What happens to the work done when a jar of orange juice is vin/gq-ofp1(f omiprk6h i1 /i* gorously shaken?

When a hot object warms a cooler object, does temperature flow s.r)h dca: .xl nmy.sogar528between them? Are the temperature changes of the two obj.x .cmr.s :)as gohryln28a 5dects equal?

(a) If two objects of diff+x1a5 zf 7xlolerent temperatures are placed in contact, will heat naturally flow from the object with higher internal energy to the object with l1 l7lx xzaof+5ower internal energy? (b) Is it possible for heat to flow even if the internal energies of the two objects are the same? Explain.

In warm regions where tropical plants grow but the temperaturem3wlh/ mn +b4kor9fi+ may drop below freezing a few times in the winter, the destruction of sensitive plants due to freezing can be reduced by watering them in the evenim /on fkr+hi3+w49bmlng. Explain.

The specific heat of water is quite large. Explain why t4zx939nyj ai tw 5kw:lhis fact makes water particularly good for heating systemw :ja3in wlt949xk 5yzs (that is, hot-water radiators).

Why does water in a metal cantfhza kq7;h(-xv n7lq. een stay cooler if the cloth jacket surrounding the canteen is kept m -v7hqfkha7l;(.qz xn oist?

Explain why burns ca8 yswb1pv, 3okuw0 mx11+qlby used by steam on the skin are often more severe than burns caused by water at 100 p1vkybwo u08xs1 1lq w3+b,m y$^{\circ} C$ .

Explain why water cools (its tempe ihn*xi3.gzadsm2 s19b9jcx)rature drops) when it evaporates, using the concepts of latent heat and internal ene xmbngi)zxj32*a 9.hcs1 i9sdrgy.

Will potatoes cook faster ijbvuh+:gt :1v f the water is boiling faster?

Does an ordinary electric fan cool the air? Why or why not? If not, why udo f2 :nwt.zc4j bws7ona8h: )se it?

Very high in the Earth’s atmospheroyvp )wh(g(d *e, the temperature can be 700 $^{\circ} C$ . Yet an animal there would freeze to death rather than roast. Explain.

Explorers on failed Arctic expeditions ha/lh*t2.r7 ce fsk2 crzve survived by covering themselves with snow. Why would they do hsez r.cfrt72 /lk*2 cthat?

Why is wet sand at the beach cooler to watpo:n9g hhc43 a.pwl*lk on than dry sand?

If you hear that an object has “high heat content,” does thatskce td) e)9c; mean that its temperature is high? Explaecc; dk)st )e9in.

When hot-air furnaces are used to heat a house, why is it important that the c./,b 1d3anvsy8 zheere be a vent for air to return to the furnace? What happens if this vent3zy1e,d8 ac n/hvs. be is blocked by a bookcase?

Ceiling fans are sometimes rever,dy :l:twlqcs*x,: kbp3td w* v f6r-qsible, so that they drive the air down in one season and pull it up in another season. Which way sh ,b llwx :dvq k w6:cs,-3fp*:qdtty*rould you set the fan for summer? For winter?

Down sleeping bags and parkas arcept:- n r+6i2jsz nj+e often specified as so many inches or centimeters of loft, the actual thickness of the garment w:iz nt p+jrs2+6j-nechen it is fluffed up. Explain.

Microprocessor chips have a “heat sink” glued osz7a9vbk .bb 0ir/5m q2*w9j s.hcczme1 xdu :n top that looks like a series of fins. Why is it shap s9m *7ibqvx r9 ejdmbwaz5/u0c zc1b2:..shked like that?

Sea breezes are often encountered on sunny days at the shore o9y2o6;illztt ao3+ qq f a large body of water. Explain in light of the fact that the temperature of the land rises more rapidly than that lzt2;o+q3yitq6oa 9 l of the nearby water.

The floor of a house on a foundation underhgly de ,pl.27 which the air can flow is often cooler than a floor that rests directly on tdyllpge . 7,2hhe ground (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 readings are always taken with the thermometerp6 5e8d/l: bkf6)gyggvc k,o w in thwvlgfoyg)8ep 6 :/dg bk, 56kce shade.

