What happens to the work done when t(cw tr( v+l:k47d+i o4rzfoca jar of orange juice is vigorously shaken?

When a hot object warms a cooler object, does temperature flow bev2glf(q sf8z0 .h6f vovvr49etween them? Are the temperavqfohvzvfl2 ( 86 g4sv0.9f reture changes of the two objects equal?

(a) If two objects of different temperatures are placed in contact, will heaecwhei.ssvhf-l o8 u 4 n,0:f(t naturally flow from the object with higher internal energy to the ,ne iffl. os0:sh( u8-wv4eh cobject 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 temperature may drop below fru4 nqix8 gf2z3hna7t8eezing a few times in the winter, the destruction of sensitive plants due aufhxng8q 2z 8n734tito freezing can be reduced by watering them in the evening. Explain.

The specific heat of water is quite large. Explain why thig w0vy,e9d3/n6 vx x:m*yiuqo s fact makes water particularly good for heating systems (that is, hot-water q9*: ,nyx6ve wvi m/y0uxd g3oradiators).

Why does water in a metal c((kqb9pc oie( anteen stay cooler if the cloth jacket surrounding the cant k(b9oc pi((eqeen is kept moist?

Explain why burns caused by steam on the ski ale 4j 5rgxs xg0p5,n9y,yu 9ec(9p ur+0zzwin are often more severe than burns caused e5 i9crsr ul9,0p,+j5w0ayu4gpg(ezzx y 9xn by water at 100 $^{\circ} C$ .

Explain why water cools (its temperature drops) when it evaporates, usiliu0g/ s o2hl+ng the concepts of latent heat and internal ene0ls/+lo2 ihgu rgy.

Will potatoes cook faster if the water is boiling fastein r xag ie*7e57x,xs(r?

Does an ordinary electric fan cool the air? Whypj20hcg , 9rro or why not? If not, why use it?

Very high in the Earth’s atmospheror)x7q 46fkk a l2f8yua) v*xae, the temperature can be 700 $^{\circ} C$ . Yet an animal there would freeze to death rather than roast. Explain.

Explorers on failed Arct /ioo3xa9 8rvvic expeditions have survived by covering themselves with snow. Why would they do th i a98v/xroo3vat?

Why is wet sand at the beag/qbqe4 540dz:i hrau ch cooler to walk on than dry sand?

If you hear that an objeaef3d;g*m +s; b,q kxyct has “high heat content,” does that mean that its temperature is high? Explai*eq,ks; f g 3xdy+bm;an.

When hot-air furnaces are used to heat a houfo6jhtmr28ml zh9n3 3se, why is it important that there be a vent for air to return to the furnn ml683h23 ofj mhrz9tace? What happens if this vent is blocked by a bookcase?

Ceiling fans are sometimes reversible, so that t*0w2deh wozyp- l -k4xh*n2qthey drive the air down in one season and pull it up in another season. Which way should you set the fan fyw-x2nq4zdwo*kh etlp0 - h* 2or summer? For winter?

Down sleeping bags and parkas are often specified as so many inches or centimep+ib :)ai5lehlz7, r nters of loft, the ac) ,e+lzhirp:l 7abn 5itual thickness of the garment when it is fluffed up. Explain.

Microprocessor chips have a “heat sink” glued on top that gi4i72ivdo 0u looks like a series of fins. Why is it shaped lik udg20ivi7 4oie that?

Sea breezes are often encountered on sunny days at the shore of a large boz1w) )rgqd l +jg*s0dvdy of water. Explain in light of the fact that the temperature of the land rises more rapidly than that of the *ws 0 dlqgg)zr vd1+j)nearby water.

The floor of a house on a foundation under wha*4 x8iz fxakf8q-7 b43bll,y /6d wr kgkd;pjich the air can flow is often cooler than a floor that rests directly on the ground (such as a concrete slab foundationk /l*4klb z 8pdxw-j8qffa6 4ka7;xi3,drbgy ). 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 thermome,pvlanptg0iko)83g+ 1 fn ) xnter in the sv )lo8gtgp x+n3 1p,0fnn aik)hade.

A premature baby in l19ihqtqg- g0:f6x 8i p bew,man incubator can be dangerously cooled even when the air temperature in the incubator g6ii xpbfew 1ltm gq,089 :-hqis warm. Explain.

