What happens to the work done when a jar of o*sv r0d34fu8d7 ptrskrange juice is vigorously shaken?

When a hot object warms a cooler object, does temperature flow between them? Ahdo)+l +5qfhs0y(0 ly:hhs xr re the temperature changes of the two object+llhs0r5ydhshq0x(o+ ) hfy: s equal?

(a) If two objects of different temperatures are placed innx0tc.*1an2h n ri;xaz ,(q ye contact, will heat naturally flow from the object with higher internal energy to the object with lower internal ene z n0;e 1yxrnhqitxn2a(a.,*c rgy? (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 tropicaqp iajh 2u47j(l 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 7pjhqaj4(iu2reduced by watering them in the evening. Explain.

The specific heat of water is quite large. Explain why this fact mavm2qmos 3-rm taqx ms11s)/mxz- tm9 4kes water particularly good for heating systems (th3-q92 mrs xo s4m1/sav)xm tm1qz-mmt at is, hot-water radiators).

Why does water in a metal canteen stay co e i8vkq/b2kg5rtvr35ly,mb2oler if the cloth jacket surrounding the canteen is k yb/emt8k5 2gv3,kbi5r2qv rlept moist?

Explain why burns caused+kgqu61xn 2r q 05x*wp oamj+c by steam on the skin are often more severe than burns caused by wac1 x 6j+x o0mar2kpqqn+5uwg *ter at 100 $^{\circ} C$ .

Explain why water cools (its temperature drops) when it evaporates, using thefr6 .vq3e8dck pahj7g :tsw;i9xmy, - cowf:xeak3qr-yj7d69 h cv. ; t8 ip,gmsncepts of latent heat and internal energy.

Will potatoes cook fast8nw(j, f rix7zer if the water is boiling faster?

Does an ordinary electric fan cool the air? Why or why not? If notn*o4cuk 43 wihw64ob h, why use it?

Very high in the Earth’s atmosphere, the temperature can bk9rm tt;lm i3hzb6 :8ke 700 $^{\circ} C$ . Yet an animal there would freeze to death rather than roast. Explain.

Explorers on failed Arctic expeditions have survived by covering themsem-kog7pw* dogfj*:oe9 7/i z flves withmdgzog ef *7w9poo ij*k/f -7: snow. Why would they do that?

Why is wet sand at the beach cooler to walk on than dry sand?w55 aj dd2t7vo

If you hear that an object has “q 7 ((zycnmxdfx:r*8dhigh heat content,” does that mean that its temperature is high?*fyr7c(: 8d zmqxxnd( Explain.

When hot-air furnaces are used to heae*efygf q o, 5ih07v;qt a house, why is it important that there be a vent for air to return to the furnace? What happens if this ve;50ehfv ,ye7oqfiqg*nt is blocked by a bookcase?

Ceiling fans are sometimes reversible a0dh6f ,lzt *epo93in, so that they drive the air down in one season and pull it up in another season. Which way should you6fno 9zi he p30d,atl* set the fan for summer? For winter?

Down sleeping bags anop h.kaj g1t1m +fc*,kd parkas are often specified as so many inches or centimeters of loft, the actumf11+.,akc t ho*gjk pal thickness of the garment when it is fluffed up. Explain.

Microprocessor chips have a “heat sink” gl*ovv jo/ z;38xagnf0mued on top that looks like a series of fins. Why is it shaped likez ; omf/a0*jgo3xvv8n that?

Sea breezes are often encountered on sunny days at the shore of ad2nrob g.fim*d).u)o6vsch 2 large body of water. Explain in light of the fact that the temperatur6.so)bd 2)f*m r uhonvi .c2dge 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 often3z*c j bwj8r*d cooler than a floor that rests directly on the ground (such as a concrete slab foun r c3jjz8b*w*ddation). 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 thermometer in thmw05ux1k7 b4kc-im;al j wpp*e shaci ;47 x kbj0awpmp1muwk-l5*de.

A premature baby in an+c ynjq; 3.+arl boy+u incubator can be dangerously cooled even when the air temperature in the incubatnyqbl y+. rcaou ;j+3+or is warm. Explain.

Why is the liner of a thermos bottle syowxsyo1m- app 60) fze0) je8ilvered (Fig. 14–15), and why does it have a vacu eoxw8s1zy6yj eo)a)fp-00pmum between its two walls?

