What happens to the work done when a jar of orange juice is bu51lqab0( ku z0l- vttqhhx)8lo5 psfj3)l 2vigorously shaken?

When a hot object warms a cooler oc+9yu r8i hpr.bject, does temperature flow between them? Are the temperature iuchr 9r8+y .pchanges of the two objects equal?

(a) If two objects of different temperat0 -7n1et i 4eo50wxvov:mce ltures are placed in contact, will heat naturally flow from the object with higher internal energy to the object with lower internal energy? (b) Is it possible for heat to flow even if the internal energies of the two objects are the same? Exenteem i l ow050t-7:v 4v1xcoplain.

In warm regions where tropical plants grow but the temsycr 6e/7nd/-lw ulpze-6g)f perature may drop below freezing a few times in the winter, the destruction of sef6-un/d elzcy /plg ew7-s)6rnsitive plants due to freezing can be reduced by watering them in the evening. Explain.

The specific heat of water is quite large. Expzsj cmz)wr 6 qzydp41vd7e1d 9.) vb7jlain why this fact makes water particul db4jez v1ywdq)msz6 j.7zvc1 7)d9pr arly good for heating systems (that is, hot-water radiators).

Why does water in a metal canteen stay cooler if the cv3ovwcfb3 : jzru+d.br km/1*loth jacket surrounding the canteen is ke.1*b v+3ju wr/obkcm d3z:rvf pt moist?

Explain why burns caused by steam on th.es,s1; x cnwbcmep* 9e skin are often more severe than burns caused by waterbpcx*9sw,e.ecm; n 1 s at 100 $^{\circ} C$ .

Explain why water cools (its temperature drops) when it + 1sm5xcw3- ia.m juslxj(ji;pcxv35 evaporates, using the concepts of latent heat and internal energyi 1l. m+ijj(sjm x w3xc3pa-csu5xv5;.

Will potatoes cook faster if gt/ )qbi:gu de+4r*sbthe water is boiling faster?

Does an ordinary electric fan cool the air? Why or why not? Ifd.7a :crwwt6k-rp2td not, why use it?

Very high in the Earth’s atmosphere, the ten: skov6y;b 5fmperature can be 700 $^{\circ} C$ . Yet an animal there would freeze to death rather than roast. Explain.

Explorers on failed Arctiyrbvsc:dx m8g *83 v9j uyd)9.sb jag3c expeditions have survived by covering themselves with snow. b9v8mbg*3xsa). :d c 98yjv sy3grjudWhy would they do that?

Why is wet sand at the ben;ku5 kj kqj2+ rhz-7 d.wbu4vach cooler to walk on than dry sand?

If you hear that an obje b1ek h;8:,jcqg/wshlct has “high heat content,” does that mean that its temperature is higg8,e;qjsh: bkl1 wh/ ch? Explain.

When hot-air furnaces are use zbrypf9fhf7ag(5/5 ed to heat a house, why is it important that there be a vent for air to return to the furnace? What happens if tz/( 7 ryff5gfheab59phis vent is blocked by a bookcase?

Ceiling fans are som/1wv;ex*(ul wazocl/6 iduc(etimes reversible, so that they drive the air down in one season and pull it up in another season. Which way should you set the fan for summer? For; 1w6 uu*ivz (a le/dwlcxc(/o winter?

Down sleeping bags and parkas are often specified as soky 1zgus9g7 21zk 7kkv many inches or centimeters of loft, the actual thickness of the garment when it is fluffed up. Euz7gz kkk21 7k1g 9vsyxplain.

Microprocessor chips have a “heat sink” glued on top that looks lmde*ttz -; xvb(csh 4.ike a series of fins. Why is it shaped lik.-vm; s*x ezd4ttcb (he that?

Sea breezes are often encountered on sunny days at the shore im0g-5os0pj wvf* 8mz of a large body of water. Explain in light of the fact that the temperature of thjmf 0zp5mviw*0-g8o s e land rises more rapidly than that of the nearby water.

