What happens to the work done when a jar of b2 ijnz md u:.)scy9kc(zrg1*orange juice is vigorously shaken?

When a hot object warms a cooler object, does temperature flow between themo3p6 fhezj)y (? Are the temp (jpfyo)he6z3erature changes of the two objects equal?

(a) If two objects of differenoj* k +gu,pq.;.wvmte t temperatures 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 ob+o;.*gt,kupe .qvm jwjects are the same? Explain.

In warm regions where tropical plants grow but tfmr 74k8xt 0fvhe temperature may drop below freezing a few times in the win78vk ff04mxrtter, the destruction of sensitive plants due to freezing can be reduced by watering them in the evening. Explain.

The specific heat of water is quite largep4)nnkrd6rpi w1n l.0 . Explain why this fact makes water par1. l4r6dwpk) nnnrp i0ticularly good for heating systems (that is, hot-water radiators).

Why does water in a metal canteen stay cooler if the cloth jacket surrounding sxy 8r7 nirjp:d.v5a7the v5x. riays 78d p:nj7rcanteen is kept moist?

Explain why burns caused by steam on the skin are ofz0.f n9+ifs cdten more severe than burns caused by water z+9csi0nfdf.at 100 $^{\circ} C$ .

Explain why water coo*bic/lq8ys) 7nr ot:qls (its temperature drops) when it evaporates, using the concepts of latent lco b8q tns:iq)7yr /*heat and internal energy.

Will potatoes cook faster if the water is boiling7 18stxkk- jmf faster?

Does an ordinary electric fan cool the air? Why or why no mdtl*rkn:ja 1kni9 ,h+6z jf1t? If not, why use it?

Very high in the Earth’s atmosphere, t 8;8tycx/ / pkteya7e7dz) ctthe 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 covera ltmra9ph )4vx0hb -+ing themselves with snow. Why would tbp4a9 lv-+r 0mhat)h xhey do that?

Why is wet sand at the beach cooler to walk on 02p 6hp,hj vam(1aszsthan dry sand?

If you hear that an object has “high heat content,” does th .6bj opbbca66.wu+ jrat mean that its temperatur cb6b.a+pjor 66uwbj. e is high? Explain.

When hot-air furnaces are used to heat a nqn0in) c0 ;3bxw -/ 64iaezysurkl:nhouse, why is it important that there be a bc:3k-n6lni/;i0rnyu s04xqezaw n)vent for air to return to the furnace? What happens if this vent is blocked by a bookcase?

Ceiling fans are sometimes rever6y+7bbuq l f29drhu9 zsible, 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 winteuqbr 2y6ld+ 9uf b9h7zr?

Down sleeping bags and park .ufptsthn9bm)m u,k01u,p(a as are often specified as so many inches or centimeters of loft, the actual thickness of tmuh f1ps9,n p0k., ut(muta)bhe garment when it is fluffed up. Explain.

Microprocessor chips have a “heat sink” glued on top that look unum2xd.9+l 0,vur ews like a series of fins. Why isr0.u9mlenvuxw+u2d , it shaped like that?

Sea breezes are often encountered on sunny days at the shore of a larg6k9l, tzg9up pe body of water. Explain in light of the fact that the temperature of the land rises more rapidly than that of the nearby wategtz 99p6 lpk,ur.

The floor of a house on a fo3lz0qo.sw 3 koundation under which the air can flow is often cooler than a floor that rests directly on the ground (such as a concrete3ok0.ozqs3lw 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 alwaim -btmfqpp;.+e9p 7sys taken with the thermometer in thfbp-;tpi79 s mpqe.+m e shade.

A premature baby in an incubator can m1-rnt7fy a-n be dangerously cooled even when the air temperature in thna 1nftm--ry7 e incubator is warm. Explain.

Why is the liner of a thermos bottle silz ht 44)5p0 wdwcql bp3wlh.7gvered (Fig. 14–15), and why does it have a vacuum betweenw3 0.hhzpwq4wpd tc4)7l blg5 its two walls?

Imagine you have a wall that is very well insulated — it has a very high theu3waiso c- 0.7stzc w/rmal resistan wacs0t iuc/.s3o- wz7ce, $R_1$ 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 procenzqc ww(4tpgn:p pey)n.4 i.:sses: (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) ey pg(i.zpn wnq: n44c:p )t.wthe 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 heatibt3 3p43yjxd* av :rl than a piece of shiny metal. Yet the wood feels less*bl34p:ya 3dv 3 ixrtj hot than the metal when you pick it up. Explain.

