What happens to the work done when a jar of orange juice is vigorousm 7dbzryj9qb4s(;z c3ly shaken?

When a hot object warms a cooler objecoh,(t1ukl bdditq a q+m)8k:-z1 +fhr/b n;uht, does temperature flow between them? Are the temperature changes of the twd1 hlqa , hti:kt uk +/f;omnr)-qu(bd+h b81zo objects equal?

(a) If two objects of different temperatures are placed in contact, will hntm4bbfoh/oy6 y5 + y s6z+xb-eat naturally flow from the object with higher internal energy to the object with lower internal energy? (b) Is it possible for he+fyb6oh/-ob nbx zy 4mt+ s6y5at to flow even if the internal energies of the two objects are the same? Explain.

In warm regions where tropical plants grow but the xk4ih00d. 7 rdpq jy60c7pjhotemperature may drop below freezing a few times in the winter, the destruction of sensitive plants due 06jp7o qcki hp407 hd0jrdyx.to freezing can be reduced by watering them in the evening. Explain.

The specific heat of water is qui/wuvdbw4h; za5 pt a2o,x7km5te large. Explain why this fact makes water particularly good for heating systems (that ipz wdo,hmb24wk5a/xu t;a5v 7s, hot-water radiators).

Why does water in a metal l3bvymf *h6c. canteen stay cooler if the cloth jacket surrounding the canteen is kept lf vbm6y.h* c3moist?

Explain why burns caused by steam on the skin are oftc t8 p )ofvc*:tr5dyq1-ak6/cdapx,s en more severe than burns cauraf8cv-)*x65t/pt ad cq d scy1,ko: psed by water at 100 $^{\circ} C$ .

Explain why water cools (its temperature drops) when it evaporates, ut4bm. on)dy0qe 8l. ,/jc; pkyp9nerxsing the concepts of latent heat and internam8 tklp.9cb0rxjyy;/pne) d q,4e no.l energy.

Will potatoes cook faster ifj06gtp0br*v.6g 8 jo udcy5gl the water is boiling faster?

Does an ordinary electric fan cool the air? Why or why no a*s92rrqpd( eebd vpgqy.* r .ma4./pt? If not, why use it?

Very high in the Earth’s atmospt3dw)610wfgc;k d kzurdz27r th ei 76here, the temperature can be 700 $^{\circ} C$ . Yet an animal there would freeze to death rather than roast. Explain.

Explorers on failed Arcti( zmb6 wjyhc4/q*ng 8yc expeditions have survived by covering themselves with snow. Why would they do that /8w4nbzyjc6 *qmg( yh?

Why is wet sand at the beach cooler to walk on 4cj 3go sis*w;than dry sand?

If you hear that an object has “high hea-2 edy:sv0ej1 ns c/wbi0l5 int content,” does that mean that its temperature is00vb5ie: yj-n s2e nc1s w/ldi high? Explain.

When hot-air furnaces are2fnol b5js f0: used to heat a house, why is it important that there be a vent for air to return to the furnace? What hapoj 0fn:f5l 2bspens if this vent is blocked by a bookcase?

Ceiling fans are sometimes reversible, sjxsj,c n 9o9gw9j;ay +o that they drive the air down in one season ,j; jx99gn wc s9yoja+and pull it up in another season. Which way should you set the fan for summer? For winter?

Down sleeping bags and pars /v)wxx9 wa0qkas are often specified as so many inches or centimeters of loft, the actual thickness of the garment when it is fluffed up. Explaiqx9a)wv0xw/s n.

Microprocessor chips have a “heat sink” glued ug/ txg:/ lx:p. qjr:qon top that looks like a series of fins. Why is it shaped like th/g j ql::qt/g. ux:rpxat?

Sea breezes are often encount y;k oi gwvt;yqvo -44mm1cf)8ered on sunny days at the shore of a large body of water. Explain in light of the fact that the temperature of the land risiyyk;c q1t4o;f owv)- vmg4 m8es more rapidly than that of the nearby water.

The floor of a house on a foundation under which the air can flow is 7lbm betfgl zi4o:s5(o q* a4(often cooler than a floor that rests directly on the ground (such as a concreti( fb:z * solmt5baqe7gol4(4e 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 thermometer88 zit(x /pcs,2f-pdf* mqpjx in the shadpxji2p,xc( qst8f/8 -dp*m zf e.

