What happens to the work done when a jar of orange juiyx 23bf5 v qfo-/o,seuz y*bd-ce is vigorously shaken?

When a hot object warms a cooler object, does temperature flow betwehv0 6k0 wsagym(no.h/by7if. en them? Are the temperature changesg6/ y .n.(b0ywfmoa7svk hih0 of the two objects equal?

(a) If two objects of different temperatures are placed c f6zne kbo/z961 cr /m5ddu8a./wr toin contact, will heat naturally flow from the object with higher internal energy tt8ewnz9/ma5oo.c b /6r6rd1duc f z/ko 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 te s4/ vdtomtjk5t(06dpvv(t r6 mperature may drop below freezing a few times in the winter, the destruction of sensitive plants due to freezing can be reduced dr(p (5/ksm t06tvvvot dj64tby watering them in the evening. Explain.

The specific heat of water is quite large. Explain why this fact makes wam3j z.u* 9jusg.f- igater particularly good for heatin.jsu.m3g- aufi j*9g zg systems (that is, hot-water radiators).

Why does water in a m3v:rem clm-q /4f+bt5eye1 et,0vtet etal canteen stay cooler if the cloth jacket surrounding the canteen i 4vem c 1e/-etrm:eytfeqv0b+tt 53l, s kept moist?

Explain why burns caused by steam on the skin are often more severe i0qq ku ( 9iqsn2p,p.ethan burns caused by wate se9 .p,(ip 0qqukqi2nr at 100 $^{\circ} C$ .

Explain why water cools (its temperature drops) when it evaporates, using the colx9o8ej*tw+n1 sobw. :ej8dd ncepts of latent heat an8ndd:weo lsoe.jt9 w1*x+b 8j d internal energy.

Will potatoes cook faster if the water is boiling fa8og n1swas-olox61f y8/mh; o ster?

Does an ordinary electric fan cool the air? Why or why not? If not, w6 uzt2pgquytl b.y:*2rdo. 9nso,5w zhy use it?

Very high in the Earth’s atmosphere, the temperat7w,m7z,zxu/.-fgjfbcoeg q. ure can be 700 $^{\circ} C$ . Yet an animal there would freeze to death rather than roast. Explain.

Explorers on failed Arctic expeditions have survived b- ij::bujhh6ms;rcghe94 c 4i y covering themselves with snow. Why would they do thathh-g 49isu i4j :rhj;6 :bccem?

Why is wet sand at the beach cooler tigsun z-lj p/2wu.2itq5qn;* o walk on than dry sand?

If you hear that an object has “high heat content,” does that me k-11zlmbdef(an that its temperature is high? Expl1(dkl1fz -mbe ain.

When hot-air furnaces are used to heat a house, why is it imp8( 8kd;fao.b5ic;f* emrao frortant that there be a vent for air to return to the furnace? What happens if this vent is blocked by8af .; r; ofa5 e*cibkrfo8md( a bookcase?

Ceiling fans are sometimes reversible, so that they drive tz3ddf0g gg,t;he air down in one season and pull idg;gf3, 0dgtz t up in another season. Which way should you set the fan for summer? For winter?

Down sleeping bags and parkas are often specified as so maz4b:5jda buby,9wmq3 ,2h ft rny inches or centimeters of loft, the actual thickn5z,dtb: bwq fbaur 3jy4m2,9hess of the garment when it is fluffed up. Explain.

Microprocessor chips habg/ siw895hms e+:joive a “heat sink” glued on top that looks like a series of fins. Why is it58i9:g ssb eh+/jm owi shaped like that?

Sea breezes are often encountered on sunny daydj7b01yn t5 qr9wc j3gs at the shore of a large body of water. Explain in light of the fact that the tempy3 qjrg0wdcn7 15bt9 jerature of the land rises more rapidly than that of the nearby water.

The floor of a house on a foundation under which the air can flem,8yjug2 mg3 ow is often cooler than a floor that rests directly on the grouym 2m8gue, gj3nd (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 taken with the thermometer in k/+wdr2 8txe qthe shaxkrw8eq+ / t2dde.

