What happens to the work done when a jar of orange juice is vigorous 5vedhsq616drly shaken?

When a hot object warms a cooler object, does temperature flow betweenz7 n ;td1g p;w7,a yz5kvqcb nh7st8(a them? Are the temperature changes of the two objects equal?da ac;b7n1hkq pz5tgyn z( 7;sv7 tw,8

(a) If two objects of diffes1edess 8calfw*ws qm;++*j reo2d 57rent 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 s8w fe+;1qj* dse* mcos+le5dwa s7r2 even if the internal energies of the two objects are the same? Explain.

In warm regions where tropical plants gr7g2wxwja( qv.rde v65ow but the temperature may drop below freezing a few times in the winter, the destruction of sensitive plants due to freezing can be rexvgav( 6qj5w edw.2r7duced by watering them in the evening. Explain.

The specific heat of water is quite large. Explain why this fact m c7a1m bnk +zv6yut 7ezvc74/takes water particularly good for heat 1n/zyku7vazttv mcb7e+ c764ing systems (that is, hot-water radiators).

Why does water in a metaltknwxc9gm:us: *. g(p; om+ yg canteen stay cooler if the cloth jacket surrounding the canteenpc+mu:*g.tn oxmw9yg ( sg;k: is kept moist?

Explain why burns caused by snrm +fc +8m5/knbzse /team on the skin are often more severe than burns caused by waterr8efsn n+z c/b+/mkm 5 at 100 $^{\circ} C$ .

Explain why water cools (its teu.n-k divs*f2*qv db*6 qc1ramperature drops) when it evaporates, using the concepts odvrv1u * .6 s2faidc*qb*k- qnf latent heat and internal energy.

Will potatoes cook faow 2gwp3/he4t ster if the water is boiling faster?

Does an ordinary electric fan cool the air? Why or why 51wltk v;5s.dpgby +fnot? If not, why use it?

Very high in the Earth’s atmosphere, the temp;;rj ww:awl2o erature can be 700 $^{\circ} C$ . Yet an animal there would freeze to death rather than roast. Explain.

Explorers on failed Arctia *85i m6yv9,h cpev(tg8vlhyc expeditions have survived by covering themselves with snow. Why would they do 6h8tih5v amev,y(* 89pgvyl cthat?

Why is wet sand at the beach cooler to walk oq 01p zxfzx4rb z+y);i gf.d4en than dry sand?

If you hear that an object has “high heat content,” does that mean that its3*rzfu l eweq gwz7r thj+ (*2;yp8tv2 temperature is high? Explwywg uzv2eh *3p7f*l82rq+rzt(; tjeain.

When hot-air furnaces are usedw izh/ya;0xtd6 j cs4qe1;*bd p 6 p6lo1rv0er to heat a house, why is it important that there be a vent for air to return to the furnace? What ha*jqbpd6z/ 6y i rdha l14 s0e01x vo;6rctwpe;ppens if this vent is blocked by a bookcase?

Ceiling fans are sometimes reversible, so thauw-( qrzt)a 6jt they drive the air down in one season and pull it up in another season. Which way should you set the fa-jz)6 aqt wu(rn for summer? For winter?

Down sleeping bags and parkas are oftena1a.lgv le p,- specified as so many inches or centimeters of loft, the actual t-1vg a.al, elphickness of the garment when it is fluffed up. Explain.

Microprocessor chips have a “heat 3eqyq4kj 5vp6sink” glued on top that looks like a series of fins. Why is i4yvqjq5p 36 ekt shaped like that?

Sea breezes are often encount 5wph vl-5q r5eqe6j1zh3uxhmh1)aq( ered on sunny days at the shore of a large body of water. Explain in light of the fact that the temperature of twh5l6jz1hxeh 1m53)-a (eqh q5qvpu rhe land rises more rapidly than that of the nearby water.

The floor of a house on a foundation under whi 5f26havgxj1g ch the air can flow is often cooler than a floor that rests directly on the ground (1v5gj2 fhx 6agsuch 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 readings are always py7jah bt*9nje/. z+ rtaken with the thermometer in the sh7*nzbyrj.atj h p/9+eade.

