What happens to the work done when a jar of orange juice is vigo*rld/aem xoa z 5v6d9:rously shaken?

When a hot object warms a cooler object, does tempera13sm) vzka t9jr0ul 4mture flow between them? Are the temperature changv0u k)a4jl sr93ztmm1es of the two objects equal?

(a) If two objects of different temperatures are placed in contact, will heatgqu*-4 ;) 6nvyvb5 inswubel( naturally flow from the object with higher internal energy to the object with lower interna-g6 )in;q ewul(*5vuvy4nb s bl 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 plantb4b4)i bm-dtfi a* o(cs grow but the temperature may drop below freezing a few times in the winter, the destruction of sensitive plants due 4)dbctib4 fb*oi am(- to freezing can be reduced by watering them in the evening. Explain.

The specific heat of water is quite large. Explain why this fa :(p hk3 bdfucz:o(e;gct makes water particularly good for heating systems (that is, hedu :;3chpfoz( k:g b(ot-water radiators).

Why does water in a metal canteen stay cooler if 6 )*;i f pe/ohpt/+lm a5xvbyxthe cloth jacket surrounding the canteen is i/aey6m5) /x;o l* vh tb+pfpxkept moist?

Explain why burns caused by steam on the srfqd+ kq ) *zv6gpr,;cx-g7c, szvt +xkin are often more severe than burns caused by water a fx,z;, c +dzkqs)-6c t7rv*qvxpg+ grt 100 $^{\circ} C$ .

Explain why water cools (its temperature drops) when it evaporater 6 rjyj/yd0/ qwq7dd)s, using the concepts of latent dq j/r/ r6)d0yw7dj qyheat and internal energy.

Will potatoes cook faster if the water i fv11mx,wrdpge2;nq8 s boiling faster?

Does an ordinary electric fan cool the air?yn5( 8kurgps; Why or why not? If not, why use it?

Very high in the Earth’s atmosphere, the temperature wc jkl0ds 2 u,zvtf446r(x5 pecan be 700 $^{\circ} C$ . Yet an animal there would freeze to death rather than roast. Explain.

Explorers on failed Arctic expeditions have survived by co01rr v0d; yzxovering themselves with snow. W1vy r0r0od z;xhy would they do that?

Why is wet sand at the beach cooler to walk ono . dq9trjj+a7 than dry sand?

If you hear that an object has “high heat content,” does that mnyvfy3c5;5n 5u b+lro ean that its temperature is high? Ex3 fuyr;c555bnylvo +n plain.

When hot-air furnaces are used to heat a house, why is it important tha qit os:) egpqt-m,6* u-vegh1t there be a vent for air to1m-g ut)h 6q*-s og t:peve,qi return to the furnace? What happens if this vent is blocked by a bookcase?

Ceiling fans are sometimes reversible, so that they drive the air down y;72 :uh8 kpdth(xsxlin one season and pull it up in another season. Which way should you set the fan for summer? Fo( kud2thy7l xspx;h: 8r winter?

Down sleeping bags and parkas are often specified as so many inches oz,gq7q5 yt /+rtxi/w nupyo:)r centimeters of loft, the actual thickness of the garmentu+oyi x:qz) /twg5rpnyq /, 7t when it is fluffed up. Explain.

Microprocessor chips have 3ad 9 kf2ccqnej v77r:a “heat sink” glued on top that looks like a series of fins. Why is it shaped7 7v jec:29dncf ka3qr like that?

Sea breezes are often encountered on sunny days ak 2 3d3g.qxgez k5* rn nla2uto7h5w:pt the shore of a large body of water. Explain in light of the fact thap5 53ah.n2 7wkdxet3:ggrkq*2u znolt 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 fl 0iclmy-di0k8*v xt.t ow is often cooler than a floor that rests directly on the gmtk l.c8xi0*id-0v ytround (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 readi o (yztmr)ofh:mr)(mkmc +w., ngs are always taken with the thermometer in the s rcyommfm tr)+:.kzhwm (,()o hade.

A premature baby in an incu5 a x8uqe w2ucrd6)ggxt:i4xtyx:f38bator can be dangerously cooled even when the air temperature in the incubator isd 2)xi w6 x:t 8ugyefr xgatx:c43u58q warm. Explain.

Why is the liner of a thermos bottle si cj+ dt1ry7h,ulvered (Fig. 14–15), and why does it have a vacuum between its two 1dy,cj+ u7rthwalls?