The Earth cools off at night much more quickly when the weather is (g+ *eyii bh.gclear than wheg+ib. e(*hg iyn cloudy. Why?

An “emergency blanket” is a thin shiny (metal coatedb ; ixjhsq9e* 0z9fum 3(snll-) plastic foil. Explain how it can help qisnz3-* lh09;9 mx se bfj(luto keep an immobile person warm.

Explain why cities situated by the ocean tend to have less extreme temp)2 (jpfo.;.f am0giymusj h+ieratures than inland citi;f )fosm2.j iuap(i 0jmy+gh. es at the same latitude.

  How much heat (in joules) is required to raise the temperafpo 5sfe+6 9mc. +cxzjz.xf1q ture of 30.0 kg of water fj. + xf. ps9c15x6+foqcez mfzrom 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 initially4 v,yeyazqtx8t wy3+,k rw 2;s aty,qr4vywa3ttxze k+ 82wy,s ; 10.0 $^{\circ} C$ ?    $^{\circ} C$

  An average active pen suej3hvs/3ny1 3yy7rson consumes 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 (Btu) is a unit o htkyt kdux7 r,dhcr-8,c2,es 6n+f) rf heat in the British system of units. One Btu is defined as the heat needed to raink, efhr-y,dxt7hc8r tk6,cr+d2s )use 1 lb of water by 1 F $^{\circ} $ . Show that
1Btu = 0.252kcal=1055J

  A water heater can g+k6ttt,j 4ky zenerate $32,000\,kJ/h$ 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 itsaw )q o*.6.f(z+rgd i.v5us m8uwthh will take to heat a cup of soup (assume this6moru f*uhgqvh . +d wsi5.(wasz)8t. is 250 mL of water) from 20$^{\circ} C$ to 60$^{\circ} C$ .    min

  How many kilocalories are generated when the q* j f4;qoek)sgc4p9 i1/fno ibrakes are used to bring a 1200-kg car to rest from ag9jfq4)e/k n*ocisf1iq4 p o ; speed of $95\,km/h$ ?    kcal

  An automobile cooling system holds 16 L of water. How much heat does it abo0e1k0 n) kbl0g htcgm(l0x /ssorb if its temperature rises from1 lckn) 0(s0o mk/xg0 e0bthgl 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 nee1, )o8bxs px ls ik*jz3e2bq4ufy*cp;ded to raise 5.1 kg of the 2f1; pqj,sibx 8x* u34oye cbpz*k) lsmetal from 18.0$^{\circ}C $ to 31.5$^{\circ} C$ ?    $J/kg\cdot\,C^{\circ} $

  Samples of copper, aluminum, and water experience the same tempw-ay; 3ztonhr9,0 vyaerature rise when they absorb the same ;t3vya hon9-,azr 0w yamount of heat. What is the ratio of their masses? [Hint: See Table 14–1.]$m_{Cu}$ : $m_{Al}$ : $m_{H_2O}$ =    :    :   

  A 35-g glass thermometer rerp+ uv;at:s (be(uwo28npu y*ads 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 equ/s :q(g+mmleooxdoy3e;m:h. xp a)x 1ilibrium 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 (maz 6fg0rd:t,f4 /z mjq)bqd0 aiss = $0.4\,kg$) 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 38c teqk lhsrw4l,5pdy v*s5-/ 30$^{\circ} C$ 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 vpl (flttr2)oyqmpu q(,1 mh 9cl8l-8to a boil 0.75 L of water initially at 8.018v(l qc2pf r(m -llpt8uhy mq 9tlo,)$^{\circ}C$? 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. 8)jev-eu1m i qv3sp9an2z1 alA 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 calorime-e1pa93avszlni1)2 q j ue8mv ter 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 iron3zjiqw:g l11j;6jjd c y xj-*u 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 ha35 zhi t o;z8 va,y;l15,rhdunj zm)jommer 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 od s-f6qahet (- 1 0x r7yn,ufeybh-7jhf heat needed to raise itsbaf7ee -06dn,j q- (y7h h1-yxfutrs h 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 silver that is initial. lbt.c24xfanly at 20$^{\circ} C$?    $ \times10^{6 }\,J$