A premature baby in an incubator can be,dcwhc0a pozn; dh* 7) dangerously cooled even when the air temperature in the incubator 0c ad7dc,;o)wphhn * zis warm. Explain.

Why is the liner of a ther(6i eekf1cen- mos bottle silvered (Fig. 14–15), and why does it have a k-1e(ce efin6vacuum between its two walls?

Imagine you have a wall that is vo 7ut gupvk,v9r weow95rww.2i0 v ja6: dc.f3ery well insulated — it has a very high thermal resis w9e r7vvdwf6:vj ,rwcuia5p.o go.2w30t9uktance, $R_1$ Now you place a window in the wall that has a relatively low R-value, $R_2$ What has happened to the overall R-value of the wall plus window, compared to $R_1$ and $R_2$ [Hint: The temperature difference across the wall is still the same everywhere.]

Heat loss occurs through windows by the following processes: (1) ven(;u anq-+0z7-lecwm gbcca )htilation 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+c0z a7 -uhc- qlem cwban)g;( these heat losses? Explain in detail.

A piece of wood lying in the Sun absorbs more heat than a piece of shii0az j fuqj169k1d3 9+1x o*rpieochgv ai3+dny metal. Yet the wood feels less hot than the metal whenkd6 3gj0 z*oiv 1ro aq +ijfxd3p9c1eu9ih+a1 you pick it up. Explain.

The Earth cools off at night much more quickly when ty0e ,)mrfa*4 xuc;ko she weather is clear than when cloudysakex; *) ry cfm4o,0u. Why?

An “emergency blanket” is a thin sa0i( e:*v 9rsiiv m4ucmc 5kh;)(ds cwhiny (metal coated) plastic foil. Explain how it can help to keek c:0;ih vr9(m d*sccw ) 5aseu4iiv(mp an immobile person warm.

Explain why cities situated by the ocean tend to have less extreme tempxd/(+)zgeuxhr qq2s 8eratures than inland cities at the sq h u sdq/rzg)8(e+2xxame latitude.

  How much heat (in jor0ee/ / fkhze.ules) is required to raise the temperature of 30.0 kg of water from 150frek/z/ e. eh $^{\circ} C$ to 95 $^{\circ} C$ ?    $ \times10^{7 }\,J$

  To what temperature will 7700,w26*7wlgogcy nmw efco99 p, J of heat raise 3.0 kg of water that is initially at 10.07 wgog,9wyc eoclm,w2* nf69 p $^{\circ} C$ ?    $^{\circ} C$

  An average active person9uc5x kq w7 7byt7).oyxl 9svx 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 (Btu) is a unit of heat in the British system i1fr rwt/82qb of units. One Btu1it8r2 bq /rfw is defined as the heat needed to raise 1 lb of water by 1 F $^{\circ} $ . Show that
1Btu = 0.252kcal=1055J

  A water heater can gen7 -8f:w,pipnk(x k xoaerate $32,000\,kJ/h$ 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 350gh (2,: qxki-seo; mvy W. Estimate how long it will take to heat a cup of soup (asexi ,sym2o;q(g :h-v ksume this is 250 mL of water) from 20$^{\circ} C$ to 60$^{\circ} C$ .    min

  How many kilocalories are generated when o9 c)9dinb,):aref.j -xmi jv the brakes are used to bring a 1200-kg car to rest fr9j-bifxn,ej) v)9 rc .m:id aoom a speed of $95\,km/h$ ?    kcal

  An automobile cooling system holds 16 L omnq9n 5 b2c px3crscppg* whzrj4*:93f water. How much heat does it absorb if its tehnns3b4* m*c9w5gjcppr2x z:r q9p c3mperature rises from 20$^{\circ}C $ to 90$^{\circ} C$?    $ \times10^{ 6}\,J$

  What is the specific heau)s*8s.qtd n:kw ri3b t of a metal substance if 135 kJ of heat is needed to raise 5.1 kg of the metal fro kr *bn.qsuwd8it :3s)m 18.0$^{\circ}C $ to 31.5$^{\circ} C$ ?    $J/kg\cdot\,C^{\circ} $

