What happens to the wo-n4zf+. oqrxf rk done when a jar of orange juice is vigorously shaken?

When a hot object warms a cooler object, does temperature flow between them? Are3 bitc++r4a8sc q,hk3 hcs hk1 the temperature changes of thethhsikc a8c1r3,s 4q+ bk ch3+ two objects equal?

(a) If two objects of different temperatures are placed in con0/gm nu-j 9.wzgkxn)ftact, will heat naturally flow from the object with higher internal energy to the object with lower internal energy? (b) Is it possible for-w/m fgn)kzxn.9gj 0u 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 temperature mayoe)4.: ofsmr(ujg . vw drop below freezing a few times in the winter, the destrucojvr. (g e.f4s omuw):tion of sensitive plants due to freezing can be reduced by watering them in the evening. Explain.

The specific heat of water is quite large. Explv)s- o b o70,n.e:jxfprhhly/ain why this fact makes water particor hvfo,/hx.0)bsl:j ep7n-yularly good for heating systems (that is, hot-water radiators).

Why does water in a metal canteen 3vg8xe,r yi6qdi-)t1ggwf .i ( *t bwastay cooler if the cloth jacket surrounding the canteen ix3 wq(w*1 iafgge dyb)ig irt-8 v.,t6s kept moist?

Explain why burns caused by steam ond ,cd.pg9thv xy 8c26r the skin are often more severe than burns caused ,ct.6hxcyrvp 2g d89dby water at 100 $^{\circ} C$ .

Explain why water cools (its temperature drops) when it evaporates, using the *1g),fzyt0lhi.,l fuo gc7g econcepts of ,lgc.e) ilfuz1 o,gt7g0f h y*latent heat and internal energy.

Will potatoes cook fu eey*7 1lnrqw , j.n1*msz)rsaster if the water is boiling faster?

Does an ordinary electric fan coo n/6b6g:ialzq).t.tz pdlb 1 vl the air? Why or why not? If not, why use it?

Very high in the Earth’s atmosphere, the temperqd2p-3zbj*y y ature can be 700 $^{\circ} C$ . Yet an animal there would freeze to death rather than roast. Explain.

Explorers on failed Arctic expeditions have survive:1om+;i *ob(h nktv aid by covering themselves with snon1;i+v oakoh:b*it (m w. Why would they do that?

Why is wet sand at the beach cooojmg:1d y9lj o9 tg:,wler to walk on than dry sand?

If you hear that an object has “high heat content,” doeb *x+og:th +1ad9blnes that mean that its temperature is high? Explaitdxle 9h1bo+ :gn +b*an.

When hot-air furnacesy1zz7s4n xr l0 are used to heat a house, why is it important that there be a vent for air to return to the furnace? What happens ir7 n x0zzl4s1yf this vent is blocked by a bookcase?

Ceiling fans are sometimes reversible, so that they drive the air dow .ho lb(fr)p-vn in one season and pull it up in another season. Which - .bvlfo()p hrway should you set the fan for summer? For winter?

Down sleeping bags and parkas are often specid/ 1k/t mhu.dhfied as so many inches or centimeters of loft, the actual thickness of the garment when it is fluffed up. Exm1hkhdt.u/ d/ plain.

Microprocessor chips have a “hea+m5 iap3;vp oct sink” glued on top that looks like a series of fins. Why is it shaped like that?pm +i5c3aop;v

Sea breezes are often encountered on sunny days at the shore ohlt2yo: -h5vt-m on+jf a large body of water. Explain in light of thel2onh+t -ty5m jh-o: v fact that the temperature of the land rises more rapidly than that of the nearby water.

The floor of a house on a foundation under which the3p4wkbhx10h nqf4z:(1xyum a air can flow is often cooler than a floor that rests directly on the ground (such as a concrete slab fofyz0 hn3ax(q4bp 1u4h m:x1kwundation). Explain.

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

Explain why air temperature readinghdb2gvsvo/ (z) v.yn7 s are always taken with the thermometer in thevdvyzb v/(.sogn h)7 2 shade.

A premature baby in an incubator can be da 8 f)aiun9fprk ujkckvtb23+i,u 22*fngerously cooled even when the air temperature in the incubr 83 iu kk9u,k2pffnufc)j*itva2+2bator is warm. Explain.

