What happens to the work done when a jar of orange juice is vigorouj k xrm h9ad5j+y-vr*l54dke4sly shaken?

When a hot object warms a cooler obj+wj2o-(q4t2wk bv 2fi fv, lynect, does temperature flow between them? Are the temperature cyl(vikj+w 2tf ,wq2 v2o-b4 nfhanges of the two objects equal?

(a) If two objects of different temperatures are )bk5qwh(b+q/ 4idpynplaced in contact, will heat naturally flow from the object with higher internal energy to the object with lower internal energy? (b) Is it possible for heat to flow even if the internal ener knhpbb)w qi4/(qd+y5 gies of the two objects are the same? Explain.

In warm regions where tropical plants grow buyh* vunr okir c4,ve tvbd17v+*pc( 4*t the temperature may drop below freezing a few times in the winter, the destruction of sensitive plants due to freezing can be reduced by watering them in t ckrdyvi7*cbet,vn4v+(* 1 po u *r4vhhe evening. Explain.

The specific heat of water is quiaj-y5fp5jl 7z+gp2-n n d-)qp xqr3a qte large. Explain why this fact makes water partiq 5-agqlqzy)n-ap - nj7rp 325jd fp+xcularly good for heating systems (that is, hot-water radiators).

Why does water in a metal canteen stay coolerh o-j+l3tltrcyyk9 95 if the cloth jacket surrounding the canteen 3klry j9+ty 9ocl-t5his kept moist?

Explain why burns caused by zbwz,2i 78kgln3 g9-c /2 wiousa(cxvsteam on the skin are often more severe than burns causedi2gvxl7 acc2kw o -3g,9us/wi bz8nz( by water at 100 $^{\circ} C$ .

Explain why water cools (its temperature drops) when it ea 53d3 9enzndjz koidlf6 )tm+,gp15 dvaporates, using the concepts of latent he 53ak)3t,fg+nmod i9p zz d6d1le5jd nat and internal energy.

Will potatoes cook faster if the water is boilirl4v a8n/wm2o ng faster?

Does an ordinary electric fan cool the air? Wh78jjc7i 4diuo m8r 3bfy or why not? If not, why use it?

Very high in the Earth’s atmov 6ttqv)l9; ajsphere, 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 themselves f (2 kid7zzpvrs:4 zi;n*ch1ywith snow. Why1 ii;rszv (c:2fh4kyp7z * ndz would they do that?

Why is wet sand at the5ro mry9rqvj7+t(qk1 beach cooler to walk on than dry sand?

If you hear that an object has “high heat content,” does that mean that its tovfscbwv*64 p8b-k-hb2atl / emperature is high? Explainkao/ws*p8bbl tv f c2bv-6-h4.

When hot-air furnaces are usr4 pmj ,n; 0eyxes01fged to heat a house, why is it important that there be a vent for air to return to the furnace? What happens if this vent is blocked by a bookn;s 0r10yjxgme4 fe, pcase?

Ceiling fans are sometimes reversible, so , 8:a5px.c9 guvere 1gk6opsqthat they drive the air down in one season and pull it up in another season. Which way should you set the fsp,9rx5k1 u.:e ao8ep vqcg6gan for summer? For winter?

Down sleeping bags and parkas are often sajdc3:*eu x g8 0lwbuf.z ce .b+*,ujspecified as so many inches or centimeters of loft, the actual thickwd*l. u ja+c.gjeu0:cs8f,3 uex bb* zness of the garment when it is fluffed up. Explain.

Microprocessor chips have a “heat sink” glued on top that looks li (a xqr3nt6s eg5i;vcak :r;e8ke a series of fins. Why is it shaped c it(v x83s6aran:gkeq5er;;like that?

Sea breezes are often encountered on sunny days at the shore of a large bod3ksz+ex3m et/ott *3ro .rfyxr (+g 3py of water. Explain in light of the fact that the temperature of the lar/3xg xoeze+3r.(ks t3t m3to+f*ry p nd rises more rapidly than that of the nearby water.

The floor of a house on a foundation under which thno;q; plupc:t9ne:i(e air can flow is often cooler than a floor that rests directly on the ground (such as a concrete slab foundation). Explain. nqp: ncoptle;u:9i(;

A 22 $^{\circ} C$ day is warm, while a swimming pool at $22\; ^{\circ}C$ feels cool. Why?