A premature baby in an incubator c x-v9 2kp3:3duv+a(yrada qb can be dangerously cooled even when the air temperature in the incubator is warm. Exvk d -32x(ray93 adcv:q+baupplain.

Why is the liner of a thermos bottlvd 0h/i6zoma0n 1sj57eiwh /n e silvered (Fig. 14–15), and why does it have a vacmnwa j d1i0o iz 5/0/hvhsn6e7uum between its two walls?

Imagine you have a wall that is very wer35mk 8dw ,vbkll insulated — it has a very high thermal resist8 rd5kk ,m3vwbance, $R_1$ 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) ventilation99jbd/g e5.zd vxr :un around edges; (2) through the frame, particularly if it is metal; (3) through the glass panes; and (4) radiation.9gjdvbx:5z/e 9d unr. (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 thaax7 lqglm7b +w,y.c(kn a piece of shiny metal. Yet the wood feels less hot than the metal when yoqm a,.gw7x7 +llykb (cu pick it up. Explain.

The Earth cools off at night much ;qmn;rotz 3j1kpn )r9 more quickly when the weather is clear than when cloudk;13znrnqp 9 ormt)j ;y. Why?

An “emergency blankety6 yg ,p/z9r u4qep)ue8l) prz” is a thin shiny (metal coated) plastic foil. Explain how it can help to keep an immob)z)e6,u9g/rppu qylep 8y 4zr ile person warm.

Explain why cities s/yuql shxu2c :o58874sbbnqr ituated by the ocean tend to have less extreme temperatures than inland cities at the same lati b87 /ou2q qns yrcxsulbh:485tude.

  How much heat (in joules) is required to raise the temf ub+0k-sufx5 perature of 30.0 kg of water fro5 -+uuffxs b0km 15 $^{\circ} C$ to 95 $^{\circ} C$ ?    $ \times10^{7 }\,J$

  To what temperature wi qh . ;gt:/k dkhhpg5ifze:u/,ll 7700 J of heat raise 3.0 kg of water that is initially at 1/z h e k5p/td:gk hfqu;:i,h.g0.0 $^{\circ} C$ ?    $^{\circ} C$

  An average active person consumes about 2500 Cab g3/ae* 6 odmpaha3-sl 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 sysu4u3 rviw87y(-t mviptem of units. One Btu is defined as the he wu-iry8p(u 4m7ti3vv at needed to raise 1 lb of water by 1 F $^{\circ} $ . Show that
1Btu = 0.252kcal=1055J

  A water heater can gen15 rqaw ftq(7jerate $32,000\,kJ/h$ How much water can it heat from 15 $^{\circ} C$ to 50 $^{\circ} C$ per hour?    kg/h

  A small immersion heater isxq ksm 9cm* 1;b+owj:2td 2dfc rated at 350 W. Estimate how long it will take to heat a cup of soup (assummmt2skjwb2:*od dccx ;+1f9q e 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 briny-knkt/ r.e i(*1y to2;bay yig a 1200-kg car to resy*tk 1/k. ya(no;y 2bi-eytr it from a speed of $95\,km/h$ ?    kcal

  An automobile cooling system holds 16 Lcal; istx4 k: w6hg(0z of water. How much heat does it absorb if its temperat 4sglk6hx :; c(wzta0iure 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 needed e.)vgonf9 x rpa e)a gac6fwk,wq4)3:to raise 5.1 kg of the metqgfwna . o6 prg e9)c,)ex)3a k:v4fawal from 18.0$^{\circ}C $ to 31.5$^{\circ} C$ ?    $J/kg\cdot\,C^{\circ} $

  Samples of copper, al, y6y6ubil* c psor5a9uminum, and water experience the same temperature rise when they absorb the same amount of heat. What is the ratio of 9ui b5rocp6yly6 ,s a*their masses? [Hint: See Table 14–1.]$m_{Cu}$ : $m_{Al}$ : $m_{H_2O}$ =    :    :   

