What happens to the work done whvn,dj6m ou*7pen a jar of orange juice is vigorously shaken?

When a hot object warms a co hc+zy5fo,lf413ozmk oler object, does temperature flow between them? Are the temperature changes of the two objects equ +,k1zl4f moh 5c3zoyfal?

(a) If two objects of different temperatures are placed in contact, will hea) 4uoa ;40hv+;vpk0t7km 3fbs iimgr xt naturally flow from the object with higher internal energy to the object with lower internal energy? (b) Is it possibl3;miaurvp0 4hf b0kk4)sigm x vot 7+;e 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 bel2fiz ozh*s xa +2i)sd:ow freezing a few times in the winter, the destruction of sensitive plants due to freezing can be reduced by waterii :h2da*zi+2)ofx ss zng them in the evening. Explain.

The specific heat of water is quite large. Expla03 m4arhz5 y 9o )mcw;jffaj mti8;b0yin why this fact makes water particularly good for heating systemsfj;fy or 08 0)jw icm9 zmh3atmba;54y (that is, hot-water radiators).

Why does water in a metal canteen stay cooler if the cloth jacket surrounding tlnm5gsact n 9; yehit;h 068;ahe c8e0ahn6 gis5mtn lth;ya; ;9canteen is kept moist?

Explain why burns caused by steam on the skin are often more severgdb aury ::wz/3e5 f(mjf-v. ne than burns caused by water at 100(eujv3f5zgaw:: f d mryb/n -. $^{\circ} C$ .

Explain why water cools (its tem0/rulccz 6am 5perature drops) when it evaporates, using the concepts of latent heat an c5a60/lmz crud internal energy.

Will potatoes cook faster if the water is boiling f;d:a+zldf h 9faster?

Does an ordinary electric fan cool the air? Why or why not? Iyi 19r k*do;kuf not, why use it?

Very high in the Earth’s atmosphere, the temperature i 7nfsamk8d*. 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 covering themsenuz4rh*n2vqi d4q 1o; lves with snow. Why would they do that?4q d4o v1hurzqn2i*n;

Why is wet sand at the2 7w. /fuylebw beach cooler to walk on than dry sand?

If you hear that an object has “high heat conteahq6 kdp8*rm6 nt,” does that mean that its temperature irh68 * kqm6daps high? Explain.

When hot-air furnaces are used to heat a house, why is it importan 0ugf5g ik55evt that there be a vent fo5g 5g5iv0kefur air to return to the furnace? What happens if this vent is blocked by a bookcase?

Ceiling fans are sometimes reversible, so that they drive the airpouh +*k.* *d1 2kxxgvlqeos *rg3y-v down in one season and pull it up in another season. Which way should you set the fan f hp2ykx ek or-v v*u*oq3x.gs+*1*g dlor summer? For winter?

Down sleeping bags and pb0w+ggl mx x5:arkas are often specified as so many inches or centimeters of loft, the actual thickness of the garment when it is fluffed up. bg :g+m0xwl5x Explain.

Microprocessor chips have a “heat sink” coc28gnhjws ;xu.h7yj61 oq z8 p1by)glued on top that looks like a series of fins. Why is it s28xn. ocsh gzbpw)y jo uc hjq6y8711;haped like that?

Sea breezes are often encountered on sum .y l+fzk+dz6-r;lxk nny days at the shore of a large body of water. Explain in lighk .f+x;-y d lrk6zmzl+t of 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 i.:5apu(tachih1 adt, 8 nvy yuqh/k/ 7s often cooler tciu ya(yndkh7ah./h, ta5vpqt 18:u/han a floor that rests directly on the ground (such as a concrete slab foundation). Explain.

A 22 $^{\circ} C$ day is warm, while a swimming pool at $22\; ^{\circ}C$ feels cool. Why?

Explain why air temperature readings are always taken with the ther 6qn0j0/ n cvyd82fgp23wbyz rmometer in the j/02yqpf v8w ryc3 2z0b ng6ndshade.

A premature baby in an incubator can be dangerously cooledbp/ :/3atoeq. dxx9o4dhh2v g even when the air temperature in the incubator is warm. p hbha4o /xo2.tdxd 3gev:q/9Explain.