Why is the liner of a thermos bottle silve3b,).yaby2xhi,6segm ) vere ,a i 9oured (Fig. 14–15), and why does it have a vacu bb m,viehgo) xye ,i.2a3eur9,) sy6aum between its two walls?

Imagine you have a wall that is very well insulated q yrqux) 69j2/owon k+— it has a very high thermal resistauqyowxr2+ 69k)nj oq /nce, $R_1$ 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 i8g1k fnvj v08the 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 the first three, what is (are) the mechanism(s): conduction, convection, or radiation? (b) Heavy curtains reduce which of these heat losses? Explain in detaig0jknvv f i881l.

A piece of wood lying in the Sun absorbs more heat than a piece of shiny metam2nw(1ow52 ,u2r4z;r tsmilcw,x qem4t + qpel. Yet the wood fee42qmti14 rw(me sncq t+ow, 2 5r2epu l;m,xwzls less hot than the metal when you pick it up. Explain.

The Earth cools off at night much more quickly,vsk e ko5;n1rgxs0xszbhr9b+ f f- 37 when the weather is clear than when cloudy. Wh9zgnb0bksrx+3s1fr,7ks o;fve 5h - xy?

An “emergency blanket” is a thin shiny (metal coated) plasticceumup 2*k6 *uu3h-xxq-(cbb foil. Explain how it can heceh**c b--kbuu xx2pm(u6u 3qlp to keep an immobile person warm.

Explain why cities situated by the ocean tn .ckr(8h *rvan j(vc9end to have less extreme temperatures thanc(r9r vv8nk nhcaj.(* inland cities at the same latitude.

  How much heat (in joules) is required to raise the tyx6yj-p ku70i7trl e3emperature of 30.0 kg of water36ulk70 p7yrx tj-ie y from 15 $^{\circ} C$ to 95 $^{\circ} C$ ?    $ \times10^{7 }\,J$

  To what temperature will 7700 J of heat raise 3.0 kg oxaxd66b2 t xos o*2,bdn/2yebf water that is initially at 10.0nod exb6b22 o s ty,xb/a6*xd2 $^{\circ} C$ ?    $^{\circ} C$

  An average active person consumes about 2500 Cal a dalx- ..svm s 2 cy0du06fsj/gfdy.
(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 ux.i hv)gmr(7sp 9if- ghb5c:d nits. One Btu is defined as the heat needed to raise 1 lbs7- b(rhidcmx 5g9h)pvg :. fi of water by 1 F $^{\circ} $ . Show that
1Btu = 0.252kcal=1055J

  A water heater can gewo d/s22 odm6tnerate $32,000\,kJ/h$ 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 lon)wyb v eco5rawt-:z 62g it will take to heat a cup of soup (assume this is 250 mL oy-w2w)tz6e:orb a5v cf water) from 20$^{\circ} C$ to 60$^{\circ} C$ .    min

  How many kilocalories are generated bzl9n aj0qvv 1gs. *f7when the brakes are used to bring a 1200-kg car to rest from a9 b 1vfq zgnsa7j0vl*. speed of $95\,km/h$ ?    kcal

  An automobile cooling system holds 16o: ba0xg6g)ve6 rp, aw L of water. How much heat does it absorb if its te)ax age vw:, o0g66bprmperature rises from 20$^{\circ}C $ to 90$^{\circ} C$?    $ \times10^{ 6}\,J$

  What is the specific heat of a metal substance if 135 kJ of heat hz8s12ghv xv 5p:9 dx +*n)mfczk.nh zis needed to raise 5.1 kg of th v9zdn+ g hhvx2x5*.p8mh skcz1:fn)ze metal from 18.0$^{\circ}C $ to 31.5$^{\circ} C$ ?    $J/kg\cdot\,C^{\circ} $