A premature baby in an incubator can be daneg5vr32hvspj x8 u7d ,8p-kz igerously cooled even when the air temp5-7zxvkvihs , djpe 8r28pgu 3erature in the incubator is warm. Explain.

Why is the liner of a thermos bottle s :ern dv2.2nmeilvered (Fig. 14–15), and why does it have dev2m n nr2:e.a vacuum between its two walls?

Imagine you have a wall thatq)a rv(,asem:szz* w+ is very well insulated — it has a very high thermal resistancq zsz *r)+ ,wvs:ae(mae, $R_1$ 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 p -um2hibu-r 1hrocesses: (1) 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) the mechanism(s)ru2-m- iu 1hhb: 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 piet-f2 ote (rl;bce of shiny metal. Yet the wood feels less hot than the metal when you pic te;tl2b(orf-k it up. Explain.

The Earth cools off at night much mou op;-b01h2mxk;j u vlre quickly when the weather is clear than whenl hpo1v-0 b;uk ;jux2m cloudy. Why?

An “emergency blanket” is a thin shiny (metal coated) plastic i)rso( ,bxgj 22f8as dpx0 3qtfoil. Explain how it can help to g)tr s02jpf8 oib,a2x qsd3( xkeep an immobile person warm.

Explain why cities situatedz6hrs3m sis1l2f-iqt2qm5 wn: av 8n2 by the ocean tend to have less extreme temperatures than inland cities at the same 216l n tsvm8q rq5-3z mi2:nia sws2fhlatitude.

  How much heat (in joules) is required to raise the temperature of y:/hzl b3(ywc7 r rh4;ubgs7z 30.0 kg of water from 73;4wzs b:y7gb(yhl ucr/zhr 15 $^{\circ} C$ to 95 $^{\circ} C$ ?    $ \times10^{7 }\,J$

  To what temperature will da vrgxexs l/50.9t.zbir-7+s fdso+7700 J of heat raise 3.0 kg of water that is initially at75i efovzr .x+0.a-gss/ td9sxldr+b 10.0 $^{\circ} C$ ?    $^{\circ} C$

  An average active person consumea7js lt 6p3b gtp)-nv 2)jcpp3s about 2500 Cal a day.
(a) What is this in joules?   $ \times10^{7 }\,J$
(b) What is this in kilowatt-hours?    kWh
(c) Your power company charges about a dime per kilowatt-hour. How much would your energy cost per day if you bought it from the power company? Could you feed yourself on this much money per day?    dollars per day

A British thermal unit (Bt7-,m aqsfd7spybm+* ou) is a unit of heat in the British system of units. One+m,sbs7*aq y 7 od-pfm Btu is 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 generate 0,83psxg dsytgo .k +hjrv)n/ $32,000\,kJ/h$ 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 ho,lpt wv(q:j 4hw long it will take to heat a cup of soup (assume this is 250 mL of watertv pqjw,:4h (l) from 20$^{\circ} C$ to 60$^{\circ} C$ .    min

  How many kilocalories are generated when the brakes are used to s x5q0dc -pff+lnp8xgkx/y;3 bring a 1200-kg car p;0ps-+3d/yxlknxf gfx58c q to rest from a speed of $95\,km/h$ ?    kcal

  An automobile cooling system holds 16 L of w jm08gu4 xbnef0ua +cp(f,j0iater. How much heat does it absorb if its temperature rises from 8f+u en g0ajjbmfxcp,0 i 4(u020$^{\circ}C $ to 90$^{\circ} C$?    $ \times10^{ 6}\,J$

  What is the specific heat of a metal substance if 135 kJ of2w9cxdi v3 x. yr5pol; heat is needed to raise 5.1 kg of the me3y5 lv2;w crx.xd op9ital from 18.0$^{\circ}C $ to 31.5$^{\circ} C$ ?    $J/kg\cdot\,C^{\circ} $

  Samples of copper, aluminum, and water experior mpc;oa 2hdn4:6 zfon:zzjm.:: g8zence the same temperature rise when they absorb the same amount of heat. What is ;j md4z:n8m:.zg fo:ph2oacz: z6ronthe ratio of their masses? [Hint: See Table 14–1.]$m_{Cu}$ : $m_{Al}$ : $m_{H_2O}$ =    :    :   

