao 0i-ktance is heated to 330$^{\circ} C$ and then plunged into a 105-g aluminum calorimeter cup containing 165 g of water and a 17-g glass thermometer at 12.5$^{\circ} C$ . The final temperature is 35.0$^{\circ} C$ . What is the specific heat of the substance? (Assume no water boils away.)    $J/kg \cdot C^{\circ} $

  How long does it take a 750-W coffeepot to bring t5zq1 w6ajzr c2o a boil 0.75 L of water initially a 21rz5wqjzc 6at 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 from the follo+ + pxjs)dm+wh k1b)wewing 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 calorim1p+ebmjxk+ h+)) w wdseter 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 otn c, utfh9* q8p49miuf 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 b: uly8vrx 0 ft-hyo +/l;5yxza hammer 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 jy i(xbuwcu,w1+ m4a9o,xyf0 object is defined as the amount of heat needed to raise itx(wa 0juf,b4 +w ,c91m yuioyxs temperature by 1 $C^{\circ} $ . Thus, to raise the temperature by $\Delta\,T$ requires heat Q given by
$Q\,=\,C\,\Delta T$
(a) Write the heat capacity C in terms of the specific heat, c, of the material.
(b) What is the heat capacity of 1.0 kg of water?    $ \times10^{3 }\,J/C^{\circ}$
(c) Of 25 kg of water?   $ \times10^{ 5}\,J/C^{\circ}$

  How much heat is needed to melt 16.50 kg ywnttabnh5 t*ki/ - w7d;9u5wof silver that is initially at 20$^{\circ} C$?    $ \times10^{6 }\,J$

  A 0.095-kg aluminium spherem7yl(,xl794a6,w odminw m uy is dropped 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 4myalxw,l on7 7i6(duw,9 mmy its temperature increase?    $C^{\circ}$

  During exercise, a person may give off 180 kcal of heat in 30 min by nw 7rl,/khj5r evaporation of water from t7,kr5w/lr nhjhe skin. How much water 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 poiwab. .ahaf 0-6n0wv +yoa fas+nt is dropped into an insulated container of liquid nitrogen. How much nitrogen evaporates if it is at its boiling point of 77 K and has a latent hean-a+v0swab aoyaf6ha..fw +0t 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 t.s3eab,)fob mhe freezer 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 *qfgy11y p 6;umix ulw /nf88o230 kg contains 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 coa*bc8 0m 9f401rx/fiay+ougsq s3qapnsumes 8.0 L of water over the span of four hours. Making t4 sc89q30puqas1/ m+aa ygrxfb0oif*he 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 is not far off.)    kcal

  What mass of steam at 10 (5mxswe.mx)u k dc/x,0$^{\circ} C$ 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 pdr v/7tm- l9kmlpd8dy;k; +fmercury 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 traveling aor +biz*z: z-xt $250\,m/s$ 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-skaterv5 pudjg aa (s/)7 ,xb6d5)k6t5uvyyg2w zvba moving 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 investigatoi/0zia14s v h* l9ydner notes that the 8.2-g lead bullet that was stopped in a doorframe apparently melted completelye9yd/nsa lviz 0 41*hi 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-l5d mvqi)e :lfrrsfs+8 ; 5-cgnong aluminum rod with 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 -6uuu ecn-f rr zk:lq-4+*dsmheat flow by conduction in Example 14–10, assuming that there are srm*+q-4 eufl-k- n6 cz sdru:utrong gusty winds and the external temperature is -5$^{\circ} C$   $ \times10^{4 }$ W

  (a) How much power is radiated by a tungspy99r .-tzj grddj).d , hh4evten sphere (emissivity $e\,=\,0.35$) of radius 22 cm at a temperature of 25$^{\circ} C$ ?    W
(b) If the sphere is enclosed in a room whose walls are kept at -5$^{\circ} C$ what is the net flow rate of energy out of the sphere?    W

  Heat conduction to skin. Suppose 200 W of heat 7z/grqf g7 q3eflows by conduction from the blood capillaries beneath theqg 7 er7f/q3gz 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-thick bricj nxtthy8,( fo+n-lqs 1yv,y2k wall. Because of a number of 100-W lightbultyj , f(o1+qt y-ylnh2v,sn8x bs in one room, the air is at 30$^{\circ} C$, while in the other room it is at 10$^{\circ}C $. How many of the 100-W bulbs are needed to maintain the temperature difference across the wall?    bulbs

  How long does it take the Sun to melt a block of ice a2hq bz;f oy5ghyh9fz( 5p 55nkt 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 th .h md8979jd1mmpwklr sp2rc/e 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 temper2s9 kd p.97mdwh1p r8jml/r mcature 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 at3/(tq )qn ctol3ddjy . which the whole Earth receives energy fro ctlqy d/.n)to(33qjdm 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 gla 9k5u:gfdtfof wga1; cx34lh2ss 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 1 hg:4f 2acf3kl;d towx9f ug5outer surfaces of the glass?   $^{\circ}C $