Explain why air temperature readings are always taeg;9cv ,4fsa mb3)le gken with the thermometer in tha e9f4eb), ; vlmcsg3ge shade.

A premature baby in an incubator can be dan5*f a:.fpz wb+-rpl orgerously cooled even when the air temperature in the incr. p5a :*fo-wfzlp +rbubator is warm. Explain.

Why is the liner of a thermos bottle silvered (Fig. 14–15) :hqxzho ecj*4h19 uno8i;+pa , and why does it have q+ine p :z coa 4*h98hjux;o1ha vacuum between its two walls?

Imagine you have a wall that+ *lzpc(8cvnh u;iwd4 is very well insulated — it has a very high thermal resist(+ vpw4;cc*uz n8dilhance, $R_1$ 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)ls .bl6,f0dazn kb ; aqz503kw ventilation 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) thal6 0fl3az0d,s.z bkk5qn; wbe 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 Sq/xv25js k9v/w16g7 dne sgk.kfn x5 uun absorbs more heat than a piece of shiny metal. Yet the wood feels less hot than the metal when you pick it up. Expld9 k/nfu6xkxgs 7 kj n/ 1ws52e5gqvv.ain.

The Earth cools off at night much more quickly when thea b1xpsj du315 weather is clear than when cloudxaj1u b 1s5p3dy. Why?

An “emergency blanket” is a thin shiny (metal coated) plastic foil. Expl3qd* .-x pk;t:s(l) :dk nsdsa8e nmxfain how it can help to keep an immobile person war:mn)sq k n(;d. sx:daxd* 8ks-elf3tpm.

Explain why cities situated by the ocean tendq8k -(6 2kicvnanp xb7 to have less extreme temperatures than inlann- n6p2akx8q 7kc(ibvd cities at the same latitude.

  How much heat (in joules) is required to raise the tempera ca9l+0gul4zzav(4 u zture of 30.0 kg of watv ull uz+zg(zaa494 c0er from 15 $^{\circ} C$ to 95 $^{\circ} C$ ?    $ \times10^{7 }\,J$

  To what temperature will 7700 J of heat rjex5t ezm5:o( 3i l4cs.it yh:aise 3.0 kg of water that is initially at 10.5mcsezx:yo4.jit:3 lht 5(ie 0 $^{\circ} C$ ?    $^{\circ} C$

  An average active person consumes about 2500 Cal r:vvd6h6*of a z:rlq6 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 the British system of units. da57hoh.y5 l sx:kb 7gOne Btu 55h77.x h:dlb k ayosgis defined as the heat needed to raise 1 lb of water by 1 F $^{\circ} $ . Show that
1Btu = 0.252kcal=1055J

  A water heater can generat42m9vdioan +ge $32,000\,kJ/h$ How much water can it heat from 15 $^{\circ} C$ to 50 $^{\circ} C$ per hour?    kg/h

  A small immersion heater is rated at 350 W. Estimate how long it willy pl5w;yxp0*uj( 5*kmfg2 aa c take to heat xf( ukj*;ya*m0 5ap2p5cl ygw a cup of soup (assume this is 250 mL of water) from 20$^{\circ} C$ to 60$^{\circ} C$ .    min

  How many kilocalories are gen*y l5xafx3-wf,i ku6 qrel8s3erated when the brakes are used to bring a 1200-kg car els 8*3xlx6 wykau-if q3,f5r to rest from a speed of $95\,km/h$ ?    kcal

  An automobile cooling system holds 16 L tc9v or(zyi, .jfp9/a of water. How much heat does it absorb if its temperature rises frvy9o9ir p/,t afcj(.zom 20$^{\circ}C $ to 90$^{\circ} C$?    $ \times10^{ 6}\,J$

  What is the specific heat of a metal substance if 13 xn;c paa+si.45 kJ of heat is needed to raise 5.1 kg of the met4 as+p i;xanc.al from 18.0$^{\circ}C $ to 31.5$^{\circ} C$ ?    $J/kg\cdot\,C^{\circ} $

  Samples of copper, aluminum, and water eyd1qy:h m7pv, *wnr2i xperience the same temperature rise when they absorb the same amount of heat. What is the ratio of their mwdq ,2n h vp:yymr7*1iasses? [Hint: See Table 14–1.]$m_{Cu}$ : $m_{Al}$ : $m_{H_2O}$ =    :    :   

