What happens to the work done when a jar of orange juice is vigorously shajk4z ldso ej- re349;zken?

When a hot object warms a cooler object, does temperatur*hmmu*3uy t5 ; /kqkci,+pzrde flow between them? Are the temperat 5/p*uz r ckq3;*kmhyu,+imdture changes of the two objects equal?

(a) If two objects of di te)6k5dmumk;gt1*rw t 2ml2rfferent temperatures are placed in contact, will heat naturally flow f mttmgk*m5) l16; rewd 2ukr2trom the object with higher internal energy to the object with lower internal energy? (b) Is it possible for heat to flow even if the internal energies of the two objects are the same? Explain.

In warm regions where tropical plants grow but the tevt )sz )h21h8e:ewfcemperature may drop below freezing a few times in the winter, the destruction of sens)v:esee 1c h)thwz28fitive plants due to freezing can be reduced by watering them in the evening. Explain.

The specific heat of w23mnek4f2i+tm ard:c ater is quite large. Explain why this fact makes water particularly t earfimm+cd:kn2342 good for heating systems (that is, hot-water radiators).

Why does water in a metal cak5gj o;8rwfjc tb7 (*vnteen stay cooler if the cloth jacket surrounding the (ov t g 5rjk;c7j*w8fbcanteen is kept moist?

Explain why burns caused by steam oxasfvj*.h5ow l2+v 0j n the skin are often more severe than burns caused 0w a5.xlj2f ov+*hs vjby water at 100 $^{\circ} C$ .

Explain why water cools (it7k dvxqheu ;81+ tdze-h/dh;i s temperature drops) when it evaporates, using the concepts of latent heat and internal enerh;zv ite; qdkd+uhx- /d8h e71gy.

Will potatoes cook fastezzo.m3bxn. (e r if the water is boiling faster?

Does an ordinary electric fan cool the air? Why or why not? If not, ei teo5889ci iwhy use it?

Very high in the Earth’s atmosphere, the temperature1gk ,pzi5i dpsdr :da1hj1:m : can be 700 $^{\circ} C$ . Yet an animal there would freeze to death rather than roast. Explain.

Explorers on failed Arctic expeditions ha *r+0sxf)wwtwx8 u .avve survived by covering themselves with snow. ta+s * x)u0v8rw wwfx.Why would they do that?

Why is wet sand at the beach cooler to wal ;u:w: d;1gkby+miwrly62y j hk on than dry sand?

If you hear that an object has “high heat content,” does that meanf tf3,.fl,pmm that its temperature is high? Ex.3m,p mfflft,plain.

When hot-air furnaceq 1w.x d,a3fk1kfnu vb jb8e/ocz+) c8s are used to heat a house, why is it important that there be a vent for air to return to the furnace? What hao3+xj 8c,kqf/au k)dw8ezc 1 n 1f.bvbppens if this vent is blocked by a bookcase?

Ceiling fans are sometibpjil t p)9p: b/ai ilv0fd )8ukp/79ames reversible, so that they drive the air down in one season and pull it up in another season. Which/kpa8aipb)v l )j0:/p d9fbti 9lup7i way should you set the fan for summer? For winter?

Down sleeping bags and parkas are often specifu7 qp)e- c3ttzied as so many inches or centimeters o ue cz)37ttq-pf loft, the actual thickness of the garment when it is fluffed up. Explain.

Microprocessor chips have a “heat sink” glued on top that looks lik./pxq9zg2wdg e a series of fins. Why i2z/q d .wxp9ggs it shaped like that?

Sea breezes are often encountered on sunny days at the shok-pp m80f79bvjq 4q eare of a large body of water. Explain in light of the fact that the temperature of the land rises more rapidly than that of the nearby wm8v4qpbfj 97qk0-a p eater.

The floor of a house on a foundation under which the air can f dz *(b:hf/gialow is often cooler than a floor that rests directly on the ground (such as a concrete sab/zfi gh*d:( lab foundation). Explain.