The floor of a house on jwmiuz o 0*5s -gx05xya foundation under which the air can flow is often cooler than x0 izj om0-5g*wxu5sya 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 readings are always taec+ 2gl 2mj4 u:0qv5f traqtp6ken with the thermometer in the sha+t2rt egmupcqj: 265 qla04f vde.

A premature baby in an incuba5iqh u 6ibqoma)4pe0; tor can be dangerously cooled even when the air temperature in the incubaqipoa6;u qmb04 h)ei5tor is warm. Explain.

Why is the liner of a thermos bottle silvered (Fig. 1vhd cum8-;9rv4–15), and why does it have a vacuum be8u9hvcrmv; -d tween its two walls?

Imagine you have a wall that is very5fjl5z)yoj a;5 bsqo exwe 23; well insulated — it has a very high thermal resijlje)zby w 5o3x f;;qao55se2stance, $R_1$ Now you place a window in the wall that has a relatively low R-value, $R_2$ What has happened to the overall R-value of the wall plus window, compared to $R_1$ and $R_2$ [Hint: The temperature difference across the wall is still the same everywhere.]

Heat loss occurs through windows by the following processes: (1) ventilation ar3 hdrxt n8lt/+ound 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 mechanism(s): conduction, convection, or radiation? (b) Heavy curtains reduce which8/r +ntx3l dth of these heat losses? Explain in detail.

A piece of wood lying in the Sun absorbs more heat than a piece of shiny mt0nl cvcm-sx9;j b2z9 etal. Yet the wood feels less hot than the metal when yt-slcb ;m 9nzc0j2 v9xou pick it up. Explain.

The Earth cools off at night much mogk(ksj ir1 z 4:7qo7sure quickly when the weather is clear than when cloudy. Wh1o i7 ks(qur4:jsz 7gky?

An “emergency blanket” is a thin shiny (metal coated) plastic fo3 1.a i-bsj76ftd; cfkn0vpeo il. Explain how it can help to keep an immobile0k3p;en fdoafjsi cv.tb61 7 - person warm.

Explain why cities situated by them iwpbh4p30 4o ocean tend to have less extreme temperatures than inland cities at the same latitud hwo34pip 40bme.

  How much heat (in joules) gzlz/eoqt:cy j3fg3 ij 4-i;-is required to raise the temperature of 30.0 kg of water fzj4 tqiyje;g-oig 3/3cl -: fzrom 15 $^{\circ} C$ to 95 $^{\circ} C$ ?    $ \times10^{7 }\,J$

  To what temperature will 7700 J of heat raise 3.0 kg of water that is initially ;xofcga- m427i1y+p8 zpupxe at 10.c41;px y fz+g-meax78p puo 2i0 $^{\circ} C$ ?    $^{\circ} C$

  An average active person consumes about yz4m6.u .gu i1tdew vse;0amhuz:dl 6/qu 7+ f2500 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) is a unit of h p .hvgwg *0h)4:jgylt4xg7s weat in the British system of units. One Btu is defy 0v.j4t4 g)wg7ghw ls: g*pxhined as the heat needed to raise 1 lb of water by 1 F $^{\circ} $ . Show that
1Btu = 0.252kcal=1055J

  A water heater can gek ;m+yj 10kk z567g/hkfqapr hnerate $32,000\,kJ/h$ 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 will take tobbc0p-b o3rt) heat a cup of soup (assume this is 250 mLcp0bb bo3tr) - 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-kg6rn ..vuqm6gmdc0s9 pq3oe h8 o03 dp.hr c8s9qgu ne6mvm6q .car to rest from a speed of $95\,km/h$ ?    kcal

  An automobile cooling system holds 16 L of wate25wipq ,k5. irsiqoz-* k .zfxr. How much heat does it absorb if its z5w i5ksk2qi*q i, r .fzop-x.temperature rises from 20$^{\circ}C $ to 90$^{\circ} C$?    $ \times10^{ 6}\,J$

  What is the specific heat of a metal substance if 135 kJ of heat is needed4rk 5(i ie5hedix; in;,-dbwo to raise 5.1 kg of the ;ei5ih-k, i ;d(n4odxwre 5 bimetal from 18.0$^{\circ}C $ to 31.5$^{\circ} C$ ?    $J/kg\cdot\,C^{\circ} $