  Samples of copper, aluminum, and wates- 2w d/p+ccter experience the same temperature rise when thes w -2/d+cpcety 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 21.dq gm;l3t 9 p5s4d8gcikw z2rp3.f(ma6$^{\circ} C$ 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 equilibriumio(cl g5; :*rsltxhv;utvdm g -ksa6 f7x+p05 temperature when 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 (mapkrp+: w8/zg/ l61.n) l d9ogvp jkkhcss = $0.4\,kg$) 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 330* 4uubm4-ik wh$^{\circ} C$ 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 wyi 8, 0gklpvqf1x,vk-5 ig/ciater initially at 8gcfiv,kgy/ l 8v1pikqx50 , -i.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 following measurements(qzla3 9vo5pv- 4,a ph( g+boqipqy:k. 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 calorimeter cup of mass 0.624 kg. The initial temperature of the mixtur4( 35, paqqv+9i vopzkq g-(ypl b:ahoe is 15.0$^{\circ}C $ , and its temperature after ignition is 53.5$^{\circ} C$ .    Cal

  When a 290-g piece of iron at 186j*- wb zny4vy0$^{\circ} C$ 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 hn8rxl5)ymi0 x.lb . qo3zdq6wammer 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 k rv7jaz ;h qm/t3*go6object is defined as the amount of heat needed to raise its tem37kh/ qjva6to *;grm zperature 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 neededtkvb;s18qr 5. ud+qub to melt 16.50 kg of silver that is initially at 20$^{\circ} C$?    $ \times10^{6 }\,J$

  A 0.095-kg aluminium sphere is dropl3psc xlm*a. /ped from the roof of a 45-m-high building. If 65% of the thermal c sp .*/xmla3lenergy 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 5tn1m oanenzu(u axuj9(+99c30 min by evaporation of water from the skin. How much water has been lo majn9(xzneno(cu51a u9 tu 9+st?    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 3v sacm.u7rt* )em(rk is dropped into an insulated container of liquid nitrogen. How much nitrogen evaporates if it is at its boiling point of(*tr3e mrku7m.)avcs 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 from2s r7y3)b- ivsy- nobo 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 kg of water at 18edq.3 ytak7 h-$^{\circ} C$. 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 bicyk;6m7vxysqqf;.tht lw1xh 6sc12 -h iclist consumes 8.0 L 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 to heat, so oufq6 2- 7l k1xtq1; wivh h.tyh6;csmxsr approximation is not far off.)    kcal

  What mass of steam at) b rujo5/gmn6 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 mercu yjnj 3/w/ylcqz3(1 +i-hcpmnry 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 ild 7ev xxrg)h,o/n1; 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;(7 s vo+o vbmosfk3e2 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-zx .v* oci fkww,8,a+pg lead bullet that was stopped in a doorwi.a,x ,op 8v*z+fw ckframe apparently melted completely on impact. 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 2.00tdy/gnx r/s m4 9(cbc 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 Exag 4 f,rcsr9b:dmple 14–10, assuming that there are strong gusty winds and the external temperature if,r s9g:drb4 cs -5$^{\circ} C$   $ \times10^{4 }$ W

  (a) How much power is radi g4g9qhh4j f7 jfnfxhb,:59bo zzmr77 ated 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 heaj3qc.qflj 6i5 4lqu 3wt flows by conduction from the blood capillaries b j6.5cq w3uqf ilq4j3leneath 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 y,ae 3 foi)xntmo/16l 4.0 m per side, share a 12-cm-thick brick wall. Because of a number of 100-W lightbulbs in one room, thox t i)l/3m1a6y,onef e 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 block of i1zjd 5i 6ogpt.ce 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-clyk yf7, v4ew /pb6y-rgtt((sectional area are attached end to end (Fig. 14–18). The copper end is placed in a furnace maintained av-4,y /kt (rgy l7 (tfwy6pcebt 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 whole Earvkha. fs27pu fmr8 fh2(8sx2zth receives energy from the Sun. 7rhup(ah. 822fv2 zx fs8f smk    $ \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 t q2cn93u e ;o),2zu fk(bwruoohrough a glass bulb that has a radius of 3.0 cm and is 1.0 mm thick. What is wok 32f9 ru);on2e,qouu bc(zthe difference in temperature between the inner and outer surfaces of the glass?   $^{\circ}C $

