What happens to the work done when a jar of orange juicewm i lu-5n-*ho is vigorously shaken?

When a hot object warms a cooleee nl... but hr-t*)/ti6iiinr object, does temperature flow between them? Are the temperature changes of the two object/.b.-6i i t ri)h t.tnnueile*s equal?

(a) If two objects of different temperatures are placed ll-a99difie7 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? Explailiad9 l9-ef i7n.

In warm regions where tropical plants grow but the temperature may drop o5kw .9psgzu89kx eat w0u)1dbelow freezing a few times in the winter, the destruction of sensitive plants due to freezing can be reduced by watering them in the evening. Expwz09ug.xe dk)8a wt5ko9s 1p ulain.

The specific heat of water is quite large. Expl x o 20fe.+-. v9nvb/xghduymfain why this fact makes water particularly good for heating systems (-v/.eyf0fxm9 nb h2vxo gu+d.that is, hot-water radiators).

Why does water in a metal canteen stay cooler if the clot dq(z jh:hk ;xkdpkin) g,,*d2h jacket surrounding the canteend,h;z2(j :x d) *dkhqn igkp,k is kept moist?

Explain why burns caused by stefvllbph1 c.k 1,b.fxmtf.adai* ) k .+am on the skin are often more severe than burns caused by mh.l kfbk. pa.tvfalx)bid,f c.1*1+water at 100 $^{\circ} C$ .

Explain why water cools (its temperature drops) when it evaporates, using t 4 9enroolgu18.c r7w:hmd:(g )pamg rhe concepts of latent heat o: ch (e8u1d .a:rlmg)g94m7op rwgnr and internal energy.

Will potatoes cook faster if the water is boiling fastemjt +p,)b4ua 3k6ry xar?

Does an ordinary electric fan cool the air? Why or why not? If n+y542 seud umu9ei)zg ot, why use it?

Very high in the Earth’s atmosphere, the temperaturev9j)ktam ;f oyz2v1 cg4kb 89w can be 700 $^{\circ} C$ . Yet an animal there would freeze to death rather than roast. Explain.

Explorers on failed Arctic expeditions have surviv o.zv xn-h6(;8tjtz xaed by covering themselves with snow. Why would they dott;zn. 6jx- zo vh(ax8 that?

Why is wet sand at the beao 5iqqcshl8c :py/:(c9 d*qytch cooler to walk on than dry sand?

If you hear that an object ha1dqbzzy (h)- os “high heat content,” does that mean that its temperature is zyh-( q)1 bozdhigh? Explain.

When hot-air furnaces are used to heat a house, why is it z7rdqzf, kevk g6 5.x8important that there be a vent for air to return to the furnace? What happens if this vent is blocked by a bo ,5. kzxe7kqrgvf8z6dokcase?

Ceiling fans are sometimes reversible, so that they drf 1ca9:zq5itik: f)o gwe.wl)ive the air down in one sease f:5q9l1.gaoiiw):ftz w )ckon and pull it up in another season. Which way should you set the fan for summer? For winter?

Down sleeping bags and parkas are oftenfy(b mdb (ep(l0y- :vr specified as so many inches or centimeters of loft, the actual thirfdy-(p (m0bey:l( bvckness of the garment when it is fluffed up. Explain.

Microprocessor chips have a “heat sink” glued on top that dxj(d76to k;q looks like a series of fins. Why is it shaped lik7xq6t;( d dojke that?

Sea breezes are often encountered on sun(ar.5*vnlbx v ny days at the shore of a large body of water. Explain in light of *rlvxa.vb n5 (the fact that the temperature 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 flow is often cool,-k -4xhvxkk9 b0j1 qe:1zof zo ewby8er than a floor that rests directly on the ground (such as a concrete slab fo-qzey k1xjf k bhbw94k- e:v1,o80zoxundation). 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 an o2yn g3wd6i3k; l(dvlways taken with the thermometer in the shadio2(w3 d3l;d n6gyknve.