  A 35-g glass thermometer reads 21nu6+ + ,ezr benanqq-:.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 o7tv; 3*as posxdkh +uh1) mt:lf 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 (mag)p5; (if*( aceb xctpss = $0.4\,kg$) 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 33 vsv ;z wyo6m.,r 0s90:atuylx0$^{\circ} C$ 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+dd2codol a7n6+pb6b .75 L of water initially at 8.0b67+cn2+a6opddl do b$^{\circ}C$? 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 from0sb(8;w b.efzdvqfv bq 74+h g 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 15.bsedw+8f ;4qf (g0b7zv bhvq.0$^{\circ}C $ , and its temperature after ignition is 53.5$^{\circ} C$ .    Cal

  When a 290-g piece of iron at 18ddqjd;mrs07 5 0$^{\circ} C$ 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 hammexg ei+at+0go/r 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 as the amount of heat nee)c 2nn5mb7l b:jh3g vw/8h dukded to raise itsvc j8hdn w:mb kh/ng)b2l73u 5 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 meltdi*.yrflo 9u- 16.50 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 a 45-m-highlilbl+6 8rh7mmc./2kn8vdqn building. If 65% of the thermal energy produced when it hits the ground is absorbed by tlm7 kr6.8/inqbllv m28nc+h dhe sphere, what is its temperature increase?    $C^{\circ}$

  During exercise, a person may giv x4zjcxyuo0y9n j .84we off 180 kcal of heat in 30 min by evaporation of w.4o y juc90wx8z4xjnyater from the 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 point is dropped into an insulated container ofsz4mo8 f z6r,j liquid nitrogen. How much nitrogen evaporates if it is at its boiling point of 77 K and has a latent heat of vapori6zzf,m s j8ro4zation 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 frevz bt9 kuy0m (.w,,l f2zafzl)ezer 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 kaegv*a 8.9i./7up1 a- 3u qmfp6p gv;b syqwdxg 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 consumes 8.0 L of water over the span of fourl*/y):jzm* pgr 5zwm s ;jwuc0 hours. Making the approximation that all ;lrwgzyu)wzjs 50/ m* pmjc*: 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 a1ec)u+povs7 ct 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 mercuxzrr;cnm c, /;ry 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 at 7rvk 1bzg(ja+$250\,m/s$ 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 piwf2 d4r9ic: x5q.nnmoving 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 rld t-vu6f:)f forensic investigator notes that the 8.2-g lead bullet that was stopped in a doorframe apparently melted completely on impact. Assuming the bullet was fu:) r-fdlf6 vtired 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 aluminumaj ghq4icy/ ffsm..*m3ow4 2bl (dh3 a 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 heat flow b+a31y7hqx3pd7ri xu8la0 nj x y conduction in Example 14–10, assuming that there are strong gusty winj8pyn0xu+ 3177qri hl 3da axxds and the external temperature is -5$^{\circ} C$   $ \times10^{4 }$ W

  (a) How much power is radiated by a tungsten sphers-;z znu /f1ybpu0j0ue (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 flows by conduction from the bloo(hc wop5./w gm cy7uv6lkg+-ud capillarieuwvkych.ug5l o-p(/+gc wm67s beneath the skin to the body’s surface area of $1.5\,m^2$ If the temperature difference is 0.50 $C^{\circ} $ , estimate the average distance of capillaries below the skin surface.    $ \times10^{-4 }$ m

  Two rooms, each a cube 4.0 m per side, share a 12-cm-thickst2iexaclzs:4 ln2 )/ brick wall. Because of a number of 100-W lightbulbs in os2z/:acnl xi 4t s)2lene 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 txh7v/ykf,ag)3bi 3l xhe 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 alumh x06jux;zh5l b 2oz(uinum rod of the same length and cross-sectional area are attached end to end (Fig. 14–18). The copper zljxo056bh2(; uzuhx 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 Earth rec8nv df9sb4r h94qa0x ceivesch490d9vr q x4ansf8b energy from the Sun.    $ \times10^{17 }$W
(b) Assume the Earth radiates an equal amount back into space (that is, the Earth is in equilibrium). Then, assuming the Earth is a perfect emitter ($e\,=\,1.0$) estimate its average surface temperature.    $^{\circ} C$