Why is the liner of a thermos bottle silve*cjh hk0 d yzk0.dvz5j b8k;/jred (Fig. 14–15), and why does it have a vacuum between its t8zc /.h jkv0*dzdkj05b y;hkjwo walls?

Imagine you have a wall that is very well insulated — it has a very high imtzw d00 hp3qujpz(4*9 4axzthermal re3qu 0mhj x( i*d 0zpt4azwp49zsistance, $R_1$ 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 processl d:rc n-2qcsnlc8942am1nmphj gv31es: (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): conduction, convection, or radiation? (b) Heavyn 9a s2pc8j4n 3gd r2qcnlh 1-mvc:m1l curtains reduce which of these heat losses? Explain in detail.

A piece of wood lying in the Sun absorbs more heat theivpk.eo2w r*hx (k)4 uyme* +an a piece of shiny metal. Yet the wood fe*eumi ohe*v+w 4kexk(py2) .r els less hot than the metal when you pick it up. Explain.

The Earth cools off at night much more quickly when tf.yj zc*:/h mfyr-a8g ;crgk uka t+8,he weather is clear than when cloudy8;g: rtyurk+jc/-ckya8z h, a f.mf*g. Why?

An “emergency blanket” is a thin shiny (metal coated) plastic foil. Explain hz49r6:pr yyli-7yqz how it can help rryq79l zz yh -6piy:4to keep an immobile person warm.

Explain why cities situated by the ocean tej n4qq9r/kxa2c ir*eq-9br .xnd to have less extreme temperatures than inlan -q x9/r nqrx*ke cbq94rjai.2d cities at the same latitude.

  How much heat (in joules) is required to raise the temperature oes /mu i*86l-uk 5p2snz zq(cbf 30.0 kg of water fuis*(6/k sz u-nb58l qc2 ezmprom 15 $^{\circ} C$ to 95 $^{\circ} C$ ?    $ \times10^{7 }\,J$

  To what temperature wik.gb1 b)j+c3fy n. dzj rr r+r3-d0pdrll 7700 J of heat raise 3.0 kg of water that is initially at 10.0b.r p drjjdrr1r0c33.+z+y g)dk n-bf $^{\circ} C$ ?    $^{\circ} C$

  An average active perstu g. io/)hd0ton 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 of heat ;//f+qozq 8iu2j dc uhin the British system of units. One Btu is defined as the heat needeq2//uudohzf ;ij 8cq+d to raise 1 lb of water by 1 F $^{\circ} $ . Show that
1Btu = 0.252kcal=1055J

  A water heater can ge b2ahe 3ph0pjeu/spcmnvab, kc 8;f.2l87 a. qnerate $32,000\,kJ/h$ How much water can it heat from 15 $^{\circ} C$ to 50 $^{\circ} C$ per hour?    kg/h

  A small immersion heater is rated at 350 W. Estimate how long it will take to he2lv hzu;ljcr bl70 /m;at a cup of soup (assume this i l;jl02uz7m/vbh clr; s 250 mL of water) from 20$^{\circ} C$ to 60$^{\circ} C$ .    min

  How many kilocalories are generate qriebjnkglx.f /)i j4.47mv0d when the brakes are used to bring a 1200-kg car tjx.vfib/)r4e4q n 0 jmli. k7go rest from a speed of $95\,km/h$ ?    kcal

  An automobile cooling system holds 16 Li) 96jor kfcc) of water. How much heat does it absorb ifk9i rcj6o)fc ) 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 nuq+f q rv5dd7lv/1b)iw7nj:wi(pj 2 si;s b(is needed to raise 5.1 snlwv(i+w: (2jisunb)b /;vdqprid7j15f7 qkg of the metal from 18.0$^{\circ}C $ to 31.5$^{\circ} C$ ?    $J/kg\cdot\,C^{\circ} $

  Samples of copper, aluminum, and water experience the same temperature rise whe3ts/ys 0z1d w.a:cajpn they absorb the s1 /. st3 0wazpsy:djcaame 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 readn+kv /y0z4c1xb, yssds 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 2458lx , d/*;ns-b:s kvt9vjajgi-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 (mlz-iw lf, ca6hnw+ u4/ass = $0.4\,kg$) 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 in9up.w,r +6.aw fq,k )muy1m.m mbqhto 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 azi m,9vmc56scoffeepot to bring to a boil 0.75 L of water initially at 86amz5vm c 9is,.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 conteng,)gl q90t u zkporqfpcd- 019t of 75 g of candy from the following measurements. A 15-g sample of t0rfkg1dt)cqu9oq z gp0-l,9p he candy is allowed to dry before putting it in a bomb calorimeter. The aluminum bomb has a mass of 0.725 kg and is placed in 2.00 kg of water contained in an aluminum calorimeter cup of mass 0.624 kg. The initial temperature of the mixture is 15.0$^{\circ}C $ , and its temperature after ignition is 53.5$^{\circ} C$ .    Cal

