What happens to the work done when a jar of orange juice is vigorously shaken?ke1d*x x-2 dzp

When a hot object warms a cooler o.y4r3emepe n: bject, does temperature flow between them? Are the temperature changer :pee.n4m3y es of the two objects equal?

(a) If two objects of dif0l, *g)rirlaq g*v/ut ferent temperatures 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 heat to flow evgv*g ) rar qluitl*/0,en if the internal energies of the two objects are the same? Explain.

In warm regions where tropical plants grow but9 c-ctdz507x8u*re rrie w -jj the temperature may drop below freezing a few8-t9dc j-wri 7je u0 err5z*xc times in the winter, the destruction of sensitive plants due to freezing can be reduced by watering them in the evening. Explain.

The specific heat of ucz4n -yc8s s+ ,8m9ug ey3lzlwater is quite large. Explain why this fact makes water particularly good for heating systems (thatl,88gsy4zcu 9u-c+n e3slzy m is, hot-water radiators).

Why does water in a metal canteen stay cooler if the cloth jacket surroundingwu;jqe x00 z+v the canteen is kept moue0 z+xj;0wvqist?

Explain why burns caused by steam on the skin are oft)oizuaha 54iyk 544aoen more severe than burns caused 5i4 aa4u zh5k4ayoo) iby water at 100 $^{\circ} C$ .

Explain why water cools (its temperature drops) when(v0hv szaa0/dfku7wy k(:m: f it evaporates, using the concepts of latent heat and internal energyma0:h(f wyadkk vuvz:7fs/0( .

Will potatoes cook faster if the water is boiling fmp;o3 ib z, mh/piy42g69ir ihaster?

Does an ordinary electric fan cool the air? Why or why not? If not, why use iwgjg aze)9)a,kls1re9u s2 dt(p9d(jt?

Very high in the Earth’s atmosphere, the temperatureoia 4 y(ijpkiv s7mj3-()c yk) can be 700 $^{\circ} C$ . Yet an animal there would freeze to death rather than roast. Explain.

Explorers on failed Arctic expeditions have survived by covering themselves wit( vqn6njv (b-qh snow. Why would tqn-qb6v ((j nvhey do that?

Why is wet sand at the beac2/ci;hbv j)a ah cooler to walk on than dry sand?

If you hear that an object has “high 07+gpwaklqz *3ma2 ab heat content,” does that mean that its temperature is high? Explain. w7pb0aqag 3* z2almk+

When hot-air furnaces a0s)ebp;ui g rh*a26ivre used to heat a house, why is it important that there be a vent for air to return to the furnace? What happens if this vent is r0*2ieauv ; i)h g6pbsblocked by a bookcase?

Ceiling fans are sometimes reversible, so that they drive th.x 84sk r ujxosd7*ib/e air down in one season and pull it up in another season. Which way should you set the fan for summer? For winte.7jxs /u8xdbori*k4s r?

Down sleeping bags and park m3dawyll0x9 5as are often specified as so many inches or centimeters of loft, the actual thickness ofy ma9dx35wll 0 the garment when it is fluffed up. Explain.

Microprocessor chips have a “heat sink” glued on top tw ,bkufiv87vc-p p)i5 hat looks like a series of fins. Why is i-b7i)5uvc pwv8ipf ,k t shaped like that?

Sea breezes are often encountered on sunny days at t(vjr6znc si0znxe5m:2cz;w s9i8;n whe shore of a large body of water. Explain in light of the fact that the teiwsw zxrs8; ;c e5zz0n9nn i:2j (cvm6mperature of the land rises more rapidly than that of the nearby water.

The floor of a house on a foundation under which the air can3vxfj d+pt8+fh0df( k flow is often cooler than a floor that rests directly on the ground (such as a concrete slab foundation). x(8vfp0 fdf+jhdk+t3 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 in7u.0q:thxzf 8zbu 1e f the feufzh8x07b 1 u:qz.t shade.

A premature baby in an incubator can be dangerously cooled even whawpa d (e,rq 5h3-je/4a)vore en the air temperature in the incubator is warm.e q5e/ jaor3,e)varad (w4-hp Explain.

Why is the liner of a thermos jjyg2w0 ko-um fgxva3g4,,l)bottle silvered (Fig. 14–15), and why does it have a vacuum between ix g,j-0g avl3 f) yojku4,m2wgts two walls?