  A 100-W lightbulb generates 95 W of heat, which is dissipated through a tyrpmw3*v) h.glass bulb that has a radius of 3.0 cm and is 1.0 mm thick. What is the diff wp y*v.mtrh3)erence in temperature between the inner and outer surfaces of the glass?   $^{\circ}C $

  Suppose the insulating0f)m40i2t5y2k wv5okuyk k og 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 tot2ykwk 500)4okt iufk 5ogvmy2al 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, lpm7:lgv 3wqjw cna k5d +;4m3Fig. 14–20. (a) Show thmdn k3lpl5jg4; 7a:v qwcm3+wat the rate of heat flow through such a window by conduction is given by
$\frac{Q}{t}$ = $\frac{A(T_2-T_1)}{l_2/k_1+l_2/k_2+l_3/k_3}$,
where $k_1$,$k_2$ and $k_3$ are the thermal conductivities for glass, air, and glass, respectively. (b) Generalize this expression for any number of materials placed next to one another.

  Approximately how long should it take 11.0 kg of ice lk2+.jd + kteuk 3;osgat 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 liquidvpmv:a )5cc.ms(d z/n 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 containefutfl,19pjm(, v1g. nx57zds dr *gpa d in the world’s oceans, estimate the heat liberated when a cube of ocean water, 1 km pa pgf9d,xz1trs *u ,. (fnmjvg15 d7lon 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 wood with a masdwc7xva+ 9n gw/m1x e7ymb ;srawv,*4s of 1.05 kg. The block and imbedded bull ;b7a1ce+x* yxwr7vswmd,w/a9 n gv4 met together absorb all 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 spa-nl8os:d9 uj dedz sp(89iv2p ce by the Sun, assuming it to be a perfeplu8vz jed-d8sp (s:2ni9do9ct 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 perqqzs2hpt16 6p8xx 5 xuson 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 y85qnv:3:p 8 j jd/nxvdarc 8ecliff and falls a vertical height of 140 m before striking the ground. Estimate the temperature rise of the rock if 585endx8:r v: /cn3jydaq8j vp0% of the heat generated remains in the rock.    $C^{\circ} $

  A 2.3-kg lead ball is droppwq (r)p9qg .mm9* w9vn8pkgened into a 2.5-L insulated pail of water initially at gemq9 k8(pwn* .gn)wv9pqm9r 20.0$^{\circ} C$. 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 dok;m+tj7u2r lj7 fej 1lwn jacket 3.5 cm thick with total surface arej mr kllftjj1e7u 7+2;a $1.2\,m^2$ 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 averad);j*6 fivb emw/0cbwge 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 whichqie5rfl(.b ji. a 9;bt,wc +jd heat can be conducted from the interior of the body to the surface. Assume that the thickness of tissue is 4.0 cm, that the skin is9iq,.e5r djifbc.b(j; t +alw 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 thi75gq zgu9c txs4 b+q3bck (assume conductivity of air) and area94 +qxc3gu5stgbq7bz $410\,m^2$ 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 trave ;wvnc6p -9, neqxfm2jling 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 part60 74obmcvlulo +lni;y:l )yq (a) in Problem 58, take into account radiation from the leaf to calculate how muchbnui+l6: 4ly; )coqyll0ovm7 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 entersh ;mr06gt73k,t6n,kkssusbm the Earth’s atmosphere. If its initial temperature was bm ss6kk m3guhrnt;sk6,0 ,t7-125$^{\circ} C$ 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’s crus7uwjt v2e n4l.t 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 pfe d2-i jl3uj7eople hit a soft rubber ball at a wall until they are about to drop due to dehydration and exhaustion. Assume that thu-2j3 lif7 ejde ball hits the wall at a velocity of $22\,m/s$ and bounces back with a velocity of $12\,m/s$ and that the kinetic energy lost in the process heats the ball. What will be the temperature increase of the ball after one bounce? (The specific heat of rubber is about $1200\,J/kg\,$$\cdot\,C$)    $C^{\circ} $

What will be the final result w -hdu: )dcu4sghen 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 he08vu; pswci* yat by conduction and radiation at a rats cuwp8i v;*0ye 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 the xfzwqt0p2 y4 )50-gal (185-L) water heater. This suggests that the tank has emptied and refilled with water at w) p2 yzq4xf0troughly 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-m / o mkz3uh*x-t2m x.ntav-m*(eu b8sW 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.    $^{\circ} C$