What happens to the work done when a jf mck rdqxhae (+k4h0aodp92) jf e953ar of orange juice is vigorously shaken?

When a hot object warms a cooler object, does temperature flow be iu gy..ja6i q)sq)z5stween them? Are the temperature changes of the two .5)i6zs q)ys.q iag juobjects equal?

(a) If two objects of different 7z rg 5- g5je 5.*gcmtyprd,retemperatures 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 gp5r j7- rrgz*td.5g5y,ceme heat to flow even if the internal energies of the two objects are the same? Explain.

In warm regions where-dbj+ g ykq940.u-1 jgucdzqw tropical plants grow but the temperature may drop below freezing a few times in the winter, the destruction of sensitive plants due to freezing can be reduced by dqq+zgb g-9 dyu1ku40 - .jcjwwatering them in the evening. Explain.

The specific heat of water is quite large. Explain why th:-,(xgrj cqs6hf3s kh is fact makes water particularly good for heating systems (that is, hot-water radi(3hsk-sc gr6h jqx, f:ators).

Why does water in a metal canteen stay cooler if the cloth jacke543cz 8nxjr get surrounding the canteen is kepc5x48g3jr n zet moist?

Explain why burns caused by steam on the skin are often more sevh5) *(qijj kznere than burns czh i) j5kq*j(naused by water at 100 ${}^{\circ }C$ .

Explain why water cools (its temperature omhi-7zr.f ;j x ,b8*2heqfnd drops) when it evaporates, using the concepts of latent heat and internal7. ehf2zdi hn ;x*o,qr -fb8jm energy.

Will potatoes cook fastz 2 7wl7cikl .cni+nw* )bt3aper if the water is boiling faster?

Does an ordinary electric fan cool the air? Why oca+jgz 09dmq) jkq) 5nr why not? If not, why use it?

Very high in the Earth’s atq(bffj) bz 1/3qzj erw48 mt6imosphere, the temperature can be 700 ${}^{\circ }C$ . Yet an animal there would freeze to death rather than roast. Explain.

Explorers on failed Arctic expeditions have nr .r(x:mp,hwsurvived by covering themselves with snow. Why x,mnrw. rhp :(would they do that?

Why is wet sand at the beach cooler to walk on than dry sandg fj.;)p i8o00lttivk?

If you hear that an object has “high heat content,” does that mean that its th3 yenazb. tbmc )7d;.-2a ggqemperature is high? Ebzg;.thaqy)mba.c 27 e- gd n3xplain.

When hot-air furnaces are used l7lin 0avm e76u t-n zsi5+jo7to heat a house, why is it important that there be a vent for air to return to the furnt50al6 -iumvlsonj z+ 7e 77inace? What happens if this vent is blocked by a bookcase?

Ceiling fans are sometimes reversible, so that they6qj:i * x6aw c*mk cy9g(ewe(a drive the air down in one season and pull it up in another season. Which way should you set the fan for summer? For winia**qw(ej k( 9cm ac w:ye6g6xter?

Down sleeping bags and parkas are often specified as so many inches or centimet(l-gp m/i2vn4hx +gui ers of loft, the actual thickness of the garment when pni mil-gv h+ux(2/g4it is fluffed up. Explain.

Microprocessor chips have a “hev,pq acn b 9l55-lqay+at sink” glued on top that looks like a series of fins.,ylvabq c+5p 5nq9 al- Why is it shaped like that?

Sea breezes are often encountered on sunny d jzik7 ra/jic:*k8 9tc7 ts.yeays at the shore of a large body of water89tj:ei *a / .kz krct7cyijs7. Explain in light 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*6filjb50 f q(nn g4wa is often cooler than a floor that restl q4bnf65 *nia(wjf 0gs 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 tmm1l.h9s0, tvqeuxi0 aken with the thermometer in thee 0sv.lh1qxm9ut, 0mi shade.

A premature baby in an incubator can be dangerously co dt pl k wg-dm4y(ndutu8nt9j:.x:w71oled even when the air temperature .kgu p::d-wnn ( jtdlwtyu19m7dxt48in the incubator is warm. Explain.