  Suppose the insulating qualities of the wall of a hous-ttb -,h-/ c m-scpjfme come mainly from a 4.0-in. layer of brick and an R-19 layer of insulati,p t--b-m jc/-cfhms ton, 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 hfx n8qzxm.7+ jas two panes of glass separated by an air space, Fig. 14–20. (a) Show that the rate of heat flow through such a window by conduction +j8 qz7mfxn x.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 11.0 kg of ice at /icn(vhj5j: u+g; (d s vx ztxva5*o7l0$^{\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 abo rdc8z5 7mxgx7km1jg*ut 0.20 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 igsz*w5 4v63dy c wuqc:s contained in the world’s oceans, estimate the heat liberated when a cube of ocean water, 1 km on each s yudv*564wcgs c zw:q3ide, is cooled by 1 K. (Approximate the ocean water as pure water for this estimate.)    $ \times10^{ 15}\,J$

  A 15-g lead bullet i hlm09;y9 .btgl96 fl4f upazis tested by firing it into a fixed block of wood with a mass of 1.05 kg. The block and imbedded bullet together absorb all the heat generated. After t;gplhub llia9 .4f9 t90mfz6y hermal 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 space by the Sdy n cos)k* .g.b9,xjeun, assuming it to be a perfect emo xds*g)b9.y ckn,j e.itter 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 activityl 5bo wy,ukor,2-ro + mw(:rjx, 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 top of a cliff and falls a vertical 6+,se up6m+5w8 g8xq nc hrsteheight of 140 m before striking the ground. E w6n sx86+ut5pe c+qrshg e8,mstimate 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 inr2o2g tco7w t-;ahqk8gx6za(hf:a9m sulated pail of water initially at 29f;o(:2mq2rhgtao- xw7 h8gtz a 6ck a0.0$^{\circ} C$. 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 surfalip8+ 7o jeh7iwq9on+xb+qu*ce area op+9wilonq j 8i7eqb+7*+ uhx $1.2\,m^2$ 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 t65q7i:ssc(xh6fycn pfwd7 8 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 the3ls 3154zden2 ctohjw* yr 5an interior of the body to the surface. Assume2z cnra3 5ojyw41d ln5* s3het that the thickness of tissue is 4.0 cm, that the skin is at 34$^{\circ}C $ and the interior at 37$^{\circ}C $, and that the surface area is $1.5\,m^2$ Compare this to the measured value of about 230 W that must be dissipated by a person working lightly. This clearly shows the necessity of convective cooling by the blood.    W

  A house has well-insulated walls 17.5 cm thick (assume conductivity of airo) 2on3)uvazq) and arvoz u 2)n3oqa)ea $410\,m^2$ 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 af;r r )ix)rc)3r6rjgnt $220\,m/s$ 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 radiaj c1eww ,a j60ofvh( hq7may(,tion from the leaf to calculate how much water must be transpired (evaporated) by the leaf per hour to maintain a temperatur (jmw vay q,h0(ch7oe wjf,6a1e of 35$^{\circ} C$.    g/h

  An iron meteorite melts when it enters thef 2ai,w2:sfzjl.k f (a Earth’s atmosphere. If its initial temsaffwj:,f k.( 2ail2zperature 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 ys 9v. z/fij2tthe 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. 14–22)w7mb 3mm1gd)m)cf lf2, two people hit a soft rubber ball at a wall until they are about to drop due to dehydration and exhaustion. Assume that the 3l)fm1m)md2b 7 mfcwg 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 finals r1rc wss8tla0+b3 0l result 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 :bou0 fr/w10+8ma sic(q5awhvt;dwmheat by conduction and radiation at a rate of about 200 W. Estimate how long it would take for the body t(m0a85w wds/q 0t;m+:uov hfcwr bi1aemperature 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 in.qi,ryj: r:b/ l; jhlw the 50-gal (1lqwb.y/i hrlj r, ;::j85-L) water heater. This suggests that the tank has emptied and refilled with water at roughly 10$^{\circ} C$. (a) How much energy does it take to reheat the water to 50$^{\circ} C$? (b) How long would it take if the heater output is 9500 W?    s

  The temperature of the glass surface of a v5r19kwr uz +k60-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.    $^{\circ} C$