Why is the liner of a thermos bordk8xpez:/xm7 o, j 7httle silvered (Fig. 14–15), and why does it have a vacuum between its two walls?je ozx8 :mh7kd/,rxp 7

Imagine you have a wall that is very wellh9 lcfj7pndk8 sf/ /d. insulated — it has a very high thermal resistance,8cdn/fkh7 /9 djsp fl. $R_1$ Now you place a window in the wall that has a relatively low R-value, $R_2$ What has happened to the overall R-value of the wall plus window, compared to $R_1$ and $R_2$ [Hint: The temperature difference across the wall is still the same everywhere.]

Heat loss occurs through windows by the following processes: (1) vent+kk,k j3w-cpxyw5b p ;ilation around edges; (2) through the frame, +k-cb ;5wkj3yp, pkxwparticularly 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) Heavy curtains reduce which of these heat losses? Explain in detail.

A piece of wood lying in :gu* upz)0bzf v1ltm8bh /xc3the Sun absorbs more heat than a piece of shiny metal. Yet the wood feels less hobp1 z*uhzcb 3 8/0l ):vmfgxtut than the metal when you pick it up. Explain.

The Earth cools off at night much more quickly when the weather is clear tha pbx7s/i6ixlu 9j9 nz.n when cloudy. W6 7jxl . ui9i9sxz/pnbhy?

An “emergency blanket” is a thin :, o(pxz2hptr shiny (metal coated) plastic foil. Explain how it can help to keep an im2rop h,zt:xp(mobile person warm.

Explain why cities situated by the ocean tend to have less e : fwco;7kmg/*ovd pd-xtreme temperatures than inland citieswk*v/ gcf7 m:oopd d;- at the same latitude.

  How much heat (in joules) isn vl4m 9uc;cx0oe*gd+m6poj + required to raise the temperature of 30.0 kg of water from 15n +m6o mpgoude4c+vl0*x9jc; $^{\circ} C$ to 95 $^{\circ} C$ ?    $ \times10^{7 }\,J$

  To what temperature will 7700 J of heat raise e jih ptdi/0q 5)/8plu3.0 kg of water that is initially iq/t8 uej0il) p h/5pdat 10.0 $^{\circ} C$ ?    $^{\circ} C$

  An average active person consumey**eq) c54h spgxz6rm s 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 ehbn0j(, 1z,7 qyjdke a unit of heat in the British system of units. One Btu is defined as the heat needed to raise 1 lz ,0eq jjnekd 1y(,7bhb of water by 1 F $^{\circ} $ . Show that
1Btu = 0.252kcal=1055J

  A water heater can gener.43ug/n6w i-ljzuj8 9iwmlfiate $32,000\,kJ/h$ How much water can it heat from 15 $^{\circ} C$ to 50 $^{\circ} C$ per hour?    kg/h

  A small immersion heater ig-gef(0*zoxi5wt ( j, ev ;ohxs rated at 350 W. Estimate how long it will take to heatjxo-o 0gtx5 efe gv;(z,ih*( w a cup of soup (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 bringy43wl lhz 6wk)h(*xrm a 1200-kg car to rest from a speed)l6 3 *y 4wzlxwhmh(rk of $95\,km/h$ ?    kcal

  An automobile cooling system holds 16 Lmpeso+r5 +fe+jogz1i 1 h) v.m of water. How much heat does it absorb if its temperature rises from 2+e .imo1zm++hpgf15rs ov)je0$^{\circ}C $ to 90$^{\circ} C$?    $ \times10^{ 6}\,J$

  What is the specific7t7o *xz gnt nif-x00y(3 puv6inkw9r heat of a metal substance if 135 kJ of heat is needed to raise 5.1 kg kx9z-tgit0( fn637nr w*nuvi xo7 yp0of the metal from 18.0$^{\circ}C $ to 31.5$^{\circ} C$ ?    $J/kg\cdot\,C^{\circ} $

  Samples of copper, axl8omw 23n q5eluminum, and water experience the same temperature rise when they absorb the same amount of heat. What is t oenmql8xw523 he ratio of their masses? [Hint: See Table 14–1.]$m_{Cu}$ : $m_{Al}$ : $m_{H_2O}$ =    :    :   