Why is the liner of a v f*c ab j+d2h3td.*rhthermos bottle silvered (Fig. 14–15), and why does it have a vacuujbt fhc2dhva+d*r.3*m between its two walls?

Imagine you have a wall that is very well2u zi4f-)nyv9tif 1wd;hu n5 x insulated — it has a very high thermal rez1n;9)fv ud25xuif- wyhit 4 nsistance, $R_1$ 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) ve:l- ytoqk.k+vntilation around edges; (2) through the frame, particularly if it is metal; (3) through the glass panes; and (4) rad l.k:vq+o -ytkiation. (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 lyingk*+h2r mrj wd, in the Sun absorbs more heat than a piece of shiny metal. Yet the wood feels less hot than the metaljw mk 2h*,drr+ when you pick it up. Explain.

The Earth cools off at night much more quickly when the weatherw.5u scp2f 8i*w 2kogh is clear than when cloudy. 2gohf*.cspi w2ukw58 Why?

An “emergency blanket” 83 ft*f xbhb lami (w6(fw+be9is a thin shiny (metal coated) plastic foil. Explain how it can help to keep an immobile6h af(bbe8b(lm 3 x+wfw ti9f* person warm.

Explain why cities situated by the ocean tend to have lesy t3q0pi p5h:gs extreme temperatures than inland cities at the same latitude.q g5p3y ht:pi0

  How much heat (in joules) is requireppdm6he+mni5t. e0 z ,d to raise the temperature of 30.0 kg of water en0m ,pzp 6t i+d.eh5mfrom 15 ${}^{\circ }C$ to 95 ${}^{\circ }C$ ?    $\times {10}^{7}J$

  To what temperature will 7700 J of41p8yei e b+re heat raise 3.0 kg of water that is initially abpeery +ie 148t 10.0 ${}^{\circ }C$ ?    ${}^{\circ }C$

  An average active person consumergwila4k:6 : ydrn 1:os about 2500 Cal a day.
(a) What is this in joules?   $\times {10}^{7}J$
(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 in the Br2;nd xefu7 fe7z ,+at6t7dqpf itish system of units. One Btu is defined as thf2uafn dz7f7exe tdpt76q +; ,e heat needed to raise 1 lb of water by 1 F ${}^{\circ }$ . Show that
1Btu = 0.252kcal=1055J

  A water heater can gene d bkghxgiluz2150k +.m.t7hgrate $32,000kJ/h$ How much water can it heat from 15 ${}^{\circ }C$ to 50 ${}^{\circ }C$ per hour?    kg/h

  A small immersion her5n vz yh, xb,mjxu/2;ater is rated at 350 W. Estimate how long it will take to heat a cup of soup (assume this isxh25vn , r/x;z,umyjb 250 mL of water) from 20${}^{\circ }C$ to 60${}^{\circ }C$ .    min

  How many kilocalories) nykm9 ib/9pdajc6j; are generated when the brakes are used to bring a 1200-kg car to rest from a spe /bkm9jp9cyj na6;d )ied of $95km/h$ ?    kcal

  An automobile cooling system holds 16 L of water. How much za 6p/s(h)1 im:ew dy+ *pocqdheat does it absorb if its temperac d :1h)epqmpz( woysi/+*d 6ature rises from 20${}^{\circ }C$ to 90${}^{\circ }C$?    $\times {10}^{6}J$

  What is the specific heat of a j r+jhgkvh3,ju 3r/4a/bag7s metal substance if 135 kJ of heat is needed to raise 5.1 kg of the hj/asjagg,r +u3/37rk 4v jhbmetal from 18.0${}^{\circ }C$ to 31.5${}^{\circ }C$ ?    $J/kg\cdot C^{\circ }$

  Samples of copper, aluminum, and water exw7ypoz/kj. a z-7q t,1v-av zxperience the same temperature rise when they absorzz 7w xzv /.7at1pv-,k- oayjqb the same amount of heat. What is the ratio of their masses? [Hint: See Table 14–1.]$m_{Cu}$ : $m_{Al}$ : $m_{H_{2}O}$ =    :    :   