Imagine you have a wall that is very well insulated — it has a vg 386p, os+ywaz0kbe iery high thermal resistance a k,8gbys63w+ize po0, $R_1$ 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 tqw egd1mx/.y1 *y4vevhe following processes: (1) ventilation around edges; (2) through the frame, particularly if it is metal; (3) through the glass panes; and (4) radiation. (a) For txv 1my/* y.w e1e4qdgvhe 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 lyinn)gl s 3o 9j2abf.wj)zg in the Sun absorbs more heat than a piece of shiny metal. Yet the wood feels less hot than the metal when you pick it up. Eszajl3)92 ) bn owgj.fxplain.

The Earth cools off at night much more qum0: m8auz1xw.0w ha yfzdkx. .ickly when the weather is clear than when cloudy8d m wzm xzu0wy a:1..ak0.hxf. Why?

An “emergency blanket” is a thin shyhwa*kb)ey4 u3. (ndlad 3xp-iny (metal coated) plastic foil. Explain how it can help to keep an immobi3d(y*k.u3 wxa-b h 4npda)elyle person warm.

Explain why cities situated by the ocean tend to have less exti:xx;xd;v)nw2ojw1mkw i - 0creme temperatures than inland cities at 20o:kw nx;w1wmicx;j)xd - iv the same latitude.

  How much heat (in jo (+x5r64wnqck sgpo *fules) is required to raise the temperature of 30.0 kg of water (rqwxnf65+ cpkg4*os from 15 $^{\circ} C$ to 95 $^{\circ} C$ ?    $ \times10^{7 }\,J$

  To what temperature will 7700 J of heat raise 3.0 kg of watelh 7u/q g76xeyxk(xb/r that is initially at 10l/7u(x hx67 qgk/xybe .0 $^{\circ} C$ ?    $^{\circ} C$

  An average active person consumes abq;v.nvjys 6k mj. qje( 5-mm7wout 2500 Cal a day.
(a) What is this in joules?   $ \times10^{7 }\,J$
(b) What is this in kilowatt-hours?    kWh
(c) Your power company charges about a dime per kilowatt-hour. How much would your energy cost per day if you bought it from the power company? Could you feed yourself on this much money per day?    dollars per day

A British thermal unit (Btu) is a unit of heat vdms ajp:; jcyz*4/w) in the British system of units. One Btu is defined as the heat neede;/mcp)vsj4yj : a zdw*d to raise 1 lb of water by 1 F $^{\circ} $ . Show that
1Btu = 0.252kcal=1055J

  A water heater can gc9 (vsf6(hp q1 mxt/xkenerate $32,000\,kJ/h$ 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 will p j1+z:srmxlr3o hye9 w0ux92 take to heat a cup of soup (assume this is 250 mes p12 9mrz3hwl09: yrxxjou+ L of water) from 20$^{\circ} C$ to 60$^{\circ} C$ .    min

  How many kilocalories are generated when the brakes ar( )uv:x.fe; jbv8 lsfl0n7ewne used to bring a 1200-kg car to rest frsnefujbvx. ;(8l v0:nlw7 ef)om a speed of $95\,km/h$ ?    kcal

  An automobile cooling system holds 1r*ds- t50q.a5vp vprn6 L of water. How much heat does it absorb if its temperature rises frv5np0rrs -q atvp.5*dom 20$^{\circ}C $ to 90$^{\circ} C$?    $ \times10^{ 6}\,J$

  What is the specific heat of a mrcp1oyy 70n ; ue 1ge4as6;troetal substance if 135 kJ of heat is needed to raise 5.1 kg of the metar1pe ;o rnu04eo ygy;1tca76s l from 18.0$^{\circ}C $ to 31.5$^{\circ} C$ ?    $J/kg\cdot\,C^{\circ} $

  Samples of copper, aluminum, and wateul(x bu(,bq c2dz5xkz:rnk*md *:y 6gr experience the same temperature rise when they absorb the same amount of heat. What is the ratio of their masskluybu(* :zqrd*cxm2:ng ( dxb5 z6,kes? [Hint: See Table 14–1.]$m_{Cu}$ : $m_{Al}$ : $m_{H_2O}$ =    :    :   