  A 35-g glass thermomet+ oykyym-olgh0p /gh*e,2 se- er reads 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 equilibriu d;gm)c35pvubm 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 ittpi ;9 j,k5c7 iyqz9(mass = $0.4\,kg$) 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 i tn7*lcnfx3*s s 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 boil6z an(ip 5ucq7f2h6s e 0.75 L of water initial 756 aehfin6sz2ucpq(ly at 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 of7s; f h1u1(rp q3ibqk6 pxxr(d candy from the following measurements. A 15-g sample of the candy is allowed(k(frpxx hid1q6 sq3 r u;1b7p 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 iro7 .axgzgux0n832 krean 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 o.khvz:y mf l58f $6.5\,m/s$ 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 neededj7/wt;y g sivw76mth c31l(vi to raisihw/v3 ltmt7(c ;1i67gyjsvwe its temperature by 1 $C^{\circ} $ . Thus, to raise the temperature by $\Delta\,T$ requires heat Q given by
$Q\,=\,C\,\Delta T$
(a) Write the heat capacity C in terms of the specific heat, c, of the material.
(b) What is the heat capacity of 1.0 kg of water?    $ \times10^{3 }\,J/C^{\circ}$
(c) Of 25 kg of water?   $ \times10^{ 5}\,J/C^{\circ}$

  How much heat is needed to melt 16.osimtn4)2eg - 50 kg of silver that is initially at 20$^{\circ} C$?    $ \times10^{6 }\,J$

  A 0.095-kg aluminium sphere is dropped fro +lnm+mvfd) 9bm the roof of a 45-m-high building. If 6)dm +vm9lfb+n 5% of the thermal energy produced when it hits the ground is absorbed by the sphere, what is its temperature increase?    $C^{\circ}$

  During exercise, a person may give off 180 kcal of heat in 30 5u frz/ptnrm:v e7sk7-q q,(sd8 yn *q -ymb,omin by evaporation of water from the skin. How much water has been lost? q(nd,, s7s -o n m/u:*q-ferbvyqy8 r k5zt7pm   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 insula622fzws+,l* uhqqqn (iaah3bted container of liquid nitrogen. How much nitrogen b6 ,n( zlhq*2awqu2iqha+3sf evaporates if it is at its boiling point of 77 K and has a latent heat of vaporization of $200\,kJ/kg$ Assume for simplicity that the specific heat of ice is a constant and is equal to its value near its melting point.    kg

  A cube of ice is taken from the freezpn +(cg6qd -roer 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 2 i+e:hlqep 8i0/b29jeue xnj 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 o wri:(nmimm* r9m5)diver the span of four hours. Making the approximation that all of the cyclist’s energy goes indini*9rm5mi w) (mmr :to 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 100b r6597uz1brsjg7 8kv f ci,tp$^{\circ} C$ 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 mercur( +2gfhednmm+8m ly,by 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 vl 8bc*8q2b e1p7wmmfat $250\,m/s$ 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 movxuzn*)p8py to0 ac8s8ing 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 inve.t*wboc1-4vsc rhq48t urv9 ustigator notes that the 8.2-g lead bullet that was stopped in a doorframe apparently melted completely on impact. Assumi9toc-uv qrt v14rbhu. wsc*84 ng 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 )n(nil7i;oda 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 co ,a sj7(1c/cvq96mpgbd5 dmk lr0t-vtnduction in Example 14–10, assuming that there are strong gusty winds and the external temperature is -5l7qmam1 r(p9/-c0dbtj,d6tk5 cv sgv$^{\circ} C$   $ \times10^{4 }$ W

  (a) How much power is radi1fhsyh1 b 4/uiated 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 skin. S 7wqbapn,2y) tii ;f-quppose 200 W of heat flows by conduction from the blood capillaries beneat bqt yn7fqp-,iia2 )w;h the skin to the body’s surface area of $1.5\,m^2$ If the temperature difference is 0.50 $C^{\circ} $ , estimate the average distance of capillaries below the skin surface.    $ \times10^{-4 }$ m

  Two rooms, each a cube 4.0 m per side, share a 12-cm-thick brick wall. Bec1ih2 1sklw0o*m q6wly ause of a number of 100-W lightbulbs il1 hslw *i62qmw0o1 kyn 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 b xtyy3b5)zmy,jjl 40llock 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 lengt7bqa+rax+hd42lolpd w,q.9cty )3ez h and cross-sectional area are attached end to end (Fig. 14–18). Th 73 .2la lc dwordxe,hpaqt+9yb )q+4ze 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, estimag;w t+xf2a na0te the rate at which the whole Earth receives f;0 2xwagn+taenergy 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 a glass buc riw o1sl,y1/lb that has a radius of 3.0 cm and is 1.0 mm thick. What is the difference in temperature between the inner and oute1i l/s ,cyw1orr surfaces of the glass?   $^{\circ}C $