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

Explain why air temp0a96s xpyer33 rb7d p:vvu:uk erature readings are always taken with the thermometer in the shx6::pur3y bv e 7ua90dpsr3 kvade.

A premature baby in an incubator can be dangerously cooled even + m2 r6wyjbxl.when the air temperature in the x+w2b. lr6ymjincubator is warm. Explain.

Why is the liner of a thermon y b3-vp3t981dmngul(fccf7;. q z /ai q.xdos bottle silvered (Fig. 14–15), and why does it have a vacuum between its two walls?qcvtdgp7 c(ua-y.d/.n3x i 1lf 8 nzmb 9qf3o;

Imagine you have a wall that is very well insulated —m1 l /8cjma7ks it has a very high thermal rsm7c /mjlk8a1esistance, $R_1$ 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 fo hq7u: nx pkb-xl8.e)/zfv2 bullowing processes: (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) Heavy curtp7ul b:xevb.kzhf8x)n 2 u- /qains reduce which of these heat losses? Explain in detail.

A piece of wood lying in the Sun absorbs mo7 )5p:zx4huiov6u f xfre heat than a piece of shiny metal. Yet the wood feels less )p56x47iuvh x:fz o fuhot than the metal when you pick it up. Explain.

The Earth cools off at night much more quickly when the weather iskvq1d z 3coi/: clear than when cloudy. Whyvc:i zoq /3k1d?

An “emergency blanket” is a thin shiny (metal u8pg,x8 eb3uts;kl1r coated) plastic foil. Explain how it can help to keep an immobb;38tul 8guk ep x,r1sile person warm.

Explain why cities situated by the ocean tend to have less extre -+/2z;pisu/ tphk ickme temperatures than iis/p;-u/tpk c+kh z2inland cities at the same latitude.

  How much heat (in joules) is required to rai.fq;wv 5yoaana -o7syky :w .9se the temperature of 30.0 kg of water from 1yakq an;-5yo oyvf s7:w.w.a95 $^{\circ} C$ to 95 $^{\circ} C$ ?    $ \times10^{7 }\,J$

  To what temperature will 7700 J of heat raise 3.0 kg t g:wtw skdw59 r+/t(dof water that is initially at 10.s5dk9dt/ tw:+tgwwr( 0 $^{\circ} C$ ?    $^{\circ} C$

  An average active person consumes about 2500q(**ljdtab 3j 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 in the British systvxi,sn+ck6snj . /jqvie82 9 cem of units. One Btu is defined as the he eqijcck 26 x/n+v,9in8vs js.at needed to raise 1 lb of water by 1 F $^{\circ} $ . Show that
1Btu = 0.252kcal=1055J

  A water heater can generate ./c az d;n hnuuykwb s+4ut((.$32,000\,kJ/h$ 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.e 0yjf3hwxw7. Estimate how long it will take to heat a cup of soup (assume this is 250 mL of xw0j7 we3yfh. water) from 20$^{\circ} C$ to 60$^{\circ} C$ .    min

  How many kilocalories are generated when the brakes are used to bj/ kg82xs ct9sring a 1200-kg car to rest from a spests 28/xkg jc9ed of $95\,km/h$ ?    kcal

  An automobile cooling system holds 16 L of 8lzij cbn l j- .0a6woo)mqiwa0* zd38water. How much heat does it absorb if its tea)l8 o3*j0 0-icb 8nizamwqzw. dl jo6mperature rises from 20$^{\circ}C $ to 90$^{\circ} C$?    $ \times10^{ 6}\,J$

  What is the specific heat of a metal substance isj,wol .pw7s.f 135 kJ of heat is needed to raise 5.1 kg of thewjwo sp,s 7l.. metal from 18.0$^{\circ}C $ to 31.5$^{\circ} C$ ?    $J/kg\cdot\,C^{\circ} $