Imagine you have a wall that is very well imkqv1*h1m:o:6 o fz oynsulated — it has a very high thermal resisvf1:mq:6 1 omo ohyzk*tance, $R_1$ 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:0unz4uetp .g windows by the following processes: (1) ventilation around edges; (2) through the frame, particularly if .4n:u0zegutp 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 the Sun 7ocp qk ;ho 6nbc-48udg3yud-absorbs more heat than a piece of shiny metal. Yet bg ; 7udhu onqpc4yc3d86o k--the wood feels less hot than the metal when you pick it up. Explain.

The Earth cools off at night much more quickly when theubgf.x *ck1kmv/ a8kv 1ina5( weather is clear than when cloudy81* k5fkamiv1 kba(gx / nc.vu. Why?

An “emergency blanket” is a thin shiny (metal coated) plastic foil. ss7kvwy - mc+r+;j7qb Explain how it can help to keep an immobile person waw 7 7q+sbmky+sc;r-jvrm.

Explain why cities situated by the ocean tend to have l8b vbrg hb1v84cox :.ness extreme temperatures than inland cities at the sag14rcb:h8nv bv 8xob.me latitude.

  How much heat (in joules) is required to raise the temperatur;frah poyfaiq4s46ta*e42kb(+gzc ,e of 30.0 kg of waterp+y 4zi;fg,thqc*6a( aaskf 2r 4o4eb from 15 $^{\circ} C$ to 95 $^{\circ} C$ ?    $ \times10^{7 }\,J$

  To what temperature will 7ymu; (h96yg4tdfk3wbm0w 63 5mrgp it700 J of heat raise 3.0 kg of water that is initially g m33yukh4i(y w5mf9;trgtmd p0 6wb6at 10.0 $^{\circ} C$ ?    $^{\circ} C$

  An average active perso v.4dadec dr6(qz+a )2c*af sd8 b:gzvn consumes about 2500 Cal a day.
(a) What is this in joules?   $ \times10^{7 }\,J$
(b) What is this in kilowatt-hours?    kWh
(c) Your power company charges about a dime per kilowatt-hour. How much would your energy cost per day if you bought it from the power company? Could you feed yourself on this much money per day?    dollars per day

A British thermal unit (Btuwb8p w nz-1c3b) is a unit of heat in the British system of units. One Btu is defined as the hebwc-n3zb1 8w pat needed to raise 1 lb of water by 1 F $^{\circ} $ . Show that
1Btu = 0.252kcal=1055J

  A water heater can g5o rck 1mtie-(enerate $32,000\,kJ/h$ 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 8+fss9icic/ p bcx9ive4d., s350 W. Estimate how long it will take to heat ass4.d9,bc 8xfce+ icpv9/isi cup of soup (assume this is 250 mL of water) from 20$^{\circ} C$ to 60$^{\circ} C$ .    min

  How many kilocalories areggm1 ;i c-5iom generated when the brakes are used to bring a 1200-kg car to rest from a speed of1m-iom gicg5; $95\,km/h$ ?    kcal

  An automobile cooling system c0+h.1 /+gjew( zg25-s ,hlft nivq ou/tqsmq holds 16 L of water. How much heat does it absorb if its temperatuv+hw+f.tg0 /5qgcq/iot el q s,(2umh-sn 1zjre rises from 20$^{\circ}C $ to 90$^{\circ} C$?    $ \times10^{ 6}\,J$

  What is the specific heat of a metalsol13.i /rdc71l; qlojshgz m9 yop75 substance if 135 kJ of heat is needed to raise 5.1 kg of the metal from 18l;3gdmq57z/.sypcoro s 9 o17 il 1jlh.0$^{\circ}C $ to 31.5$^{\circ} C$ ?    $J/kg\cdot\,C^{\circ} $

  Samples of copper, aluminum, and water experience the same tempe lh 40u8b3per6l;di ograture rise when they absorb the same amount of heat. W48dpe l;obh l igu306rhat is the ratio of their masses? [Hint: See Table 14–1.]$m_{Cu}$ : $m_{Al}$ : $m_{H_2O}$ =    :    :   