  A 35-g glass thermometer rey z;ji.y +avy1ads 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 equilib sxl8 y2;xnhz:rium temperature when 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 (mam6uffle6 :am-/ / d- u eqre ent.ol(w561xnwcss = $0.4\,kg$) 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 iss 4h3ye1ewqj u:3ur, n 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 u3vnysh2.ac 10.75 L of water initially atc2a3.1yh v sun 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 following measurements.caw5d9t dc 9h* 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 dawd95* c9 cht2.00 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 ofs o(byzn;sj6:e h0o) b iron at 180$^{\circ} C$ is placed in a 95-g aluminum calorimeter cup containing 250 g of glycerin at 10$^{\circ} C$ , the final temperature is observed to be 38$^{\circ}C $ . Estimate the specific heat of glycerin.    $J/kg \cdot C^{\circ} $

  The 1.20-kg head of a hammer has a speed ofci55,2euvp-qjm tl+k $6.5\,m/s$ 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, ofb(v7* l)zry vm an object is defined as the amount of heat needed to raise lr7 )mvvz* (ybits 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 of7 bkp-e:tjyb/ 2/d vja silver that is initially at 20$^{\circ} C$?    $ \times10^{6 }\,J$

  A 0.095-kg aluminium sphere is drocyhl8c lzd7i 0/5ew,t pped 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 its temperatu z,h8yl/70id ew 5cltcre increase?    $C^{\circ}$

  During exercise, a person may give off 180 kcal of heatp ;emi+fztr45,9ops8 uqyysu* 1zq+g in 30 min by evaporation of water from the skiu 8+;o4q fry qu gzpsm*ei 15+t9s,pzyn. 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 insulatebp j 0-ojxcsl/y,d(3cd container of liquid nitrogen. How mxyjc cd/ ,bosl-3(0p juch 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 f+g7y d;2xfp vm8e h+ 7gowe9ijrom 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 kgt. kbf.aqq )r: 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.nn 3/gex/f:ej 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 efficiencj/: g nfn3ex/ey 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 a /i.xdt 8 w.tacv;vgd20 taj0vt 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 merhp , c/e,--xihfx7t m5yd+ih6n *mdikcury 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 travelingpa1- aa.hy:. y+6str- ltfzag)4su oj 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 movix4 k7 54aup-f4iveag:6gb*q+a neolsg 8i uo)ng 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 foren 96 fk2cqq ;irifz:0(rn dr)wusic investigator notes that the 8.2-g lead bullet that was stopped in a doorframe apparently melted completely on impact. Assuming the bullet was 6 cwru (q2f k ;rznir)f09q:difired 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 n0kr7:3qd-u) yi sxh p8 tdym+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 4( z mk,dguuelk35sw;flow by conduction in Example 14–10, assuming that there arz mu,k 4eludg wk5s(;3e strong gusty winds and the external temperature is -5$^{\circ} C$   $ \times10^{4 }$ W

  (a) How much power is radiaru2 vhxylnu/1s6y0w4 ted 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 su*jsvk: 2a)jikin. Suppose 200 W of heat flows by conduction from the blood capillaries beneath the skin to the body’s su vsk: )ijau2j*rface 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 siderzz; 5n7dqw/z, share a 12-cm-thick brick wall. Because of a number of 100-W ligh/qw5zz7n rdz ;tbulbs 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 blokqjqh;jw8r,wbmb so3a*2+( a ck of ice at 0$^{\circ} C$ with a flat horizontal area $1.0\,m^2$ and thickness 1.0 cm? Assume that the Sun’s rays make an angle of 30$^{\circ} $ with the vertical and that the emissivity of ice is 0.050.    h

  A copper rod and an aluminum rod of the same length and cross-sec5w3p6xo+ sudl-5q r sdtional area are attached end to end (Fig. 14–18). The copper end is placed in a furnace maintained aq pslwdd-+sr65x53ou t 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, estimatei,4g /tz uadqt)mz(k6 the rate at which the whole Earth receives energy from the q/ 4d mtazk (,u6)zigtSun.    $ \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 aqql f4fq+w 780j t.)2sscn jc,e zys8x glass 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 outer qjs7xzfqs)4 jnwsc8,tlfcq82e .+ 0 ysurfaces of the glass?   $^{\circ}C $