  Samples of copper, aluminum, and water ex6bqn- x q7qj *z *jeh/kbb4u2ma0,dhjperience the same temperature rise when theye0qnjq4k2zm6 bubb-xqjd* j*a ,h/7 h absorb 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 thermometer reads 2xd- nzp(6d .bt1w 1wwml1qw 4m1.6$^{\circ} C$ 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 whe2 1-i rdq65pndzxxqm/n 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 (maseq +rt0 10ghuky ra0:jvb1d,us = $0.4\,kg$) 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 wa4:,qti.,rr2uh m: iljgn w(substance 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 coffeepot to bring to a boil 09ijmvb z)88b0qtr )l i.75 L of water initial9jzi)mbbqt08r 8vi)l 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 6zq*qm8.puiwcfgo . pl)6g0.*bk al eof candy from the following measurements. A 15-g sample of t*lg k o.f)q *66p.iucbwgzp 0lqa8em.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 iron apg3tgti4n2c 4l f*;n m 8nf7vjt 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 spi-n7g(ayzy5r ,;xnu deed 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 amoun qb 3o7.p-cbqat of heat needed to raise its temperaturcb 3qp.a7qbo -e 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 inid4tj8cx.z ;s vtially at 20$^{\circ} C$?    $ \times10^{6 }\,J$

  A 0.095-kg aluminium sphere is dropped from the)boi0d++s+)ywsi wkm roof of a 45-m-high building. If 65% of the thermal energy produced when it hits the ground is absorbed by+sb mw) dk0iwi ys)+o+ the sphere, what is its temperature increase?    $C^{\circ}$

  During exercise, a person may give off 180 kcalqb*vb/9zo2e;vf sk e) /z 6unb of heat in 30 min by evaporation of wabbbn 9v/s*)/6k;vz o qz efue2ter from the 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 its melting point is dropped into an insulated container o1ds7vfbrqo**v d 0 uss9b7q*v z l4vz*f liquid nitrogen. How much nitrogen evaporates if it is at its boiling poi7*914vo0d f dbsl*vv*qqzu7 vbz*ssrnt 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 fr zau iuks8nxhs9c*s1 th,+:0h eezer 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 18p01dv6a2v9cq4bo rbz$^{\circ} C$. 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 consurlby+zzd* ,9 nd9l sb/mes 8.0 L of water over the span of four hours. Making the approximation that all of the cyclist’s energy goes into evaporating rb ds,*l/ldn+9z bzy9 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 100w3aneu5 a 8k(g$^{\circ} C$ 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 mercury 4*ylm uy (2nrbu4x6 dlis $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 y( agm-8xl/.vo z2hub $250\,m/s$ 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-skatert nyet9/67kcl 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 leadjci4u ll bns90fbx6j 1.b7 pd3 bullet that was stopped in a doorframe apparently melted completely on impact. Assuminlsbln b416dxif0 p u7b9j3cj.g 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 alpx64id xlk0x1b kp .0;q;zwowuminum 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 conduction in Example 14–1 ,s3t7p cgixg0g3pfl-esv5)k0, assuming that there are strong gusty winds and the external temperature is -5 v5sfe3)c7xk3,p 0gt -isgpl g$^{\circ} C$   $ \times10^{4 }$ W

  (a) How much power is radiated by a tungs g*w8ohv iw gcwwqqg,i11d66*ten 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 skn5 dw8jyqy i8,c(t0wdin. Suppose 200 W of heat flows by conduction from the blood yc(50nj8,qditd yw8 w capillaries beneath 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 pe00;+ hpee mhtor side, share a 12-cm-thick brick wall. Because of a number 0 othpe+e 0hm;of 100-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 cr+kp;*bztbgkf94e/ z j(m8 h melt a block of ice at 0$^{\circ} C$ with a flat horizontal area $1.0\,m^2$ and thickness 1.0 cm? Assume that the Sun’s rays make an angle of 30$^{\circ} $ with the vertical and that the emissivity of ice is 0.050.    h