  Samples of copper, aluminum, and water ey4p8 2yb2 mkztxperience the same temperature rise when they absorb the same amyzykbp 4m 22t8ount 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 re7jy6t ;vmui jcxg i.c;3-7gf cads 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 a1,q2)v. hh 0htkllgsyt 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 (masb zr1wy + ,e3)n.u(roni.spsks = $0.4\,kg$) 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 heated to 3tcba.3iwb,sng ;gxnmp :3 k+ ;30$^{\circ} C$ 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 bri-ilw -dartl6 ,xf0t 8cng to a boil 0.75 L of water initially at 8.0,0lx -t c8-wlrtfai6d$^{\circ}C$? Assume that the part of the pot which is heated with the water is made of 360 g of aluminum, and that no water boils away. $\approx$    min (Round to the nearest integer)

  Estimate the Calorie content of 75 g of candy from the following measurhtllr:/ z:0d1x+3 tgllzu rj- ements. A 15-g sample of the candy is allowed to dry before putting it in a bomb calorimeter. The aluminum bomb has a mass of 0.725 kg and is placed in 2.00 kg of water contained in an aluminum calorimetez +lt:llxldrh:grju-3z1t 0/r 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 a)e :ak3qqb(ajmus+ nue13;l ywj6 h1180$^{\circ} C$ 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 hammeqesb.b6 9 2p7psi b/enr 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 heat needed todt +qvlt 2(61 td5besj raise itsqd ts( vt+te b61j2d5l 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 thw. tt*kr )lp )+tksfe(at is initially at 20$^{\circ} C$?    $ \times10^{6 }\,J$

  A 0.095-kg aluminium sphere is dropped from the roof of a 45-xik:+s 4,/k(ogupq(c ucx r(sm-high building. If 65% of the the: uou,/ c pxcgskr (ik+qs(x(4rmal energy produced when it hits the ground is absorbed by the sphere, what is its temperature increase?    $C^{\circ}$

  During exercise, a person may give off 180 kcal of heat in 30 min b:6 sjx ,bvh ;gbk-h4c,oojyr+y evaporation of water fjcog sbb h+ko6h y,:v-;rx,j4rom 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 containerzo8o/0y qjcx1+mgq2 v of liquid nitrogen. How much nitrogen evaporates if it is at its boiling poiqo1mxc2 j+zyqvo0 /8gnt 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 frew iep re + xrp34blgiztg80g794tt1,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 oi gb3l jf5aw mbg1bg32p70.j contains 830 kg 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 L of water over n6y8sfmr vh 44the 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 6f4r4v yhnms8 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 ak g1-xeqj :ec*i6t/ny6 xzyv9pqa7 8 et 100$^{\circ} C$ 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 oxoz //6v;)y.z.f7o zame9 k 1tcururis $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 travelidmp:2fpz) g :fng 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 moviyzijb px4+ yk+fj(dqqm wxb/3f:.)r)ng 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 8.216z;dzd guj9 l-g lead bullet that was stopped in a doorframe apparently melted completely on impac;lu96g1zd jd zt. 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 ajz-oks ; v/te uopt222bjae7; 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 flo tfx 5n:kt1 rykxx;xk.w94+rkw by conduction in Example 14–10, assuming that there are strong gusty winds and t k5rt:1xkkx+y9k;trx nx4.fwhe external temperature is -5$^{\circ} C$   $ \times10^{4 }$ W

  (a) How much power is radiated by(3 g0f jqkas i7t z27oxh-7anx 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 conduction fcghjg5imn n- ( -6kk2erom the blood capillarie5 nk(eg-2-gcn himk j6s 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 garus.qzl3o;7*sv6 /,i c gmg a 12-cm-thick brick wall. Because of a number of 100-W lightg uar73sv ,gzio s;q*g. lc6/mbulbs in one room, the air is at 30$^{\circ} C$, while in the other room it is at 10$^{\circ}C $. How many of the 100-W bulbs are needed to maintain the temperature difference across the wall?    bulbs

  How long does it take the Sun to melt a bp9s 2c9y beu0nlock 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-mbk3- xi/ glr2sectional area are attached end to end (Fig. 14–18). The copper end is placg-m32x kli/bred in a furnace maintained at a constant temperature of 250$^{\circ} C$. The aluminum end is placed in an ice bath held at constant temperature of 0.0$^{\circ} C$ . Calculate the temperature at the point where the two rods are joined.    $^{\circ} C$