  A 35-g glass thermometer ret3cafge4j:(w vy7 sq-ads 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 block of copper at63 cqcxz:0 iqzgng4j 4ya,q/u 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 (mt:;8.yvlmtze4 h e2fnass = $0.4\,kg$) 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 mw+ pzt(/yn f 27q9vfasubstance 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;+pa zr*uy-y rgu o,y:w+t3c(b 0 lt2 ehs8smf to bring to a boil 0.75 L of water initially at hsu(fgt -uyp28s r+z3 c*yt:oy 0 w;lar+m,eb8.0$^{\circ}C$? 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 fyij abs28 q5n8rom the following measurements. A bnsqa 8 258yij15-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 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(m *+fe/1 zk1y yugrua 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 ha6jhn dz, t+(esl0)ni 5hp4wj4ugk+ xlmmer has a 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 object is defined as the amount of h9kc /y ob4x9lweat needed to raise iwc xl99ky4ob /ts 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 f ioa+ an), c0upntb5- ; eiieq(mq/r)of silver that is initially at 20$^{\circ} C$?    $ \times10^{6 }\,J$

  A 0.095-kg aluminium sphere is dropped o d-/y1 wx lf d/1mkl8ulo4zsfa)3fc 5from the roof of a 45-m-high building. If 65% of the thermal energy produced when it hits the ground is absorbed by the sphere, what is its tempdw81y 4xu)/ scfkolz 1 dlml3 f5of-/aerature increase?    $C^{\circ}$

  During exercise, a person may give off 180 kcal of heat inlv(8qk 8s*d qc 30 min by evaporation of waterdlq(v8*c qs8k 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 p(9fi* oj::v.e9cayjwo( e vm container of liquid nitrogen. How much nitrogen evaporates if it is at its boiling point of 77 K and has a latent heat of vaporizc 9 we(j.9*pvv ::jm(yaeifo oation 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 freezer a jia2ac1ov42dt -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 waterlsixpa s8 )o.( at 18$^{\circ} C$. A heater supplies energy at the rate of $52,000\,kJ/h$ How long does it take for the water
(a) to reach the boiling point,$\approx$    h (Round to one decimal place)
(b) to all have changed to steam?$\approx$    h (Round to the nearest integer)

  In a hot day’s race, a bicyclist consumes 8.0 L of water over the syg +-rk (qjv)d/i;) w cbuf0adpan of four hours. Making the approximation that all of the cyclist’s energy goes into evaporating this water as sweat, how much energy in kcal did the rider use during the ride? (Since the efficiency of the rider is only about 20%, most of the energy + dd (/;wukaivcr)) gfb -q0jyconsumed does go to heat, so our approximation is not far off.)    kcal

  What mass of steam at 1o -zh:o;p7c q6 y cb/ip.niq9v00$^{\circ} C$ 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 mc6, 53q pr(,m:vnp t wepc:lqmercury 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.q +picziief; hq92ga vt)r5. at $250\,m/s$ penetrates a block of ice at 0$^{\circ} C$ and comes to rest within the ice. Assuming that the temperature of the bullet doesn’t change appreciably, how much ice is melted as a result of the collision?   g

  A 54.0-kg ice-skater movingx1 /9yidchon je()b.r 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 int. + 1jaltw5ahvestigator notes that the 8.2-g lead bullet that was stopped in a doorframe apparently melted completely on impatat .1 +aj5lhwct. Assuming the bullet was fired at room temperature (20$^{\circ} C$ ), what does the investigator calculate as the minimum muzzle velocity of the gun?    m/s

  One end of a 33-cm-long aluminum rod with a diameter of 2.0 cm is ke*3 loqg+ae .nppt 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 14–10, a,cw2 zsog8w3z ssuming that there are strong gusty winds and the external temperature is -5c w8 zg23zsow,$^{\circ} C$   $ \times10^{4 }$ W

  (a) How much power is ;d :a+ofvhi+,6puj 0d,i fsf wradiated 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. Suppose 200 W of heat flows by condu9er z9ztgzw 8*ction from the blood capillaries ben*gze wt8 z99rzeath 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 bricr-n;1 ur6mk brk wall. Because of a number of 100-W lightbulbs in one room, the am6 rk-;r bn1ruir 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 bq;v:ftq(f7 hp oq+/e 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-sec +r1 :egm9tat p3.usiotional area are attached end to end (Fig. 14–18). The copper end is placed in a furnace maintained at a constant tempe o9ts.gu+:i1p t ra3emrature 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 who:-2qp ubo bya.le Earth receives energy pyq-:ao2.ub bfrom 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 throcm9z 7d3x p8i ;iaz2sgugh 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 surfaces of the ggs;ii8 7dzpmz3 2xc 9alass?   $^{\circ}C $