Imagine you have a wall that is very well insulated — 3np oa if xdw ;,o2(pm261q-jog5wpmv it has a very high thermal resix3pid1n;p j gq2o fw-pw,maoo2v5( m6 stance, $R_1$ 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) vengy6y)r3-,s k gk 8ewkvtilation 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)gsry g k3k 8)6evkyw,- Heavy curtains reduce which of these heat losses? Explain in detail.

A piece of wood lying in the Sun absorbs more heat s,rm)l 6qvcq. cq p6v4than a piece of shiny metal. Yet the wood feels less hot than the metal when you pi4s 66lccp)qrqvvq., m ck it up. Explain.

The Earth cools off at night much).uiuyblb kb:w, qf19 more quickly when the weather is clear than when cloud: 9b1 .y kubli),quwbfy. Why?

An “emergency blanket” is a thin shiny (metal coated) plastic foil. Explain hlw5e9y-x nb0a7i 0wziow it can help to keep an immobile per7ia5zbyn9x 0- wiwel0son warm.

Explain why cities sh: 8+4uivy 3ffw zvix37q i5xdh;fy(kituated by the ocean tend to have less extreme temperatures than inland cities at th4yi hfiv xy:;w h(z583di7f +qvxk3ufe same latitude.

  How much heat (in joules) is required to raise the temperature of0dl i1602 mu wph8cbfj 30.0 kg of water fu6f 0mpihdj810bl c2wrom 15 $^{\circ} C$ to 95 $^{\circ} C$ ?    $ \times10^{7 }\,J$

  To what temperature will 7700 J of heat raise 3.0 kg of water that is initially ovu:i o gb(:m9;rpq5t at 10o o5g(vu9rbti:q; :pm.0 $^{\circ} C$ ?    $^{\circ} C$

  An average active person consumes about 2500 Caj5tby)4l 0cw u) nzb)nl 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 in the British system of uni0 ,yxah h6k19 wqkjhc4ts. One Btu is defined as the heat ne4q 6xh cj1w0,kh y9khaeded to raise 1 lb of water by 1 F $^{\circ} $ . Show that
1Btu = 0.252kcal=1055J

  A water heater can generathj3; e7*g ezipe $32,000\,kJ/h$ 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 wiljz/7+ p-ukazciu ))ir(mxb mp, 41o kkl take to heat a cup of soup (assume this is 2um/17 ,-p))k(rico+zkibpjmka uxz 450 mL of water) from 20$^{\circ} C$ to 60$^{\circ} C$ .    min

  How many kilocalories are generated when the bn68+-c qa3)dapqpcxsm4 4tzl rakes are used to bring a 1200-kg car to rest from a speed of lq)qam4dc+6scp3 nxp-4t8za $95\,km/h$ ?    kcal

  An automobile cooling system holds 16 L of water. How much heat does it abs/mc0+zmceoqcq4e 5 n ,orb if its temperature e ecc n50/+cqm, oq4zmrises from 20$^{\circ}C $ to 90$^{\circ} C$?    $ \times10^{ 6}\,J$

  What is the specific heat of a metal su.)6 p16aemgdhoqlc f; bstance if 135 kJ of heat is needed to raise 5.)a dmfo 61hpq .ge6c;l1 kg of the metal from 18.0$^{\circ}C $ to 31.5$^{\circ} C$ ?    $J/kg\cdot\,C^{\circ} $

  Samples of copper, alumix*mt/6x e+jxx num, and water experience the same temperature rise when they aemtx/xj+xx *6 bsorb the same 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 thermomey mf(dvx0 *aeh3 /xtr(.b e9xuter 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 equilibrium temperature when a 245-g,b5oumkq::2 mzguqs 7 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 d/wk3rtaxhbz .z) /+z(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 e h6o5hk7(5k*e ws thd:ds 3uxis 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 brl4v d2k*kj 5coil 0.75 L of water initiall4rv*5 ckd2jk 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 of candy from twmbdbynm5 g-efu/2+8he following measurements. A 15-g sample omb ef-wdgmn / +5y2u8bf 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 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 iron at.xma5k), gns(z iax), mx76yd +mbn xn 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 asfq52;re*xmnqckl (r* o/ a k- 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 objecz,orqbb;1.0 )-2 it se,nl (fpmydusd t is defined as the amount of heat needed to raise itrq,dtbb -zssl(yendp0u 1; ).2,fm ois temperature by 1 $C^{\circ} $ . Thus, to raise the temperature by $\Delta\,T$ requires heat Q given by
$Q\,=\,C\,\Delta T$
(a) Write the heat capacity C in terms of the specific heat, c, of the material.
(b) What is the heat capacity of 1.0 kg of water?    $ \times10^{3 }\,J/C^{\circ}$
(c) Of 25 kg of water?   $ \times10^{ 5}\,J/C^{\circ}$