  A 35-g glass thermometer reads3j6nh dit6mayv7/z1 p 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 a74qp;mn9uk(yc0t2 w-g urp xx 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 (m 3jd0j-j(40 tw4)trkumzahjz5,n u + h2fucxrass = $0.4\,kg$) 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 substancu;ickcqj9+h kt,iaxkb n8+ ;0e 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 u-r05w-;male x.v tm.bi(ngz 750-W coffeepot to bring to a boil 0.75 L of water initially a5i .gurme0b-l(-t xnazmv; w.t 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 o y w*3sy75 rlt2 rr9gs:xy9npfrom the following measurements. A 15-g sample of the candy is allowed to dry before putting it in a bomb calorimeter. The aluminum bomb hasrry:xyw r * ny923psot5l 97sg 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 180ar,)sb3t bkq92c rlu-$^{\circ} C$ 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 speed o4uv k -gfbcg-wtf13/,a 8ufolf $6.5\,m/s$ 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 th44 p7k8ps+putap) zo he amount of heat needed to ra+so p7 hp84pauz )tk4pise its 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 of silv db4;+mk4dy/ io tsle+er that is initially at 20$^{\circ} C$?    $ \times10^{6 }\,J$

  A 0.095-kg aluminium sphere is dropped from the roofplv,fqgc8b8ny s;6 pl 3-me4h of a 45-m-high building. If 65% of the thermal energy produced when it hits the ground is absorbed by the sphe fvl,hcgp4l8qn8b ;6p y 3es-mre, what is its temperature increase?    $C^{\circ}$

  During exercise, a pers2/y qrcccre1c2 --yzfon may give off 180 kcal of heat in 30 min by evaporation of water from the skin. How much wr2r /cqzy -yccf 1-ce2ater 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 insula 6od *ikcywgdr 83d 9c:dmv:z(g4i1b tted container of liquid nmb3y ci1d8gg r(dvwd9t4oz*i6ck: d :itrogen. How much nitrogen evaporates if it is at its boiling 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 freezer at -8.5hcn)2kznr 5t:7 4taijel d/f 4 $^{\circ} C$ 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 knpc+, ypz.i- gt0k4b8+ub5usiz ppl n)rd37 pg 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)93m/cp m(ypibyw4yv consumes 8.0 L of water over the span of four hours. Making the approximation that all of the cyclist’s energy goes into evaporating this water as sweat, how much energy in kcal did the rider use during the ride? (Since the efficiency of the rider is only about 20%, most of the energy consumed doy )49viym(p b/pcy 3mwes go to heat, so our approximation is not far off.)    kcal

  What mass of steam at 1 e *vz927y,et/+fznkzfhfh:b l6 8ira00$^{\circ} C$ 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 h cmw yx jl02*s7m+sw r806wsumercury 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 travelingltr7 :(a(k rxjp*hmx) 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 movinbef+ir( hxuv k +dtrm6r-w0wd b 7hh+1s4/)vag 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 bullet tha,vud1; )bjmw ct was stopped in a doorfrbwd ) j;m1,uvcame apparently melted completely on impact. Assuming the bullet was fired at room temperature (20$^{\circ} C$ ), what does the investigator calculate as the minimum muzzle velocity of the gun?    m/s

  One end of a 33-cm-long aluminum rod wit:9)fqtjy )c1wtj f k9::slsbqh 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 in Example 1u8v lk; wnm04w4–10, assuming that there are strong gusty winds and thlm8w;4vk 0nuwe external temperature is -5$^{\circ} C$   $ \times10^{4 }$ W