  Suppose the insulating qualitij8tcq*d/zmklte+s:: dh /6nlevnem 3 a6 2; hmes 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 t8te :/q+ mvcz6m /d;3lm6*snlna:hdteje k2h he 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 p8,a7xzxpd(-d vlupt2 anes of glass separated by an air space, Fig. 14–20. (a) Show that the rate(zdx7 8 v2ldppux-a,t 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 sh*h3y70 (tc pjdc niighi06ro (ould 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 conxki1k7 r,k vs1tains about 0.20 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 thermard 6v2*h1u7: (sivoq q /eqkwyl energy is contained in the world’s oceans, estimate the *q6s vwk2v: /rqo(q7h1yied uheat liberated when a cube of ocean water, 1 km on each side, is cooled by 1 K. (Approximate the ocean water as pure water for this estimate.)    $ \times10^{ 15}\,J$

  A 15-g lead bullet is teste8: 62s*cs uj sve0swdzd by firing it into a fixed 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 beeu:s6 *evs28sc jd0ws zn reached, the system has a temperature rise measured as 0.020 $C^{\circ} $. Estimate the entering speed of the bullet.    m/s

  (a) Find the total power radiated into space by the Sun, assuming iye db:6f xhf/;t to be a perf yb;e/fxh6 d:fect 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 person may generatr -6s.zmbe)lut8quqi ,3t-l ee $200kcal/h$ Assuming that 20% of this goes into useful work and the other 80% is converted to heat, calculate the temperature rise of the body after 1.00 h if none of this heat were transferred to the environment.    $C^{\circ} $

  A 340-kg marble boulder rolls off the top of a cliff and falls a vertich ynexr ( 55azcnrv,c+d 623izal height of 140 m before striking the ground. Estimate the temperature rise of the rock if 50% of 5 +x n(z ccdrn2razeiv,5hy63the heat generated remains in the rock.    $C^{\circ} $

  A 2.3-kg lead ball is dropped into a 2.5-L insulated ,gmdwfnr, x:mz2); lepail of water initially at 20.02l)m:mxndwz egf ;,r,$^{\circ} C$. 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 wi7q v, o77xh0otas ;juqth total surface are7a,;7 oot 0qv7uxs qjha $1.2\,m^2$ 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 metabolisn3y6t 5s**sgy)twh ,4pot zx1oqg4zvm 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 the8idq autogs 76q-43ui p 9n6km0p/eyx interior of the body to the surface. Assume tispuq3a96dox p84 ing -6 7ty0uqemk/ hat 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 wam44d h- 8ecgnzo/57sacxyae 0lls 17.5 cm thick (assume conductivity of air) and areaa4 754m8xay 0cnod/h ecezg- s $410\,m^2$ 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 traveling at v,e ll32v86cop9fwaq $220\,m/s$ 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) /j)tg5s pquwb(sjcu6;yt5 8 yin Problem 58, take into account radiation from the leaf to calculate how much water must be transpired (evaporated/t8ycj5suqp)6;su5 t(ybg wj) 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 io.b jk;;y. xhih2 x* y/ug;enatmosphere. If its initial temperature .ihk i2yox;h ;uyg;xbe/j n*.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 increases ab t;3o dsm rwb+1t4v4is-pvnj8out 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 soft rubberp(zyk8i 7nco)q2 nkw.;mn3ri ball at a wall until they are about to drop due to dehydration and exhaustion. Assume that the ball hits 8 kzcniq3kny i 2wr.mpno7;() 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 finanvcl)3h*)ky o l 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 conduction and radi58pjrna hp q/ 5p3+fqration at a rate of about 200 W. Estimate how long it would take for the body tempe5 58q aq 3pjrnf+hpr/prature 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 1 eyi, -j r0mahi0+e.hbgdy(a50-gal (185-L) w0h ia(+0r.h bjyeymid a1eg,- ater 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 surfacec e 9u:zpca2(i3oj*qd 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.    $^{\circ} C$