A premature baby in 4oscu1l 1 4c ;p)ip,t4emjfrman incubator can be dangerously cooled even when the air temperature in the itmf i14mclp44), oj;pus er1c ncubator is warm. Explain.

Why is the liner of a thermos bottle silvered (Fig. 14–15), and a9nj941 xl6,zeth tx6lk n6auwhy does it have a vacuum between its two waz,at ujltle 64xk9n1a6xn9h6lls?

Imagine you have a wall that is very well insulated — s) i bnnf;,p)gcxo z/(w. xsv 9hv-;giit has a very high thermal resistances/9. hiigp;z oxg,nv )vf;- nxs w)bc(, $R_1$ 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 pr1em y e8- mse;orel)5hic:y (oocesses: (1) ventilation around edges; (2) through the frame, particularly if it is metal; (3) througees r8(y mye;5:o)i m-1he colh 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 which of these heat losses? Explain in detail.

A piece of wood lying in the Sun absorbs more heat than a piece of shinypjfva m3 urjpq3s. 6,j(mnl. 3 metal. Yet the wood feels less hot than the metal when you pick it (q6 jnjp3 3pmr,s .vjf.mula3 up. Explain.

The Earth cools off a2y01jgimcq86 tzq dj 9t night much more quickly when the weather is clear than when cloqj1ztqg0mcy 9 dj286 iudy. Why?

An “emergency blanket” is a thin shiny (metal coated) 5hev dn0w,prjy3,xgq6t-w1uplastic foil. Explain how it can help to x0 3h6weyu rgjqwvd1-pn t5, ,keep an immobile person warm.

Explain why cities situated by the ocean tend to have less extreme temperatureswswl3* c/ cu gj,q+s0q than inland cq jsg03c+*,wu l /cwsqities at the same latitude.

  How much heat (in joules) is required to raise the temperature of 30.0 2sc; zh )4vwgwkg of water fr)wc2s4g; vhw zom 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 ie f,)jmzx nkjjx2d:0. s initially ajzx)mx jfj0 k. 2en:d,t 10.0 $^{\circ} C$ ?    $^{\circ} C$

  An average active person consumes abo2 sw9pfvobk (3ut 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 unqd5g y 5b64jv 2zh7:rk*pdtgnrbs q 1+it of heat in the British system of units. One Btu is des j rz: y6qptbb2 g5nh7*14vdgq5k+drfined as the heat needed to raise 1 lb of water by 1 F $^{\circ} $ . Show that
1Btu = 0.252kcal=1055J

  A water heater can generat9v(jlwd/awnmyajm( 09np (f p6 ,n rl.e $32,000\,kJ/h$ How much water can it heat from 15 $^{\circ} C$ to 50 $^{\circ} C$ per hour?    kg/h

  A small immersion heater is rated atba30, by0bq m0 )xy*zgvc og8z 350 W. Estimate how long it will take to heat a cup of so,bg0oz c0qym8a3bxz )g y*vb0up (assume 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 bring a c*x /iz8wf) bi1200-kg car to rest )ib*cwi fz/8 xfrom a speed of $95\,km/h$ ?    kcal

  An automobile cooling system holds 16 L of water. How mkf3v 3 ov fi1);k5yrqauch heat does it absorb if1y kriafovkv);3f3 q5 its 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 n* kr)mh(-vv6tp xu vp(g:m iw5eeded to raise 5.1 kg of the met)gw(mh v6-ipp5(m tv:xkv ur *al from 18.0$^{\circ}C $ to 31.5$^{\circ} C$ ?    $J/kg\cdot\,C^{\circ} $