  (a) How much power is radiated by a tungst:ponf3 5x t f0*sxkm2ten 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 heatkerj0:vdzpdx 2sfi: v7llf4 r0x .2d: flows by conduction from the blood s: v 2 xez20kx:lprf dj.fl7i0vr:dd 4capillaries 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-thick memu+ wwlw,9a(qoqt6 wf3+8tzy3q m.t/o7sl brick wall. Because of a number of 100-W lightbulbs in ww y,owmm(au98.+sf/t+3o7e3 tz6qll w qt m qone 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 that(4eez4x pv zh*h,n* e 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 leg 9 t sunxk rsn9rf+3eq)q9c0,ngth and cross-sectional area are attached end to end (Fig. 14–18). The copper end is placed in a furnace maintained at a constant temperatur9s3q)0t,9srck 9un+ x gqenfre 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, e*/)vu geifsx7k3-vm-qcc n7 jstimate the rate at which the whole Earth receives energy from the Sun. qx- i/m)eusj v v*k3cnfc-7g7    $ \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 dissipatie1-kcd i3fl (5tr*cjed through a glass bulb that has a radius of 3.0 cm and is 1.0 m* l1jrik- cifdt3 5ec(m 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 9wph ,f ) efxa*6x w2tvz0j3jfa 4.0-in. layer of brick and an R-19 layer of insulation, as shown 0 f,evhw9wfz tp3fjx2j6 )*xain 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 windowyg ykwc3u*j2 tijlia5)i /i32 has 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 conduc2j)w*ii t/2uak3y 3g c l5yjiition 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 at 0bs:0m roky/ 9o$^{\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 lg3w a :4 .fi.rb5bhdpdiquid 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 i:3mf3 fe*do6zv 6v8wgq h/glen the world’s oceans, estimate the heat liberated when a cube of ocean water, 1 km on each side, is cooled by 1 K. (Approximate the ocean water6f/wv3e3 g8f lgo q*:hzmed6v as pure water for this estimate.)    $ \times10^{ 15}\,J$

  A 15-g lead bullet is tested by firing it into a 54+lb(dp h4rju6ph s rfixed block 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 a temperature rise measured as 0.020dbhl4h6p+ruj(r5 s 4p $C^{\circ} $. Estimate the entering speed of the bullet.    m/s

  (a) Find the total power radiated into space by the Sun, assuming it to be a *7 w *bbgvjptz(gk6ich lu0+9perfect egw+ lb96*g*u7v(0kzjt b ihpc 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,nsz+3 akfo*cp49;xc t a 70-kg 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 cl)u i 8 uu9t9p6ton/dmeiff and falls a vertical height of 140 m before striking the ground. Estimate the temperature rue6i8d)um 9no tu /tp9ise of the rock if 50% of the heat generated remains in the rock.    $C^{\circ} $

  A 2.3-kg lead ball is dre1:mzl:4l xn iopped into a 2.5-L insulated pail of water initially at 2 : llzei4m1:nx0.0$^{\circ} C$. 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 js / uzrl,26b qy-zzarjcsl1 :jlw036u acket 3.5 cm thick with total surface arezl:6b0jrq a-3j/ zly6 2slwuzsu1 cr,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 average mez8qz g.cd.mhh27rac( 9jxl) ktabolism 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 int / u.c4f-q.xcdfsa pi5bu82zwerior of the body to the surface. Assume that the thickness of tissue is 4.0 cm, that the skin fd4z.wbpc5xs ui / 8.fcqa-2 uis 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 (assum) bct,9zmvpv- i7hp6 ubd*q:me conductivity of air) and areadmvp 9p7m6*,:) bzcb uvq- thi $410\,m^2$ 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 travelingm pt; , 2we91tu/qig-*o )oy;hotnwdb 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 account ri k8cb *:nmcb/9iw epvo41y.wadiation from the leaf to calculate how much water must be transpired (ewp b1k.eo98c m/*4wc inv ybi:vaporated) 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 ib7q;-l02ue2 u md e g9yfbymm*nitial temperature was u *0m9fbqymleg;7m2 bdu-y e2-125$^{\circ} C$ 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 Earvmx: w/t-v/qyth’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 p9 hty *dk1jok4uaxa+) *nf, msquash (Fig. 14–22), two people hit a soft rubber ball at a wall until they are about to drop due to dehydration and exhaustion. Ash*pmj*9,yf4 x n ka) t1okdu+asume 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 fin36o+ phbpgt u-al result when equal masses of ice at 0$^{\circ} C$ and steam at 100$^{\circ}C $ are mixed together?

  In a cold environment, a person can lose heat by condub(o04lud vpo e8tj(pib) ::oj ction and radiation at a rajl(::4)pi8ov(tbbo jue0odp te 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”w2 w yaf n b4/u 8/(pez;zjxevv46i2fi left in the 50-gal (185-L) z4 bi /faej xu4w/nv2(zi; pvwy62ef8water 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 glass1.m cazt q3/1vu cmd3g 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.    $^{\circ} C$