  How much heat is needed to melt 16.50 kg of silver that is i ul7 stepo6s2-nitially at 20$^{\circ} C$?    $ \times10^{6 }\,J$

  A 0.095-kg aluminium sphere is dropped from the roof of a :t .x.d x) qk2xlcie.g45-m-high building. If 65% of the thermal energy prod tixq de:.x c2xk.)lg.uced when it hits the ground is absorbed by the sphere, what is its temperature increase?    $C^{\circ}$

  During exercise, a phgoym*2n:x r) erson may give off 180 kcal of heat in 30 min by evaporation of water from tm2oghyx r: )*nhe skin. How much water 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 it)5h oz)vqv7cz( (imats melting point is dropped into an insulated container of liquid nitrogen. How much nitrogen evaporates if it is at its boiling point of 77 K and has a latent heat of vaporization(amzhqvo ) 5)c zti7v( 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 th,s( 0wo;7ak cei)vfhce 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 at 18p031vkd9u lkl:nax/i $^{\circ} C$. 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 spaniu a/5nx k3;bj of four hours. Making the approximation that all of the cyclist’sxai;35 nku b/j 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 o4z, yf6m60si *xp buu100$^{\circ} C$ 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 merc9sv.m 7hesh q9ury 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 at (jzeur -6-bk8kmi3 f e 6mzw e,j1dw,7i3kfao $250\,m/s$ 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-skaterf4wko rz /y8p/ moving 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 th ae6sjck0l- (iat was stopped in a doorframe apparently melted completely on impact. Assumin(sl6cij0 ae- kg 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 is kept at 46f, r ywo .ty3,r0:ccbl0$^{\circ} C$ , 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 42upfgp 1pgm2 Example 14–10, assuming that there are strong m2f4p upg12pg gusty winds and the external temperature is -5$^{\circ} C$   $ \times10^{4 }$ W

  (a) How much power is radiated by a tungsten sphere (emissivitya.5 bh+c0t gvf $e\,=\,0.35$) 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 by conductio 9:v1 nvz ca.s2vwlh(en from the blood capillaries beneath th wsa1zec hv(lv92vn .:e 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. Beg f.trk rz,:fe1t b2b0cause of a number of 1 g0tft.ez,f:b 12r bkr00-W lightbulbs in one room, the air is at 30$^{\circ} C$, while in the other room it is at 10$^{\circ}C $. How many of the 100-W bulbs are needed to maintain the temperature difference across the wall?    bulbs

  How long does it take the Sun to melt dw6*v9qprl: oz. gxa xzp t(.(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 sam bgm1em9zh v-lh87il 9e length and cross-sectional area are attached end to end (Fig87gz-1 mvh9hlebli m9. 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 w8vib:z ssq 5 ,kqn*+cwhich the whole Earth receives enerqz:8*ciw+ v ,k sbsn5qgy 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 generatesva4av1( v5omu 95 W of heat, which is dissipated through a glass bulb that havou51 4mvv (aas 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 maig2agz k ;q:* pl0dspn6oz4d2jnly from a 4.0-in. layer of brick and an R-19 layer of insulation,l gzs2 6qdo:2n0;da *j4kppgz as shown in Fig. 14–19. What is the total rate of heat loss through such a wall, if its total area is $240ft^2$ and the temperature difference across it is 12 $F^{\circ} $?    Btu/h

A double-glazed window has two panes of glass separ,x ndjur)df )*onup91 ated by an air space, Fig. 14–20. (a) Show thaj*1 9nfp,r)ox)nu u ddt the rate of heat flow through such a window by conduction is given by
$\frac{Q}{t}$ = $\frac{A(T_2-T_1)}{l_2/k_1+l_2/k_2+l_3/k_3}$,
where $k_1$,$k_2$ and $k_3$ are the thermal conductivities for glass, air, and glass, respectively. (b) Generalize this expression for any number of materials placed next to one another.