  A 35-g glass thermomet cv-iqfbjee0a,y96*v3tt6t2 x rr u0 ver 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?$T_{i{H}_{2}O}$ =    ${}^{\circ }C$

  What will be the equilibrium temperature when y -pbyai .bnrju;6* 5ua 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 (mass oo f9 wsixl e5vpf4i961iv26 nr, ub:n= $0.4kg$) 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 sunyx :r,tv3 mid.,ne)/ .vbcir h*e6erbstance is 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;,cxu:0 xgzbqe f5 g9j coffeepot to bring to a boil 0.75 L of water initially at ec0z9g;bx, 5xfgqj:u8.0${}^{\circ }C$? Assume that the part of the pot which is heated with the water is made of 360 g of aluminum, and that no water boils away. $\approx$    min (Round to the nearest integer)

  Estimate the Calorie content of 75 g of candy from the following m;qq1asf pp9zqq .f -4teasurements. 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 placzfa; 1s. p-qpq4 tqqf9ed 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 ironaspn* q3dlzai6s +2e, 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 of-w9bgwv nh2/a7qmnmn5 8tu2w $6.5m/s$ 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 heqsdx d48eoxx :n(c1*sat needed to raise iexq8 x (1ossd*4:dcxn ts temperature by 1 $C^{\circ }$ . Thus, to raise the temperature by $\mathrm{\Delta }T$ requires heat Q given by
$Q=C\mathrm{\Delta }T$
(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?    $\times {10}^{3}J/C^{\circ }$
(c) Of 25 kg of water?   $\times {10}^{5}J/C^{\circ }$

  How much heat is needed to melt 16.50 kg ozj)bs / qqjc;1 4ck*gsf silver that is initially at 20${}^{\circ }C$?    $\times {10}^{6}J$

  A 0.095-kg aluminium sphere is dropped fro 4t)lkfb wnz )4nxge./m the roof of a 45-m-high building. If 65% of the thermal energy produced when it hits the ground is a)kx)44z . wlnfbetgn/ bsorbed by the sphere, what is its temperature increase?    $C^{\circ }$

  During exercise, a person may give off 180 kcalga g)t7 i7i-tuqx:1 q 1fn3mhn of heat in 30 min by evaporation of water from the skin. How much water haat3 q : h- 7xnf)t71qumig1ngis been lost?    kg

  If $2.80\times {10}^{5}J$ 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 insulated container 6zrg2l ,na mizu*f3;dof liquid nzf*n63rl dzi ; ,uma2gitrogen. How much nitrogen evaporates if it is at its boiling point of 77 K and has a latent heat of vaporization of $200kJ/kg$ 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 takenr4n+) njd(ut g from 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?    $\times {10}^{-3}$ kg

  An iron boiler of mass 230 kg contains 830 kg of water at 1piwuq 8h7sa/e /5etj:8${}^{\circ }C$. A heater supplies energy at the rate of $52,000kJ/h$ 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 frd4em( pc5g*;xw yq +x-ca sl6 0ol1e8.0 L of water over the span of four hours. Making the approximation that all of the cyclist’s energy goes into evaporating this water as c1(d; exrfo4m5xy6qla 0lspg we+c-* 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 6n dc;v;4.ty u ( zie6.wuhn3r pl) v9svdme(o100${}^{\circ }C$ 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 m tv-/gbd srf(y5or6b )ercury is $138J/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${}^{\circ }C$ .    $\times {10}^4$ J/kg

  A 70-g bullet traveli pfelsp3en1s 2r2 eud2-j o.w*ng at $250m/s$ 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 mov)w-:r/wcjvu sn cj:,. x5d,ss2 rz onving at $6.4m/s$ 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 forensi+d p0q 6/ztcvwc investigator notes that the 8.2-g lead bullet that was stopped in a doorframe apparently melted completely on impact. Assuming the bullet wa t0+qv6zw p/cds 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 is kept an ; j-cda fbi.trn2x25t 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 14nmyhy7 r27k v4–10, assuming that there are stron2rnk 477vhyym g gusty winds and the external temperature is -5${}^{\circ }C$   $\times {10}^4$ W