  Samples of copper, aluminum, and water experience th kxzp bd 2b;f2 7rb1jxqxiu5a- d1*zn.e same temperature rise when they absorb the same rd bx*11zfuz x 2b 7a5 ipxdb;k-j2nq.amount 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 rexg ,*h yeh 4zetp806zmads 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 a 24 dhz)cgnoe11 gz)y1wj 3p,i s7:gzq6i5-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 (masstq/mvxj 5f74n;ng-)hhkxpt pau 061f = $0.4\,kg$) 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 heatehw8 ar;8xk2mtq b9xxv(t/y )qx0c)k zd 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 o gi atsd3dpcp/ 10dc 1m4-,jwuf water initially at gi 1awc1 mudp/d,s-tp04j3dc 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 cononi,+rw3 20dn f r:sdt4l;u zmtent of 75 g of candy from the following measurements. A 15-g sample of the candy is allowed to dry before putting it in a bomb calorimeter. The aluminum bomb has a mass of 0.725 kg and is placed in 2.00 kg of water contained in an aluminum calorimeter cup of mass 0.624 kg. The initial ,:s+wi drnrulto3f;z02mn4dtemperature 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 ir5nv(*ks*qszy on 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 hamac8hw9az jb/tsj j;.5mer has a speed of $6.5\,m/s$ just before it strikes a nail (Fig. 14–17) and is brought to rest. Estimate the temperature rise of a 14-g iron nail generated by 10 such hammer blows done in quick succession. Assume the nail absorbs all the energy.    $C^{\circ} $

  The heat capacity, C, of an object is defined as the amount of heat needed to ww/2t,4x8ndvqr,i/jm n0pdj raise itnpd/wxwm/,i, j4d8jr 20tv nqs 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 16.5vvvk9enifr .wh3y6 5zcb 1u3/un9em 20 kg of silver that is initially at 20$^{\circ} C$?    $ \times10^{6 }\,J$

  A 0.095-kg aluminium sphere is dropped from the roof of a 45-m-high building.+ h j-3xrkcys* m-yn9p If 65% of the thermal energy produced when it hits the ground is absorbed by the sphere, what is its +j-9*n3y-myxrp hskc temperature increase?    $C^{\circ}$

  During exercise, a person may give off 180 kcal of heat in 30 min by evaporat-6ok i 0. .a ,gccx) iwvye8adk5cg8crion of water from the skin. How much water has been losok,g c-ixvccd86a) .w08 igra. kcy 5et?    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 7p n.vv td md+d7rmbu2; j+f9gwwwd06is dropped into an insulated container of liquid nitrogenv 27b++f7uw v.t;0d6 r w9pdmdjgdmwn. 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 fro.fex i*uuc 3f9m 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 l, m;abriz54ndq v;b6 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 water over the spm).9+ne b0z k0bh ed 4yeaeb0er7ll k6an of four hours. Making the approximationrakb h4e e 0m.6n dl) k7ebe09l+0zeby 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 does go to heat, so our approximation is not far off.)    kcal

  What mass of steam at dxm+f1mn;z+g.ewt1gfn m3f( 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 mer0pvy6hy 1 9x3xhm:smwg; ny 2scury 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 atiw*ryi/oc5, :tn o*vaj3 ou)t $250\,m/s$ 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 movinx9*ielabi8pg,ih8 . v g 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 tscqft6l,iur )61d gs /hat was stopped in a doorframe apparently melted completely on i6l1 f/,g)c6 sruqs dtimpact. 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 i( y g9wy vm4c,ow;awy+s 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 conducn ajx sdz1 5+y+8uku;ction in Example 14–10, assuming that there are strong gusty winds and the external temperau+zy; kca5nj1 ux8 +sdture is -5$^{\circ} C$   $ \times10^{4 }$ W