  A 0.095-kg aluminium sphere is dropped from the roof of a 45-m-high bjz9f.b )e3s)rm ,zr lcuilding. If 65% of the thermal energy produced when it hits the ground is absorbed by the sphere, what is its temperature incre recfmz 9sbr,. lj3z))ase?    $C^{\circ}$

  During exercise, a person may givejrqemhb 15f-1 off 180 kcal of heat in 30 min by evaporation of water from the skin. How much water h-f1rm15jq hebas 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 itj)6l t9c2 jxvxs melting point is dropped into an insulated container of liquid nitrogen. How much nitrogen evaporates if it is at its b2 vc9xl)xjt j6oiling 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 freezer1cvsp7un 68 t) cpp-v zoats(4v/k fe( 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 mamae / qihsghzzy) ; v7/e-g7w5ss 230 kg contains 830 kg of water at 18$^{\circ} C$. A heater supplies energy at the rate of $52,000\,kJ/h$ How long does it take for the water
(a) to reach the boiling point,$\approx$    h (Round to one decimal place)
(b) to all have changed to steam?$\approx$    h (Round to the nearest integer)

  In a hot day’s race, a bicyclist consumes 8.0 L of watlen /w b8hv+8ver over the span of four hours. Making the approximation that all of the cyclist’s ener/nblv + w88vehgy 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 at0 j m 2mfcukwv.yz1*9q 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 mercurpy:ne,ac* h2g y 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 atay3) iev4 (snj92nds p $250\,m/s$ 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 movigfdi,-r4f5bk6luh - ung 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 not1f9t fh p24mmxq (w1hves that the 8.2-g lead bullet that was stopped in a doorframh mfh1pt149 wxvm2qf (e 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-lon k nu1m9wg +da:mmiwqe4f ;j-:g aluminum rod with a diameter of 2.0 cm is kept at 460$^{\circ} C$ , and the other is immersed in water at 22$^{\circ} C$ . Calculate the heat conduction rate along the rod.    W

  Calculate the rate of heat flow by conduction in Example 14–10, assuming that thlnsog(y9 c)w6e6vx2cere are strong gusty winds and th2 yx sl96evow c()gc6ne external temperature is -5$^{\circ} C$   $ \times10^{4 }$ W

  (a) How much power is radiated by a toeyq*ou akud-me:5 l z n0*18tungsten 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,k,pe6wub x 4c 200 W of heat flows by conduction from the blood capillaries beneath the skin k bwexp 4,6uc,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, sharvd c0 0fsqd61de a 12-cm-thick brick wall. Because oc s0vddf 10d6qf a number of 100-W lightbulbs 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 Sunxv./gk ;xge(unly a: 1 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 length adi69 -z,wpwr x9vwn i.oue79f3wb: vknd cross-sectional area are attached end to end (Fig. 14–18). The 3.x9p7evfurww:i ,9w 69d bvk- nowi zcopper 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 e2n 1jke:kel )the whole Earth receives ener1eelk) :ek2jngy 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 acszw 9*js;u e) 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 azuc*9 ejs ;)swnd outer surfaces of the glass?   $^{\circ}C $

  Suppose the insulating qualities of the wall of7 z,r utts6 mkbxnke*;ha65 oge2b kb;h(7z(p a house come mainly from a 4.0-in. layer of brick and an R-t 776abkh uxhk*srz ;e5po;((,k znbbgt6me219 layer of insulation, as shown in Fig. 14–19. What is the total rate of heat loss through such a wall, if its total area is $240ft^2$ and the temperature difference across it is 12 $F^{\circ} $?    Btu/h

A double-glazed window has two panes of glass separated by 5c 5 z2oemktvyg;t rv/af(i)/an air space, Fig. 14–20. (a) Show //2vtm5fr(e; t )iz5 cvgykao that 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 lonku*mk e1abiy qarq4; k*:6ou7g should it take 11.0 kg of ice at 0$^{\circ}C $ to melt when it is placed in a carefully sealed Styrofoam ice chest of dimensions $25\,cm\times\,35\,cm\times\,55\,cm$ whose walls are 1.5 cm thick? Assume that the conductivity of Styrofoam is double that of air and that the outside temperature is 32$^{\circ} C$.    $ \times10^{4 }$s