  (a) How much power is radiated by a tungsten sphere (emissiiazo5.jnb xox8.v. 7b7 (72pbtbqh esvity $e=0.35$) 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 20 v 8/lng1y/hmdg 3u:ot)eanf4 0 W of heat flows by conduction from the blood capillg 3u4eh/ ) n got1n/dy8mfavl:aries beneath the skin to the body’s surface area of $1.5m^2$ If the temperature difference is 0.50 $C^{\circ }$ , estimate the average distance of capillaries below the skin surface.    $\times {10}^{-4}$ m

  Two rooms, each a cube 4.0 m per side, share a 12-cm- byfk)g x;jyrtp ( y;09ur.4pxjt.a 4lthick brick wall. Because of a number of 100-W ligh4a x;40;y(b j.k ru.j trtfl9ypxpy)gtbulbs in one room, the air is at 30${}^{\circ }C$, while in the other room it is at 10${}^{\circ }C$. How many of the 100-W bulbs are needed to maintain the temperature difference across the wall?    bulbs

  How long does it take the Sun to melt a:e. fnl:e8/ qgees, ec block of ice at 0${}^{\circ }C$ with a flat horizontal area $1.0m^2$ 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-section lev*(gc w4.hed ,ni1jfoq(lc gzl675al area are attached end to end (, dligcog 7ze1lc5jl.e (qv(46w* fhnFig. 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 the w* 20p4mf8 1 rfa+guhuyt6 rexlhole Earth receives energy from the Sunu1*rmrftgxhf2648lap u 0+ye .    $\times {10}^{17}$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 gene9.t u b)sm5zlsrates 95 W of heat, which is dissipated through a glass bulb that has a radius of 3.0 cm and is 1.0 mm thick. What is the difference in temperature between the inner and outer surfab .u )5sl9tszmces of the glass?   ${}^{\circ }C$

  Suppose the insulating qualities of the wall of a house come mai ggr8nsolj ;*6nly from a 4.0-in. layer of brick and an R-19 layer of insulation, as shown in Fig. 14–19. 86ln ojr sg*;gWhat is the total rate of heat loss through such a wall, if its total area is $240f{t}^2$ 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 spz3isvv, 7p8mm :ynjvu7umz 57ace, Fig. 14–20. (a) Show that the rate of heat flow through such a window by conducts73mvm iuzm7yju5:n8vp,vz 7 ion 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 iil;a l (r5x13k/smoqcce at 0${}^{\circ }C$ to melt when it is placed in a carefully sealed Styrofoam ice chest of dimensions $25cm\times 35cm\times 55cm$ 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${}^{\circ }C$.    $\times {10}^4$s

  A soft-drink can contains abpr.a*avs l6/f out 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 $30MJ/kg$ when it is burned, how much coal would be needed to heat a house that requires $2.0\times {10}^{5}MJ$ 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 ck:5s5 ud: qcjcontained 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. (Approximate the ocean water as pure water for this estimccj:5u k5:sqdate.)    $\times {10}^{15}J$

  A 15-g lead bullet is tested by firing ij0q gdcd 1vk)/t into a fixed block of wood with a mass of 1.05 kg. The block and imbedded bullet togj q/k1)0 dgdvcether 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 .;z :fyrdo v-+ntt gd+radiated into space by the Sun, assuming it to be a perfect emitter at +dt.zdvn:y-r t; fo+g$T=5500K$ The Sun’s radius is $7.0\times {10}^{8}m$    $\times {10}^{26}W$
(b) From this, determine the power per unit area arriving at the Earth, $1.5\times {10}^{11}m$ away (Fig. 14–21).    $\times {10}^{3}W/m^2$