  When a 290-g piece of iro+w+/lu rfmt -pn 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 spes6n3 +4 zv,8*ohvfr h )fcb*isxx;xa ied 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 amoua;cj47 h55+qy-l h)p,ryfxornt6e vont of heat needed to raise its temao ej -xthv5n)fp+4yyroh;5 7q, cl 6rperature 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.,t 5jq7nvr1(aus hw he nw95x23d6o nd50 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 bu j-dy7l9i ;vdeilding. If 65% of the thermal energy produced when it hits the ground is absorbed by the sphere, what is its temperature ince; jd9d-yvi 7lrease?    $C^{\circ}$

  During exercise, a person may give off 1m.bc 5qkdtrm1l n ;.0y80 kcal of heat in 30 min by evaporation of water from the skin. How much wamnmbd .;5kqy1 c.lr0t ter 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 insul5rnp.fr-vh ) h f3eyepw 8yh+y342 oofated container of liquid nitrogen. How much nitrogen evaporates if it is at its boiling point ofehr+2.5 3yy hn-o8pf3pyevff4h )wro 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;-5nxsk: xm zmjmy 22i freezer at -8.5 $^{\circ} C$ and placed in a 95-g aluminum calorimeter filled with 310 g of water at room temperature of 20.0$^{\circ} C$. The final situation is observed to be all water at 17.0$^{\circ} C$. What was the mass of the ice cube?    $ \times10^{-3 }$ kg

  An iron boiler of mass 230 kg contains 830 kg of water 3v;lkt4q/dcqa)k3 w t 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 tdeuy 9k)*0 + aqjwkb rmzd9a*5he 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*zray wd9 amkj9+uqbd*e 5) 0k 20%, most of the energy consumed does go to heat, so our approximation is not far off.)    kcal

  What mass of steam at 1zk n //efqx3,xpz *v1i00$^{\circ} C$ 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 ofhr-;sf mv f d64qx/nq+ mercury 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 travelihe 7b(h.3ubf xng 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 moving atrs xc;0x210 * up+axelqmslqi7/ 1gmj $6.4\,m/s$ 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 forfa(kv p)uj8 e-ensic investigator notes that the 8.2-g lead bullet that was stopped in a doorframe apparently melte p(e8jku)-vf ad completely on impact. Assuming the bullet was fired at room temperature (20$^{\circ} C$ ), what does the investigator calculate as the minimum muzzle velocity of the gun?    m/s

  One end of a 33-cm-long aluminum rod with a diameter of 2.jj+ ;qxa3 ;aozcj9sekk-- va00 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 Examstm4 0,wx5;rlv 6imi jple 14–10, assuming that the5s 6rmlt;, mwxvi4i j0re are strong gusty winds and the external temperature is -5$^{\circ} C$   $ \times10^{4 }$ W

  (a) How much power is radiated by a tungsten sph mt7n23 i0ls8g 6cwcdhere (emissivity $e\,=\,0.35$) of radius 22 cm at a temperature of 25$^{\circ} C$ ?    W
(b) If the sphere is enclosed in a room whose walls are kept at -5$^{\circ} C$ what is the net flow rate of energy out of the sphere?    W