  A soft-drink can contains abokpw+ c 6up* kle4,ax-jut 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 mucho0y:804:adkr/h*nvjsrs r uf thermal energy is contained in the world’s oceans, estimate the heat liberated when a 4s:v k/0ua:y *ojf0sh8n r rdrcube 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 teste82b/xu13vyed2r2e l uzb+cim d 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.xle2v 12/3d82ze+ imcb ruu yb 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 space by the Sun7kp(u6ms n.myoz* h 4br/5lrr , assuming it to be a perfect emitter atz 4symp*ok7h 6lr rr/(nu5m.b $T\,=\,5500K$ 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 perxjf*1w8pv,fj d, 5 vojson 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 cliff and falle(e(etg:02udsku n wh0f d:sp n+ 0f/ss a vertical height of 140 m hup f s0(enfse:0+n0w( sgk u:e2td d/before striking the ground. Estimate the temperature rise of the rock if 50% of the heat generated remains in the rock.    $C^{\circ} $

  A 2.3-kg lead ball isjqo.1/h r plqq9/j*foys p1w: dropped into a 2.5-L insulated pail of water initially at *9o p r1p qlqw s:q.j1y/fj/oh20.0$^{\circ} C$. If the final temperature of the water–lead combination is 28.0$^{\circ} C$, what was the initial temperature of the lead ball?    $^{\circ}C $

  A mountain climber wears a goose down jacket b :huz/,bl:u ;5. q4udk ul/:jy lbaln3.5 cm thick with total surface arelu //zh qal;u, bu:blb und54:: y.jkla $1.2\,m^2$ The temperature at the surface of the clothing is -20$^{\circ}C $ and at the skin is 34$^{\circ} C$. Determine the rate of heat flow by conduction through the jacket
(a) assuming it is dry and the thermal conductivity k is that of down,    W
(b) assuming the jacket is wet, so k is that of water and the jacket has matted to 0.50 cm thickness.    W

  A marathon runner has an average metabolism rate of axvg(lf6; qq0o* 3mqy vbout $950\,kcal/h$ 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 6o 5co+ t9a7wgkxfq1 mcan be conducted from the interior of the body to the surface. Assume that the thickness of tissue is 4.0 cm9m go7f6 wcq5txko 1+a, 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 (assume conductivity of air) and s)zx3/pu vnow0-i5kbarea)z3bvou/ x-kn0 psi5w $410\,m^2$ 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 travelic3 di n *jhgvdo+/5ci.947fqa tao0syng 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 5.3 lra.nxm6e f8, take into account radiation from the leaf to calculate how much water must be transpired (eva3.mn6x r.lef aporated) by the leaf per hour to maintain a temperature of 35$^{\circ} C$.    g/h

  An iron meteorite melts when occ d/el+49luf-bi8 ko :2 l lg-6rzuzit enters the Earth’s atmosphere. If its initial temperature was -du8o l:9gbk6 ic+/lu e2z4 lolcfr- -z125$^{\circ} C$ outside of Earth’s atmosphere, calculate the minimum velocity the meteorite must have had before it entered Earth’s atmosphere.    m/s

  The temperature withi0gyw+ sq7k,k08bj v9 .trnhwtn the Earth’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 squash (Fig. 14–22), two people hit a socd*g-eq9 3 +rb xt3:fypd vb3 7bafhl3ft rubber ball at a wall until they are about to drop due to dehydration and exhaustion. Assume that the ball hits t f -fe3*q79+3 bvyrt l:pxach dbg3db3he wall at a velocity of $22\,m/s$ and bounces back with a velocity of $12\,m/s$ and that the kinetic energy lost in the process heats the ball. What will be the temperature increase of the ball after one bounce? (The specific heat of rubber is about $1200\,J/kg\,$$\cdot\,C$)    $C^{\circ} $

What will be the final result when equal masses hx *f(s4ss6(rvgts+kk+5 hg;zs )c yrof ice at 0$^{\circ} C$ and steam at 100$^{\circ}C $ are mixed together?

  In a cold environment, a person can losev0udp ,k2c -k uhhkro4k)7.yc heat by conduction and radiation at a rate of about 200 W. Estimate how l4c ., k7ucr)k0o2dhpu- khyvkong 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 vld6c7m9i kvwecs;-:the 50-gal (185-L) water heater. This suggests that the tank has emptied and ref eic6v:7;dsvcw9l m-k illed 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 surfac9sq 4g kpz4:kae 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.    $^{\circ} C$