  During light activity, a 70-k mns8+/n6 k5fuvvr 8rfjp.:vgg 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 the top of cu,sus 5ec-irha6 c3 +a cliff and falls a vertical height of 140 m before striking the ground. Estimate the temperature rise of the rocc6sreh u-as c+ 35i,cuk 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 udgv(-5p (itypail of water initially at 20.v- (di5(pgt uy0${}^{\circ }C$. 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 dowrd, aam4c. *+c.u1vtqhra w4. b+kx fun jacket 3.5 cm thick with total surface area hv 1rc+.*+.cq4u.dwa uakma,rb fx4t $1.2m^2$ 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 metaboliskdw:zzbb4mn *h91 cm4 m rate of about $950kcal/h$ 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 the. v .wbf*e*:t-zpsoyj; v0js l body to the surfle.j:f z s*v0to y;.vw spj*b-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 $1.5m^2$ 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 (assumekp r*.bc87i wz conductivity of air) and area*bi7crz.wpk8 $410m^2$ a roof of wood 6.5 cm thick and area $280m^2$ and uncovered windows 0.65 cm thick and total area $33m^2$
(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${}^{\circ }C$    $\times {10}^5$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 $750m^3$    $\times {10}^8$J
(c) If natural gas costs 0.080 dollars per kilogram and its heat of combustion is $5.4\times {10}^{7}J/kg$ 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 $0.24kcal/kg$$\cdot C$.    dollars

  A 15-g lead bullet traveling(suz k7vv9y0(o6 rv rf at $220m/s$ passes through a thin wall and emerges at a speed of $160m/s$ 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 $40c{m}^2$ and mass $4.5\times {10}^{-4}kg$ directly faces the Sun on a clear day. The leaf has an emissivity of 0.85 and a specific heat of $0.80kcal/kg\cdot K$.
(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 Pr jcltxx:f9 w 0(q6hzbiu--jn2oblem 58, take into account radiation from the leaf to calculate how much water must be transpired (evaporated) by the leaf per hour to maintain a temperatuwxj fn i-(2l hb69zq 0x-tj:cure of 35${}^{\circ }C$.    g/h

  An iron meteorite melts when it enters the:*,o z1a, jv7h;g r)xplflelp Earth’s atmosphere. If its initial temp7z; ,1 hllxa,gl*v :)eprp fojerature was -125${}^{\circ }C$ outside of Earth’s atmosphere, calculate the minimum velocity the meteorite must have had before it entered Earth’s atmosphere.    m/s

  The temperature withinhrxdi*mt +9etrd*o : ) the Earth’s crust increases about 1.0 C${}^{\circ }$ for each 30 m of depth. The thermal conductivity of the crust is $0.80W/C^{\circ }\cdot m$
(a) Determine the heat transferred from the interior to the surface for the entire Earth in 1 day.    $\times {10}^{18}J$
(b) Compare this heat to the amount of energy incident on the Earth in 1 day due to radiation from the Sun.$Q_{Sun}$ =    $\times {10}^4{Q}_{interior}$

  In a typical game of squash (Fig. 14–22), two ppva c-r 1yk* zl2-j7 flu+cuc(eople hit a soft rubber ball at a wall until 1 rlu2cl z-(-f*y7 auj+cvcp kthey are about to drop due to dehydration and exhaustion. Assume that the ball hits the wall at a velocity of $22m/s$ and bounces back with a velocity of $12m/s$ 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 $1200J/kg$$\cdot C$)    $C^{\circ }$

What will be the final result 9v5w ho ;9xm:ip+5cb/)dicl hs) uuu bwhen equal masses of ice at 0${}^{\circ }C$ and steam at 100${}^{\circ }C$ are mixed together?

  In a cold environment, a pers.6w++kzxxr yo on can lose heat by conduction and radiation at a rate of about 200 W. Estim6 +oryxx .z+kwate how long 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 insp1odx.( k 9, aykhul3 the 50-gal (185-L) water heater. This suggests that the tank has emptied and refilled with w.kk9 p3 1ya(suh d,oxlater 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 60-W -y5 x-yzpbcra.f u2x: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.    ${}^{\circ }C$