  Heat conduction to skin. Suppose 200 W of heat flows b1ox g:wv0 )7obwpw: u+ qtnlf1y conduction from the blood capillaries beneath the skin to the body’s surfacepf vot woln0+w u7:gbq11x): w 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 peo* /hyzse6eeur7 .y;er side, share a 12-cm-thick brick wall. Because of a number of 100-W lightbulbs in one room, the ar yy h;ue .6oe/ees*7zir 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 4jwg ql8e.6h8l2 nzgua 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-sectioj*q8+y d xf(y k:l(ozyg8n vb1nal area are attached endb*o1 yn:+yflxyq(8 8 (jdkgz v 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 ag i-.nbn-;6emyelq 2wt which the whole Earth receives ;.n 2ewy6nmqib--g leenergy 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 througvtf5 ma4hbugat 9 :(a845ddls4d h ym8h a glass bulb tasdm( 4tb:5m 4gva ydt9 fld8 h4uah58hat has 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 qualb6 2cvdz4/ovp ities 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 the total rate of heat loss through such a wall, if 24/bvc pd6zov 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 sn(:rfuy(u ;+kcpz4pnt4y f i5 eparated by an air space, Fig. 14–20. (a) Show that the rate of heat flow through such a window by conduction+ypnzf4yctuf:u kir4(p(5n; 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 uy/. csp3u4fbz6f8(3 5i q nzs45r eql;lhbvzshould 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 xkugl w-5 ;+djl,lik0 kg of liquid at 5$^{\circ}C $. Drinking this liquid can actually consume some of the fat in the body, since energy is needed to warm the water to body temperature (37$^{\circ} C$). How many food Calories should the drink have so that it is in perfect balance with the heat needed to warm the liquid?    C

  If coal gives off $30\,MJ/kg$ when it is burned, how much coal would be needed to heat a house that requires $ 2.0\times10^{5 }\,MJ$ for the whole winter? Assume that 30% of the heat is lost up the chimney.    kg

  To get an idea of how much thermal enht *ijv7dfaz0e)ucu+ rr6:x4 ergy is contained in the world’s oceans, estimate the heat liberated when a cube of ocean water, 1 km on each side, is cooled by 1 Kvia7:e+06 uz rfr j4x*tdc)u h. (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 wood wil+ a(,uh 1uepi4 obqe9th a mass of 1.05 kg. The block and imbedded bullet together absorb all the heat generated. After thermal equilibrium has been reeu +oblae 1,p(4uhi q9ached, 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 it to be a pe/8ek7kun vdip jwe vmq:/(qy oe276q, rfect(/ d/ye,qq m6ev ku78 7nqwi:ejo2vkp 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 3:kqlc;lcia +(miv 2 imay 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 falls a verticax3orq wt zr/z9+qz) ,ol height of w ,zoqr3zzrtq/ o+x9) 140 m 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 is dropped into a 2.5-L insulated pail of water i+-qa+x1 mcz 6/nrf wrh*tqdl7nitially at fwq-*d61c/x rlh qnmrz+a+ t720.0$^{\circ} C$. 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 gooseain7jj9erh r9lt 7leg )69wu- down jacket 3.5 cm thick with total surface areu9l-ng67)9jr w r 7ehi9ljae ta $1.2\,m^2$ 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 ocb0v)/ixbd3i:l 2mv1u d*o nmf about $950\,kcal/h$ during a race. If the runner has a mass of 55 kg, estimate how much water she would lose to evaporation from the skin for a race that lasts 2.5 h.    kg

  Estimate the rate at which heat can be conducted from the interior of qfnjg-rd1 d;w ov*)+l2,bb suthe body to the surface. Assume that the thickness of tissue is 4.0 cm, that thdj q w bb)lf2vs+dno, ;ur1g*-e 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 aqa19ti,1 ejmare1 eqa9 mi1j,ata $410\,m^2$ 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 travel ygr :8z;xrndoj re cyp/9.*-ling 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 radiation frybywb- 1hbx bf, :brp8v4( 6wqom the leaf to calculate how mu x,8w-(b6wpby qh:y 41rbfbbvch 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 t +tf x .9t) zuy)i7-wda6zdwythe Earth’s atmosphere. If its initial temperature was -atwz . dwy6xi yf)u)td79 z-+t125$^{\circ} C$ 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 about 1dyu 7rp-z5bmrf:, )rub li2 y0.0 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 peopl g ix u4(f4qb1pm2riq a9su80ne hit a soft rubber ball at a wall until they are about to drop due to dehydration and exhaustion. Assume tha9 a 8qq ubx1(i44us0pmi2fnrgt 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 final result when equakbl3l +oqe3z -l masses of ice at 0$^{\circ} C$ and steam at 100$^{\circ}C $ are mixed together?

  In a cold environment, a persj lp.r2pi1(cuon can lose heat by conduction and radiation at a rate of about 200 W. Estimate how long it would take for the body temperature to drop from 36.6plrji .1u2(c p$^{\circ} C$ 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” lef fwwgm-vdbl 4.glu2-0t in the 50-gal (185-L) water heulb.d-glgf 2v -4w mw0ater. 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 surface of a 6rpp ty+9 r3+fl0-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.    $^{\circ} C$