  Suppose the insulating qualities of the wall of a house comg13f,rqn 8oe pe mainly from a 4.0-in. layer of brick and an R-19 layer of insulation, as shown in Fig. 14–19. What is 1 eorq8,3pgfn 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 an air sp5 lp*;rx*fqqiace, Fig. 14–20. (a) Show that the rate of heat flow through s** ;5lqqfrip xuch 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 should it take 11.0 kg of ice at)g9ndm8v 2ba m zub)r, 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 ovi6,fhk7pa ,uf 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 energy is conuyqohkj,( ns kt5+f 62tained in the world’s oceans, estimate the heat liberated when a cube of ocean water, 1 km on each side, is cooled by 1 K. (Approxt j,uhfkn5(kq s6+oy2imate the ocean water as pure water for this estimate.)    $ \times10^{ 15}\,J$

  A 15-g lead bullet is tested by firing itq fz.r,fit6 ,m:mxqk( 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 (q:z.mqk,, rfx6fim tequilibrium 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 Sun, assuug 6 j-,2q 9yi:jcngjh l,n4 1nhn*zseming it to be a perfect emitter ng:9nuqns 2h *,glj1, jhcz6y4i-ejnat $T\,=\,5500K$ 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 activitk xul),u9 *(6zithxd*i*)b 9qmozbq 1jb8iqzy, a 70-kg person may generate $200kcal/h$ Assuming that 20% of this goes into useful work and the other 80% is converted to heat, calculate the temperature rise of the body after 1.00 h if none of this heat were transferred to the environment.    $C^{\circ} $

  A 340-kg marble boulder rolls off 1g7 ;6hkf,cu k tg)xp kn.s+nsthe 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 the heat generated remangx. ;t ngpcks+),kf7s uk1 h6ins in the rock.    $C^{\circ} $

  A 2.3-kg lead ball is dropped into a 2.5-L insulated pait -cbwx00kn;dxp w0n8oa , e6nl of water initially at 20,n06t0wn nxc;0x eod8w-ap k b.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 3.5 cm thick with total surfacb,*ygyi.g2 nue area i*2 gyuyb,n.g$1.2\,m^2$ 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 metabolismmy8wqyuw/,ymr8 g +/ x 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 condmrs61 tt f) 25mnm80g9qkie gs0ly r8tucted from the interior of the body to the surface. Assume that the thickness of tissue is 4.r6m5t kg9 0r gnsl8im8y2efm)t1tq0s0 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 walls 17.5 cm thick uj 4fm7;l1y.nshgr+e*6 fqix(assume conductivity of air) and a+e4ij6x fhul .qmy7f grs1;*nrea $410\,m^2$ 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 fcgbx9px1*kl x *)ssr,o63cq ing 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 radia4+9gib-xn2gvcm ))fnrd cpi; tion from the leaf to calculate how much water must be transpired (evaporated) by the leaf per hour n bgcvp 4x )c+n;9i-)mi2fdrg to maintain a temperature of 35$^{\circ} C$.    g/h

  An iron meteorite melts when it enters the Earth’s atmosphere. If its in.z o)(*gbpsih/gop;ow:b ju .itial temperature was - woubpo;p).h.(/ bo:gj g*siz125$^{\circ} C$ 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 1.04ayr8iebevz 3v.13u b 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. o72n;paql w* eji0xw. 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 at a velocity x0w ie.j2o7a;pwl qn *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 wh6scwo ;v5+.veaao*k ven equal masses of ice at 0$^{\circ} C$ and steam at 100$^{\circ}C $ are mixed together?

  In a cold environment, a person can kn,3ji;o: iwz vn4ly. lose heat by conduction and radiation at a rate of about 200 W. Estimate how long it would take for the in nwilovk;,j: 3z.4y 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 oj pru)mv :h 9(e1hjw(the 50-gal (185-L) water heater. This suggests that the tank has emptied and refilled with water at roughly e (phovu:h 9r1)(wjjm 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 60-W ligm nke)eqi/z)cn :1y/jb8u+ azhtbulb 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.    $^{\circ} C$