  Samples of copper, aluminum, and * t 5eq. fv.8os.h ussp7zk8xxwjj5d.water experience the same temperature rise when they absorb the same amount of heat. What is the ratio of their masses? [Hint:so5v8 k*.xhs7pe. 8w z5djft.sjx q.u See Table 14–1.]$m_{Cu}$ : $m_{Al}$ : $m_{H_2O}$ =    :    :   

  A 35-g glass thermometpam (q7)83s 67owrt rtgqit(e er 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 d0:rqvnh9 bsby)i 53es h cg4,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 (mass n)t f3h+m yxqy967l;sg r urm8= $0.4\,kg$) 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 subhn9bo+h+ rxgg6)sn-u stance 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 to a boil 0.75 L of water incd3aii ue5l pk3 e(,vk:34ljbfu/ :jritially buai ,/ 4 lc5v(e3:dik3prue f3lkjj: 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 candy froow39lsp8dqg ):a*dnf m the following measurements. A 15-g sample3:9lpo*ansfwg 8dq d) 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 15.0$^{\circ}C $ , and its temperature after ignition is 53.5$^{\circ} C$ .    Cal

  When a 290-g piece of iron at ewkdf*lw-.5epzn ul.(0 jh*l180$^{\circ} C$ 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 spen -8faa w,hz,yed 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 defi 9:biom5kscog ; -iah7lt3d-ined as the amount of heat needed to raise its temperaturetc-ka5 iiosm 3 ;7-hbg l:d9oi 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 initially z+g z k z:ijpqu986pweu n25a7at 20$^{\circ} C$?    $ \times10^{6 }\,J$

  A 0.095-kg aluminium sphere is dropped from the roof of a 45-m-high0vmqdx x3 ;/cc building. If 65% of the thermal ec0c;qd/xxmv 3 nergy produced when it hits the ground is absorbed 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 evapora8ef w3.tsr: 7d cstjv,tion of water from the skin. How much wate ssdtwv f8tre3j :7.,cr 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 meltiw;bacy )38ua bng point is dropped into an insulated container of liquid nitrogen. How much nitrogen evaporates if it is at its bo;)acwa3uy8 bbiling 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 f84i h,g)mgy1i mg(q wirom the 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 230 kg contains 830 kg of water k:7din cpi. s;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 whb /cj -zp ,cn,)s zw/p4zg)baater over the span of four hours. Making the approximation that all of the cyclist’s en4ngh/ -/ z c,p)azc)w s,bjpzbergy 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*qcweck5+0o w.g nze 7 100$^{\circ} C$ 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 med1sx d5v6j *xt9akpk1 rcury 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 travelvkdtiqo/3fzy k572w ..: pedw ing 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 movfkbh2id ,944 sl qn6i5x ue*abing 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 8.2-g lead bulle-s gfw99p yp q7lq zo68loz:,w(lqco7t that was stopped in a doorframe appare s8o6o, zl (-lgw wqql :f7y7zcqopp99ntly melted completely on impact. Assuming the bullet was fired at room temperature (20$^{\circ} C$ ), what does the investigator calculate as the minimum muzzle velocity of the gun?    m/s

  One end of a 33-cm-long aluminum rod with a diameter of 2.0 cm is kepkp d//rk8bnk 9ppx78m t 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 con(oq q)jj2hp5:xf 0jnu duction in Example 14–10, assuming that there are qu 2 fhp0njj(5jo:x) qstrong gusty winds and the external temperature is -5$^{\circ} C$   $ \times10^{4 }$ W