  Suppose the insulating q -v zz/5f), swfmht6.ruzj e7zualities of the wall of a house come mainly from a 4.0-in. layer of brick and f -zr .szzhj6m5 ufw/)t,ze7v an R-19 layer of insulation, as shown in Fig. 14–19. What is the total rate of heat loss through such a wall, if 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 glasa51,p/ wndnnmo4cqg5nf i7 3js separated by an air space, Fig. 14–20. (a) Show that the rate of heat flow thwp5, nd7o in1jfnmq3cn4a/ 5g rough 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 should it takef:xtd :,,knmja13 g3 wr g gw7-ac8nbe 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 liqufx5 gx3rd1ub; m9p*alve g3n.id 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’s o-zbdybgv- 2w75bo (qd-p j: jgceans, estimate the heat liberated when a cube of ocean water, 1 km on each side, is cooled by 1 K. (Appod jyvq2 w-z-gb7p g(bj: b-5droximate 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 woo1*iuz4c ubl *ed with a mass of 1.05 kg. The block and imbedded bullet together absorb all the heat generated. After thermal zucb4*ui *le1equilibrium 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 S *zq74o+io0yhy t2pogun, assuming it to be a perfect emitt7o2ho* o4+q0 tpz ygyier 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 m/ga-xehz;m ,npof +(lbdi s/- ay 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 rollv0jb;f bu3b *os 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 hjv0ob fu*; b3beat generated remains in the rock.    $C^{\circ} $

  A 2.3-kg lead ball is dropped into a 2.5-L insulated pail:qo -2w 8t8j;rkelggbta +ol2 of water initially at 20.0+kg2ae t tb-wjo8o;l rqg82:l$^{\circ} C$. 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 jack b+v-kcl9 t7rfas:k4bet 3.5 cm thick with total surface area 9br vk tfbs4l-:ck7a+$1.2\,m^2$ 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 a di 7,:1mgj .d 5z5aqb6k pvqyu80piujverage 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 the interior of the body t3l ,n0gysga lql7-rf2o the surface. Assume that the thickness of tissr 2sg30qfll7n,yl- ag ue 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 chs*+hi d*t51f tdx:c;dbartc s2;d (oonductivity of air) and areax s5t12* ( odras+ci *f; hdd:h;tcdbt $410\,m^2$ 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 jlf.b jq52 p9iat $220\,m/s$ passes through a thin wall and emerges at a speed of $160\,m/s$ If the bullet absorbs 50% of the heat generated, (a) what will be the temperature rise of the bullet? (b) If the bullet’s initial temperature was 20$^{\circ} C$, will any of the bullet melt, and if so, how much?    $C^{\circ} $

  A leaf of area $40\,cm^2$ and mass $ 4.5\times10^{-4 }\,kg$ directly faces the Sun on a clear day. The leaf has an emissivity of 0.85 and a specific heat of $0.80\,kcal/kg\,\cdot K$.
(a) Estimate the rate of rise of the leaf’s temperature.    $C^{\circ} $
(b) Calculate the temperature the leaf would reach if it lost all its heat by radiation to the surroundings at 20$^{\circ} $C.    $^{\circ}C $
(c) In what other ways can the heat be dissipated by the leaf?

  Using the result of part (a) in Problem 58, take into account radiation from+-qbhy x )hqxq)h0.sw the leaf to calculatxb).s+w hqxyh0 q-) hqe how much water must be transpired (evaporated) by the leaf per hour to maintain a temperature of 35$^{\circ} C$.    g/h

  An iron meteorite melts when gltnczulw :e541 78ptxbk5g6it enters the Earth’s atmosphere. If its initial temperature wapc4z u:6x5 k1g7bw 8eltgl5tn s -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 Earth’s cri +pwhv4,ic (pgn7c4v ust 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. 14–22), tw;sc+ oeh.ipo :j6n6twx3getdxj x.6 (o 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 woxp.j xotsen6i6xhwjc ;3.et (:6 g+d all 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 may /bg7 t-d vexhhi+0)g i*tv6usses of ice at 0$^{\circ} C$ and steam at 100$^{\circ}C $ are mixed together?

  In a cold environment, a person can lose heat by conductilwcxjipx,bz -l/ l7;a6 -vh+yon and radiation at a rate of about 200 W. Estimate how /l,6ybh7v-l;-ix aj xcwzl+p 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, lyo/b9- ( rwemthere is “no hot water” left in the 50-gal (185-L) water heater. This suggests that the tankbrye ol(/ w9-m 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 sujpbxoc3g74 ( arface 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.    $^{\circ} C$