  A 35-g glass thermometer reads t qta h4+wnu8d6a/jg;c hgz9521.6$^{\circ} C$ 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 at 2u534c 9)sutvcs kihfm7l* x0o 85$^{\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 q7;,l6 nk c2d1p k*fnt:graoq= $0.4\,kg$) 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 is heateuss+5w2 +vbu sd 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 0.75 L of water 5)a p4l y:murf;b td +l/f6zo+ u0ucstinitially fu:+b + m6cp4zslradu0ttu /yo l)f 5;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 the fo vu o7bht71z+reh3oy1llowing measurements. 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 0y b371h1uo hvr+ozet7 .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 afv8 :j-r uei2ot 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 ham a5xw9ish 8ikmd;og6z jb+8 j/mer 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 e iktl-o7sv8tl4 5 zl1r 1xf.mheat needed to raise its temperature tf -.ekli5 8x7t1lms1r 4vozl 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 16.5yd:i(vmx9 wm myr -9u30 kg of silver that is initially at 20$^{\circ} C$?    $ \times10^{6 }\,J$

  A 0.095-kg aluminium sl6ia: ddj5)nq phere is dropped from the roof of a 45-m-high building. If 65% of the thermal energy produced when it hits the ground is absorbed by :na)jid56dq lthe sphere, what is its temperature increase?    $C^{\circ}$

  During exercise, a person may give off 180 kcal of heat4(ax:kemqke:ggou 7 8 in 30 min by evaporation of water from the skin. How mx4 :eokq7g umka: (g8euch 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 dro+h spm q(5i+4cpmr,3futpl( g3zzb z,pped into an insulated container of liquid nitrogen. How much nitrogen evaporates if it is at its boiling point of 77 K anz ,blp 3 3zgpqus(mzpfm(,+hi+ rt5c4d 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 tak1x74l 8jk5hw lnmo t, bycpy45en 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?    $ \times10^{-3 }$ kg

  An iron boiler of mass 230 kg contains 830 kttsjl.wd:xr:(4n c5 pg of water 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 L4qq e;;kv -vlk8ia gw0 of water over the span 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 consumed does go tow g8v;4-qkkvl 0ai;eq heat, so our approximation is not far off.)    kcal

  What mass of steam at 100lb ; (eu.g1vji$^{\circ} C$ 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 mercumbxue02 u d,,b 7jw4tary 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 travelilz o1eq,8s*z hvo,k h mr)a3)uu5, fgdng 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 xvk -2x:*ygpt)rg y4vmoving 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 forensi* i5ws1 97wjbqu7o uqauj, zd)c investigator notes that the 8.2-g lead bullet that was stopped in a doorframe apparently melted completely on impact. Assuming the bullet was fired at room temperature (w*u5aj7qdq7 1s,bzouiwj9) u20$^{\circ} C$ ), what does the investigator calculate as the minimum muzzle velocity of the gun?    m/s

  One end of a 33-cm-long aluminum rod wittmx o/7;g-jt9:xizs t0m6t* m i ibg6bh 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 14–10, assuming t 6o 8/yivp.wqahat there are strong6ap y8qiv.ow/ gusty winds and the external temperature is -5$^{\circ} C$   $ \times10^{4 }$ W

  (a) How much power is radiated by a tungsten sphere (emissivityh7hxu od jk(y6 3rg-i7 $e\,=\,0.35$) 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. Supq objr(nz4xtw7va +,7pose 200 W of heat flows by conduction from the blood capillaxnzrq7 w4bt7(ov , +jaries 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 per side, share a 12-cm-thick brick wall. Because t+ v(w;6yp;rgm(m krzu) k3rs of a number of 100-W lightbulbs in one room, the air iskp+y3v)t (rg k w(rsr6;;umm z 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 Sbct 0/jdt:vh 6un to 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 lengtb snlg 4nlg855h and cross-sectional area are attached end to end (Fig. 14–18). The copper end is placedlbn4n5glg 8 s5 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 constanv: x hizx)s8y-.e:wz ot, estimate the rate at which the whole Earth receives enerxyhw .:-z)vxs z 8o:eigy from the Sun.    $ \times10^{17 }$W
(b) Assume the Earth radiates an equal amount back into space (that is, the Earth is in equilibrium). Then, assuming the Earth is a perfect emitter ($e\,=\,1.0$) estimate its average surface temperature.    $^{\circ} C$

  A 100-W lightbulb generates 95 W of hea.jj 6)5desm aat, which is dissipated through a glass bulb that has a radius of 3.0 cm and ij.a )m6jaed s5s 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 mainlzqs2) x/5qh ps.qu )4g nec8tly from a 4.0-in. layer of brick and an R-19 layer of insulation, as shown in Fig. 14–19. What is the total rate of heat loss through such a w4xpg/2sz)e qns8c5l. qth)u qall, if its total area is $240ft^2$ and the temperature difference across it is 12 $F^{\circ} $?    Btu/h