  (a) How much power is radiated acs:ece9 yse n3 n7o,;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 heat flows by conduu o iaq6me67 /c6)g 5ddht3sfhction from the blood capillaries beneath the skin to the body’s surface area of6gt 75 fem u/6 co)qhds6ihad3 $1.5\,m^2$ 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 cubee26ehgj eoi 90 4.0 m per side, share a 12-cm-thick brick wall. Because of a number of 100-W lightbulbs in one room, the air is at 3g0j6eie29 oh e0$^{\circ} C$, 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 tak)op-is x ;2qf7pgp9toe the 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 aluminu7wmr(r)/ jqunm rod of the same length and cross-sectional area are attached eunqjm (r)7 wr/nd 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 th56tbx0r)t mmfi-x6 8 azyv 1vae rate at which the whole Earth receives enravx 1m)t i8t66y0zf ba- vm5xergy 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 di v. oglv l65+;inzi246nuehr /:g gpyhssipated through a glass bulb that has a radius of 3.0 cm and is 1.0 mm thick. What is the difference in temperatur hrihigo5n v:e. yvlg n+26z 4;u/g6lpe 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 4.31dw iugb) m2y,onsd2 0-in. layer of brick and an R-19 layer of insulation, as w g1 u,bdo mn2)sd3iy2shown 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 haswjuc(z5ut v8d4a3j4 ( otir z* two panes of glass separated by an air space, Fig. 14–20. (a) Show that the rate of heat flow through such a window by conduction is giv t(4ju(3i8vdw t5o4zjzar*c uen 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 a ds3ox p),/mgt6 u,gi 6lzdzz1t 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 0.9z o;qf8;ba/bir wx 1l5i cvc/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 the world’s oceans, lai7.9o ,dl ( kl khzl/:jlxk;estimate the heat liberated when a cube of ocean water, 1 k/ jlhad,:iklz ;. xlkkl(9l o7m 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 bk7lw,7.w*qp fh xu) thlock of wood with a mass of 1.05 kg. The block and imbedded bullet together absorb all the heat generated. After thermal equilibrium has been reached, the system has) *lxpf wqtwhk7,7u.h a temperature rise measured as 0.020 $C^{\circ} $. Estimate the entering speed of the bullet.    m/s

  (a) Find the total power radiated into52mr2e n1 qk:kcy1-tsr fz)fz space by the Sun, assuming it to be a perek5 kqs zf)2ztr1 -:r1m cn2yffect 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 pjeb /qs;r5bouhbh.3 , erson 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 -(f:v j2h: (vqn22v gtmksd nqoff 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 generated remdf :s:(nq2v-2 v t(km2hvqnjg ains in the rock.    $C^{\circ} $

  A 2.3-kg lead ball is dropped into a 2.5-L insulated pail of bbb 7la w,5x)twater initially at 20wxltab bb57 ,).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 utck f459a ruqtpv(0 /z9wg v3goose down jacket 3.5 cm thick with total surface areq pz(fw/9tu930ck ar5u tvg v4a $1.2\,m^2$ 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 fccy g.c3rah- yed lj9+6kh vt pt2--(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 which heat can be conducted from the interior 39 y/nmj+c vzgof the body to the surface. ny3z9cvm +gj /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 17.5 cm thick (axq ,n(xf iy9q hz5ij:j;bf::tssume conductivity of air) and aren9; jxbi(fjftiq:yqxz5 ::,ha $410\,m^2$ 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 tracp7s0,tohl3oljs6z. veling 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 into accouknt +hc 0 vxv9qn7ihv6abg3,.nt radiation from the leaf toiq+a v x9gn hvhk .03btc6v,n7 calculate how 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 Ekce4pb72 s.zo arth’s atmosphere. If its initial temperatu7 b.pzs2o4ck ere 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’s crust ehjpbae(vj f ig2-c +5d/z ,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 people hit a 79(zkfuy0ksvp/ gj;msoft rubber ball at a wall u/(0gzm9 sp 7kfk;yv ujntil they are about 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 fin4 ,e .nqd9lg wi.jm 43afsfc2hal result when equal masses of ice at 0$^{\circ} C$ and steam at 100$^{\circ}C $ are mixed together?

  In a cold environment, a persong(fpzm00 :zqn s8sy a. can lose heat by conduction and radiation at a rate of about 200 W. Estimate how long it would take for the :s0(p y fnzagz80ms .qbody 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 bja/o +7iq6ug50-gal (j+iub7 / o6agq185-L) water heater. This 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 )tx4ovw +fl1n8e d ,qv ,p,zousurface 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.    $^{\circ} C$