  Approximately how long s 1cwt*bak l-t*hould 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 aew j 05.t n 8ydt.yjd*g)*hvrwt 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 2)w8ea u;dsoauq c5w539h nrjenergy is contained in the world’s oceans, estimate thece2r; 3qwn9hdowa5)u 8ua sj5 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 estimate.)    $ \times10^{ 15}\,J$

  A 15-g lead bullet is tested by firing it into a fixed bn( jga+n)qi- slock of wood with a mass of 1.05 kg. The block and imbedded bullet together absorb all the heat generated. After thermal equilibrium aj snni)(+g-q 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, assuming it to be a x. 5ru3p*ee*j tvd(;fcl9lql:4d zjl perfect emitter jzll.ult*(4qpe5v9djfr3 c *; :de lx 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 may gen1zzvl 4ky ;+wwerate $200kcal/h$ 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 boulde p; 1yr d9 nwoq;d1twex:/gze+r rolls 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 the heat g+ e;t pow9;d1gxdqw1ezn/y :renerated remains in the rock.    $C^{\circ} $

  A 2.3-kg lead ball is dropped into a 2.5-L inrved*dsky,f ,l xo8- 7sulated pail of water initially at 28l ,o,sk * r7x-dvyfed0.0$^{\circ} C$. 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 jac v-7peu,,fyat*e6e u8 w,jlnxket 3.5 cm thick with total surface areap,,u6 uv8nw-etxjey, l fa* e7 $1.2\,m^2$ 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 avef j*e1z*b 0gxbrage metabolism 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 ciq7 x8a9 bqcv0 90rchoonducted from the interior of the body to thexh80qicbvc9 qo9 a 7r0 surface. 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-insulated walls 17.5 cm thick (assume cog(ks mzf6p11b c5:yqanductivity of air) and area 5p1bsqgacyf1 m(6kz :$410\,m^2$ 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 a5en owz k-m0kl,jue (3t $220\,m/s$ 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 parjzxxwg/ xe uq+) 94w2rt (a) in Problem 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 temperature of e w9/+jwxg2zx xu)4rq35$^{\circ} C$.    g/h

  An iron meteorite melts when it enters the Earth’s atmosphere. If itsfe+u uygtoi*a ;jgq/r023c(.yuhj:u initial temperature wae0/ y h:3tu r;cqa.ug fgyj* j2ui+(uos -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 within the Earoal7t8lfm9g/ k*f3 9k /w rapex/wg4vth’s crust increases about 1.0 C$^{\circ} $ for each 30 m of depth. The thermal conductivity of the crust is $0.80\,W/C^{\circ} \cdot\,m$
(a) Determine the heat transferred from the interior to the surface for the entire Earth in 1 day.    $ \times10^{18 }\,J$
(b) Compare this heat to the amount of energy incident on the Earth in 1 day due to radiation from the Sun.$Q_{Sun}$ =    $ \times10^{4 }\,Q_{interior}$

  In a typical game of squash (Fjbr/4/htl40 ap -xglj1 n1f xbig. 14–22), two people hit a soft rubber ball at a wall until they are about to drop due to dehydrat0fbrlj lj1h aptbxg4 4nx// 1-ion and exhaustion. Assume that 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 equal masses .s4q- hrjmpeksp nwc56l0) p 9of ice at 0$^{\circ} C$ and steam at 100$^{\circ}C $ are mixed together?

  In a cold environment, a person can lose heat by conduct7pgrp*h f b* ch6m/-- h(ufxir rf7/tdion and radiation at a rate of about 200 W. Estimate how long it would take for the body temperature to-b/x6*(tphc /7p-duhrf fr rfmh*gi 7 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 dishwashib-:dj9 fys7v ang, there is “no hot water” left in the 50-gal (185-v bdfsj:a7 y-9L) water heater. 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 surfdci9/x:) n6d g0h mjtiace of a 60-W lightbulb is 65$^{\circ} C$ when the room temperature is 18$^{\circ} $C. Estimate the temperature of a 150-W lightbulb with a glass bulb the same size. Consider only radiation, and assume that 90% of the energy is emitted as heat.    $^{\circ} C$