A double-glazed window ha2/; tte/sqh lus two panes of glass separated by an air space, Fig. 14–20. (a) Show that the rate of heat flow through such /qe;/2 tthusl 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 )ib2wbv89k:bzv*dte lk 84 tuit 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 kgl(ozvz1 ok(x0(5e c h: ldbzh. 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 $30\,MJ/kg$ 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 energyw-r4 66 wtvniy is contained in the world’s oceans, estimate the hew -6wt46ynvirat 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 fixz;ll5eg;go zk,; alqk- u .l)oed block of wood with a mass of 1.05 kg. The block and imbedded bullet together absorb all the heat generated. After thermal equilibrium has been reached, qlu; a-elk k .,lo)lg;zg;zo5the 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 6+aajxb-vz6+ ;wj qfa it to be a perfect emittw b6xfaq-zjaj;++v6a er 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 pezvf+zjsqch2re/5vl,3it / 9m /fptn :rson 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 boulwd zhn9yz2v90h,2foep. )rt dder rolls off the top of a cliff and falls a vertical height of 140 m before striking the ground. Estimate the temperature rise 02dr, v9)zfh td.h29wpz yoen of the rock if 50% of the heat generated remains in the rock.    $C^{\circ} $

  A 2.3-kg lead ball is droppedv;+rtt4ejoci lmmd.e .t4e,w 9f;et* into a 2.5-L insulated pail of water initially at 2 ;.e9 eme4*vw,. +j;t omrftttecldi 40.0$^{\circ} C$. If the final temperature of the water–lead combination is 28.0$^{\circ} C$, what was the initial temperature of the lead ball?    $^{\circ}C $

  A mountain climber wears a goose down jacket 3.5 cm thick with total surface arehv 08, mlr l uvr0+o0r)l/p:koasn3fz m8)ah rl pv 00fo zv,rln/s+oklur0:3a $1.2\,m^2$ The temperature at the surface of the clothing is -20$^{\circ}C $ and at the skin is 34$^{\circ} C$. Determine the rate of heat flow by conduction through the jacket
(a) assuming it is dry and the thermal conductivity k is that of down,    W
(b) assuming the jacket is wet, so k is that of water and the jacket has matted to 0.50 cm thickness.    W

  A marathon runner has an average metabolism rate of mx);ffd26n2iuhw yy, 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 fraqhn;d 3 hgch 2;,0gd rfp m7r*2*nxfmom the interior of the body to the surface. Assume that the thickness of t, hc0hqd;*rafmh mp*ngd3n2gf7xr 2 ;issue 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 conductivity of4p *rfx9vts 75zmtw y2 air) and area 4v7y9 2sxtwz*mp5r tf$410\,m^2$ 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 am95ez wk2( pqh 3iyd7dts 1-ydt $220\,m/s$ 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 inmo m;mr n+ncz;n-(hs*sy0+wk to account radiation from the leaf to calculate how much water must be transpired (evaporated) by the leaf per hour to maintain nn0( sn +rmkz;+*cwmm;-yhos a temperature of 35$^{\circ} C$.    g/h

  An iron meteorite melts when it enters the Earth’s atmosphere. If its initia:z t* g bfc bsds0fz.81l 2kihb4wu5p;l tezc. :2bwdz0i*ks s4b fh81tgpu5fb l;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 the Earth’s crust increases abouzteyn3 -4 cdk6*w8v/*rs, yaiu.yv ett 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 squ jp.4/u2hp x noelwgamw4,c);ash (Fig. 14–22), two people hit a soft rubber ball at a wall until they are about to dwxempuoc.2gan/ j), hw4 p;l4 rop due to dehydration 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 equacud gkv,,) 7pml masses of ice at 0$^{\circ} C$ and steam at 100$^{\circ}C $ are mixed together?

  In a cold environment, a person cmbpx;5 wji -zy l*,7vj*3rlzd an lose heat by conduction and radiation at a ratl- p7ijz drjzl3x ywbvm *;5*,e of about 200 W. Estimate 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,2kjzr p*qhwv ,e2h-.t there is “no hot water” left in the 50-gal (185-L) water heater. This suggests that the tank 2q2wzhpjr*e -. ,khvthas 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 ligzg19j./( j4htrs( e4oxslm iuhtbulb 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.    $^{\circ} C$