  A copper rod and an aluminum rod of the same length and cross-se dtwvcjx*; 9k4ctional area are attached end to end (t94kcwj dx;v*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 a0 mfpqhsd 8l,5n ;-sm tlg1j1st which the whole Earth receives energy from the Sun. p1,0n l;q jlmts8hg5sd 1-fms   $ \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 gener fhbp(pir/f**ates 95 W of heat, which is dissipated through a glass bulb that has a radius oi(rph bp**ff /f 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 wqf.n8 *(ivbkuall of a house come mainly from a 4.0-in. layer of brick and an R-k 8nvi*u fb(q.19 layer of insulation, 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 )sn+22q nczbxc0 - dgqseparated by an air space, Fig. 14–20. (0ns n x)qcdq cz2gb-+2a) Show that 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 lonf0b xbc1w- b8eimvly-2 (o p ty ew*3,08mjougg should 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 liqu)ly 1tqebhz a1s+ 3y;hid 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 contained in the world’ss ba 36jxl2fd4 oceans, estimate the heat liberated when a cube of ocean water, 1 km on each side, is cooledxsb dl f6ja234 by 1 K. (Approximate the ocean water as pure water for this estimate.)    $ \times10^{ 15}\,J$

  A 15-g lead bullet is tested by firing it into a fixed block of wood with a masswk,b ffcsq)ao/;.z8zbd w:xizgd/ / 2 of 1.05 kg. The block and imbedded bullet together ab:zic xfz;gdwk s)of/dq8b / /b w,2az.sorb all the heat generated. After thermal equilibrium has been reached, the system has a temperature rise measured as 0.020 $C^{\circ} $. Estimate the entering speed of the bullet.    m/s

  (a) Find the total power radiated into spacyy n/ p 4al:47/ru)srx2cxxl de by the Sun, assuming it to be a perfect emitterlr7n p4 ylrxu2xsxy)4:d/ a/c 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 activityc w2 3 6wkci*gb:fjvq4jo(m x,, 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 oc(xto5 lje73 off the top of a cliff and falls a vertical height otox(3e j57lo cf 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 insu s-)qr2+aag kzlated pail of water initially at 2aqg) s+zr-a2k0.0$^{\circ} C$. 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 wc1ga/mv)a1j f:vg *wsith total surface area j:wg* gfav1 c/m1av)s$1.2\,m^2$ 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 averageg, dd+)ujyryb8 e;jy* 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 conducted from tc l 8cjxataf 1+m:2:2ws-rwmj he interior of the body to the surface. Assume that the thickness of tissue is 4.0 cm, that the skinajrcfm 1m8j2sxcw:w2 l- a+:t 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 b( whs1t18us3,n vde) .uuejkcm thick (assume conductivity of air) and area ede us.1v)ukb ut1 nws 8,(3hj$410\,m^2$ 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 traz z,.ybk63xcwveling 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)sx y9ma2lmi: 58, take into account radiation from the leaf to calculate how much water must be transpired (evaporated) by the leaf per hour to maintaini) x:alm 9sy2m a temperature of 35$^{\circ} C$.    g/h

  An iron meteorite melts when it enters tc2 7kzmz)u 2f mu+m-dehe Earth’s atmosphere. If its initial tee7um-+ uzm2 cfz dk2m)mperature 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 within ts-6 k0.vik1i* z)acsqo f7 c ar*9relqhe Earth’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 (Fig. 1p 0mk:qqbthy +jf 0c8q mq+,s*4–22), 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 th+y+0 q8f:bqsh, m*jtq0m p kcqe 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 o8s( x;8 i(:lp5kvrikkaud1a/ovds i1f ice at 0$^{\circ} C$ and steam at 100$^{\circ}C $ are mixed together?

  In a cold environment, a person can lose heat by conduction and radwfn55c hic2u u e2o)a0s -x-o9w .bu0p *qiijjiation at a rate of about 200 W. Estimate how long it would take for the body i 0acj2e5- w po5q-cx 9u*bh)0wfsji.2uiuno 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 i4o uqy08 nbkto nq58s1s “no hot water” left in the 50-gal (185-L) water heater. This suggesb8n48k1 n0q 5qo otuysts 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 60-W lightbvfp nci:e) 6c)g*o2y eulb 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.    $^{\circ} C$