  Suppose the insulating qualities of the wallbz u64 an j52tz6nces+gpn78g of a house come mainly from a 4.0-in. la8 nupj2a56z4gzgsb7 entn 6+ cyer of brick and an R-19 layer of insulation, as shown in Fig. 14–19. What is the total rate of heat loss through such a wall, if its total area is $240ft^2$ and the temperature difference across it is 12 $F^{\circ} $?    Btu/h

A double-glazed window has two panes of glass separated by ann 4m(x: se9mgh air space, Fig. 14–20. (a) Show that the rate of heat flow through such a window49e(mm hs:xn g 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 shouldd+n59)pt1cr ri jdu l3 it take 11.0 kg of ice at 0$^{\circ}C $ to melt when it is placed in a carefully sealed Styrofoam ice chest of dimensions $25\,cm\times\,35\,cm\times\,55\,cm$ whose walls are 1.5 cm thick? Assume that the conductivity of Styrofoam is double that of air and that the outside temperature is 32$^{\circ} C$.    $ \times10^{4 }$s

  A soft-drink can contains about 0.20 kg 1g f+1enrdzyw xe/g+) 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 the6:6v*/oee:x )rmlld rg9btyygak -w bq4/kf4 world’s oceans, estimate the heat libere 4*fw4yl / robd:gkg6elyx9qk -6tvbm/a) r:ated 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 wo 4) agw+as2t laww9j9dod with a mass of 1.05 kg. The block and imbedded bullet together absorb all the heat generated. After thermal equilibrium has been reachea2+awltsw 99gda j) w4d, 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, assumi*q8xfzym+ o:1 bf1ui-obrl k2ng it to be a perfect e q2:lubr1f f*mxi1 8yzb ook-+mitter at $T\,=\,5500K$ The Sun’s radius is $7.0 \times10^{ 8}\,m$    $ \times10^{ 26}\,W$
(b) From this, determine the power per unit area arriving at the Earth, $1.5 \times10^{ 11}\,m$ away (Fig. 14–21).    $ \times10^{ 3}\,W/m^2$

  During light activity, a 70-kg person may genek4uj r1vr p 0 y0)b*d6bw.lkfzrate $200kcal/h$ 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/mn1vbz chk; :u/ o44j ec2noc top of a cliff and falls a vertical height of 140 m before striking thu :hnmvkj//1;b4e2cz4ncco o e 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 into a 2.5-L *j 31(qx z iyz69v elnnso2yk.insulated pail of water initially at ( ns 3znz.2lxkij*9e6 oyy1 vq20.0$^{\circ} C$. 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 thick with total surface are knm va2t8+1bea 1m +vae tn8bk2$1.2\,m^2$ 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 8yjzbhlh*(fzb :. 0eg 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 whibo j2.f /zvdq2 bf18smch heat can be conducted from the interior of the body to the sofbbzqm fd1 2.sv/28 jurface. 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 walls 17.esmgqmo2,tg /- m6h-9lk y)ui5 cm thick (assume conductivity of air) and i2ggm mt 6lu 9mh,e-y-/sk)oqarea $410\,m^2$ 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 travelingdxbr5aoj9t 3;x y5ov3j9 fd* d 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) iffa2gab8 (iww) 3-e xsn Problem 58, take into account radiation from the leaf to calculate (bf w38) ge -2sfawxaihow much water must be transpired (evaporated) by the leaf per hour to maintain a temperature of 35$^{\circ} C$.    g/h

  An iron meteorite melts when it enters the Earth’s atmosphe hf;teyy +qm8o1jp*u9re. If its initial temperature was -125 q 8*ouyey+mt;h9f1p j$^{\circ} C$ outside of Earth’s atmosphere, calculate the minimum velocity the meteorite must have had before it entered Earth’s atmosphere.    m/s

  The temperature within the Earth’s crust increases aboutg0brn-vf( uf , 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), uhv, /ec8quc9 gx67kctwo people hit a soft rubber ball at a wall until they are about to drop due to dehydration and exhaustion. Assume that the ball hits the9hck,ex7u c/q8 6uvc g 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 masses , gn2c*nvyg 1mof ice at 0$^{\circ} C$ and steam at 100$^{\circ}C $ are mixed together?

  In a cold environment, a +u-m;mpo w ra.-1b+t tb3t ishperson can lose heat by conduction and radiation at a rate of hwt -opi s+1tb+mambr-u.; t 3about 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, theref(,k cok; /pwn,z*d8jj6s j;n6evcqp is “no hot water” left in the 50-gal (185-L) water heater. Tjo6,;es j f6;nc jwk*vp,z/ q(kpcd8nhis suggests that 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 surface of a 60-W lightbulb is 65*z i5l ouaz1yhjacu 2;1hx5h e* j5f-f$^{\circ} C$ 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.    $^{\circ} C$