  (a) How much power is radiated by a tungsten sphere (emidnhnlr /np/a0e57d t, ssivity $e\,=\,0.35$) 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 s0*;vysi *lezxfs d*8nkin. Suppose 200 W of heat flows by conduction from the blood capillaries beneath the skin to th xi* 8 lsefzn*;ds0*yve 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 sid0pao)) wtg kvk(h ))dke, share a 12-cm-thick brick wall. Because of a number of 100) opkd w)()k)tv0gakh -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 th yd 1di76eaql.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 length and cross-sectional are y-d3:5p-1-)pmpi mixuklxmga are attac1 m iix:x5m-)-pm3 lkdppuyg-hed end 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 the rate at which thfk)j:cf-l, fve whole Earth receives energyf,vklff :-jc ) 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 throucjivr s/u4)e tv+9 +cgrg8ab5gh a glass bulb that uagv+j s4 c+)bctrg5/8v e9rihas a radius of 3.0 cm and is 1.0 mm 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 fkx:sfbocv +5wuou.d,4/sh+ab(cs+xs*f h l/rom a 4.0-in. layer of brick and an R-19 layer of insulation, as shown in Fig. 14–19. What is the total rate of heat loss through such a wall,. s4dcbo+u* +fb5f,:wc xolu hxaks(s+ s/h/v 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 an air1 9 -lrxgjm )*qj1po2aj2qegu space, Fig. 14–20. (a) Show that the rate of heat flow through such a window by conduction is gm1jaoq9p 2 2)g-juler*gjx1 qiven 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 shoulndjf6c f7 wq:9d 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 about 0.20 kg of liquid at 2gtzq cg4;ias 0i+7n5riq/sk5$^{\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 mucoueh 5z0*-i mjh thermal energy is contained in the world’s oceans, estimate the heat liberated when a cube of me5uji* 0z-ohocean 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 tested by firing it into a fixed block of woopvh 0bwp bl5sw(3f 2,rd with a mass of 1.05 kg. The lb2b(3rv5p ,0fphws wblock and imbedded bullet together absorb all the heat generated. After thermal equilibrium has been reached, the system has a temperature rise measured as 0.020 $C^{\circ} $. Estimate the entering speed of the bullet.    m/s

  (a) Find the total power radiated into spacee0v 1n)w+hkdugdb0 i) by the Sun, assuming it to be a perfect em ug)+vhdb0nkie 01w)ditter 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, ar c9.j 8e t1ze6qpnpf8 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 ropjs9+c(cz e7slls off 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 thesze7cs+c( p9 j heat generated remains in the rock.    $C^{\circ} $

  A 2.3-kg lead ball is dropped into a 2.5-L insud*9o 9+t pgblfz(1iwr lated pail of water initially at 20.0orw(9dzpg9lib+*t1 f $^{\circ} C$. 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 with total surface ark:5eba7knqj /1;1lpy /:6 uhauvc pw sea w;su7 /hvpja5 1:6ke/c:bauyqn p1lk $1.2\,m^2$ 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 r76 llcl w0gf0oate 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 gmw2-1q dx.2n,skwjh xj :0hd the interior of the body to the surfwqdj2wd :xxkn,h. jmh2 g1s0 -ace. 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-insul. d:stu*,cr w ;jrcu+dated walls 17.5 cm thick (assume conductivity of air) and ar.ru;c, cdw j+t:*drsuea $410\,m^2$ 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+*el bfbm, ux. $220\,m/s$ 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 radiation from the yeg)5 /kfm9ox leaf y/9gmk x)of5e to 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 Earth’s atmc-k7. /+ umuo 8rkqxvzyx m(3mosphere. If its initial temperature was -.k +c k87u/q (3x mrvo-mzxmyu125$^{\circ} C$ 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 abot)i kk3xdyup l;srf8/ma+o1 tg329tk ut 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.irlaj(j-t-8 l 14–22), two people hit a soft rubber ball at a wall until they are about to drop due to dehydration and exhaustion. Assume that the ball hits the wall-rtlj-i( 8la j 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 of ice at 0 z th2f5dnw:4b$^{\circ} C$ and steam at 100$^{\circ}C $ are mixed together?

  In a cold environment, a person can lose heat by conc ihb)xw8,hs 5ef,5o xduction and radiation at a rate of about 200 W. Estimate how long it would take fo ,xoiehb5s8w)5 ,hc xfr 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” f*hz; u5o-kgq beo8;qleft in the 50-gal (185-L) water heater. This suggests that the tau*- oe ;hqz8gofkbq5;nk 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 surface of a loz,+u1k q-7g 3lvnqk60-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.    $^{\circ} C$