  (a) Using the solar constant, estimate the rate at which the m bp)+;rw q4u:idz.qkwhole Earth receives energy from thep.q d; rqbm wzu+ki):4 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 genx9hu* r c:t6y /(euzsfa/ysc 1/wubsb3sq4l +erates 95 W of heat, which is dissipated through a glass bulb that has a radius of 3.0 cm and is 1.0 mm thick. What is the differencebsc6e1w/uufs(u/ q:r+ / 94ssylxay*bth3 zc in temperature between the inner and outer surfaces of the glass?   $^{\circ}C $

  Suppose the insulating qualities of the wall of a house come mainly from a 4.0- dse/gzd6 r baz7g 57m;z-u1hdin. 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 wall, if its todsrze 7du 1g/bz-zma756dh ;gtal 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 separated by an air spa zh rf(1cy+.ksce, Fig. 14–20. (a) Show that the rate of heat flow through such a window bsf. hry1( zc+ky 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 take 1ih- ocv +ey5x(xtad,)1.0 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 0.20cop-w98q1+ hc:jo ypqyef39 p kg of liquid at 5$^{\circ}C $. Drinking this liquid can actually consume some of the fat in the body, since energy is needed to warm the water to body temperature (37$^{\circ} C$). How many food Calories should the drink have so that it is in perfect balance with the heat needed to warm the liquid?    C

  If coal gives off $30\,MJ/kg$ 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 w/ 5io-d(;b45 ipta s-etshuh is contained in the world’s oceans, estimate the heat liberated when a cube of ocean water, 1 to-d-5s/ pawtu hbh;s ei54i( 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 block of woyftqvs8 i7r ps8r rt-))o0bz 4od with a mass of 1.05 kg. ryrvt)i)0s r4 zt-b78 pf os8qThe block and imbedded bullet together absorb all the heat generated. After thermal equilibrium has been reached, the system has a temperature rise measured as 0.020 $C^{\circ} $. Estimate the entering speed of the bullet.    m/s

  (a) Find the total power radiajm,(tmcn 5m6 ited into space by the Sun, assuming it to be a per6mj ,tmnc5(imfect emitter 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, dprv3j 8tu y(cx;c-kkz1 s; a*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 off the toc3uvj8g8 z6z9 /2dre num hzf2p of a cliff and falls a vertical heightzc3uz z6f2/vd hj enmg828 u9r of 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 insulated pail of water initially7gmd srnb;1vi . (6+si(chvio at 20.0 r6(ig7.cmv( shbns1id; iov+$^{\circ} C$. 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 tot)wfn iat:c1 0fke62 btal surface areai)fb2 fa0e6cttn k1:w $1.2\,m^2$ 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 18jh;fe6z l- hxd9 b k+zzzaj5juh1 ;yrate 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 ckjpqw6r+1b /n onducted from the interior of the body to the surface. Assume that the thiw+61bkjpqn /r ckness 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 tf83o bwee e,-chick (assume conductivity of air) and area f,w 3e8beeo c-$410\,m^2$ 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 travhpclbi, v1i2qb8m 6 ,beling 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 Problm hpa8:qvlu-s/s*e :c em 58, take into account radiation from the leaf to cc:*:vlaqshmse/pu 8 -alculate 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 it enters the Earth’s atmosphere. If its initia6zmyn qlcz6y,-n 3ca6 l tempe-ml6cn ,zcyn36a6yz qrature 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 cru)o esexfk 9y6a*s5 m;tst 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), two peoplhm7csf/6f vc88lmjd61yjq4 le hit a soft rubber ball at a wall until they are about to drop due to dehydrati8 f8ycms/d1ml6cq64v hfljj 7on 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 resunwf azog+y/ a3lnjh7sndyhi q .;/7:8lt when equal masses 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 conduction and radiation at e s3deb0bn0h9a rated 09b3ebse hn0 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, there is “no hot water” left izijug-rpue3qpi: /t /q 84v/jn the 50-gal (185-L) water heater.vtpz/u/ 34gp8qjqji / ru:ie- 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 surface of a 60-W lirg 3ym .(4uj(wz .u3edyyory9 ghtbulb 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.    $^{\circ} C$