A premature baby in an incubator can be dangerously cooled even when the airfua*e4 m+ mu ksct8s.1 temperatcms +. ae1f t4s8*ukumure in the incubator is warm. Explain.

Why is the liner of a thermos bottle silvered (Fk9m rff ohp211ig. 14–15), and why does it have a vacuum between its two war1p ok29m1ffhlls?

Imagine you have a wall that is veryjsou mjpw uwoz2h .9:vx5*-; 0ndowx/ well insulated — it has a very high thermal resisw0h */- :5duz;xuwm wojx.noo29 pvsjtance, $R_1$ 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:nq.o;)os 0 iprml1m8 e (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 ;m0oe. l)m iqr1pos8n, convection, or radiation? (b) Heavy curtains reduce which of these heat losses? Explain in detail.

A piece of wood lying in the S* 7i bu g-iaefuzi-nw,69xq z:un absorbs more heat than a piece of shiny metal. Yet the woo9xieaiw 7bzg:iufn-q6 z,u*-d feels less hot than the metal when you pick it up. Explain.

The Earth cools off at night much more quickly / 8y9,ceu/fm-fqlhc4wt,m k qwhen the weather is clear than wheq/m e4tkw-ch,f/yq8l ,c umf9 n cloudy. Why?

An “emergency blanket” is a thin shiny (metal coated) plastic fohwqqgua t 9ztf7t.t9;;:iw d(il. Explain how it can help to keep an it(ww; .d9 fu7qzi agttq:th9 ;mmobile person warm.

Explain why cities situated by th 26vvwamkj3 ,xe ocean tend to have less extreme temperatures than inland cities at the same latix, 6 k3m2ajwvvtude.

  How much heat (in joules) is required to raise the temperature of 30.0 kg of watf7h6s8h c69ns+ (xn8coy lr pber frol 8xcoh h7c6yb6 sr(+ns8fp 9nm 15 $^{\circ} C$ to 95 $^{\circ} C$ ?    $ \times10^{7 }\,J$

  To what temperature will 7700 J of heat raise 3.0 kg of water tj duom,o:6w 0ehat is initially at 10.00,6muowd e :oj $^{\circ} C$ ?    $^{\circ} C$

  An average active person consumes 2v(,lt8hkal *mfx kccxnm1/z:i0he6 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 hern(f9l(iqy;uvwq g )etp+n mc/9v .a.at in the British system of units. One Btu is def(gv a 9np.uqmyrq. f+ni )v(ecwtl9;/ined as the heat needed to raise 1 lb of water by 1 F $^{\circ} $ . Show that
1Btu = 0.252kcal=1055J

  A water heater can generat3vlq7fafoe-b f3 t57 ae $32,000\,kJ/h$ 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 how3pqs -ztk4p -1 oa lyl1j;(nnn long it will take to heat a j-lk 1znnys tn3ql(p;ao 4-p1 cup of soup (assume this is 250 mL of water) from 20$^{\circ} C$ to 60$^{\circ} C$ .    min

  How many kilocalories are generated when the brakes are used to g8dt-h *f .-j)rq gajbbring a 1200-kg car to reajdbgrf. *8t g-- qj)hst from a speed of $95\,km/h$ ?    kcal

  An automobile cooling diw1*x ( b(alp y/.hn04sjb30zfw fau system holds 16 L of water. How much heat does it absorb if its temperature risesx 0a .j3wnpywb(0 4h* aiuzl1ff(b/ds from 20$^{\circ}C $ to 90$^{\circ} C$?    $ \times10^{ 6}\,J$

  What is the specific heat of a metal substance if 135 kJ kd0.v,x kt -,6uuu d6((ttunyrtzpb* of heat is needed to raise 5.1 kg of tb v6utdyx0 udu k6tp(n( tkru*z-, .,the metal from 18.0$^{\circ}C $ to 31.5$^{\circ} C$ ?    $J/kg\cdot\,C^{\circ} $

  Samples of copper, aluminum, and water experience the same temperaturen )v-nwt.gc k: rise when they absorb the same amount of heat. What is the rat .nk ntv)cgw-:io of their masses? [Hint: See Table 14–1.]$m_{Cu}$ : $m_{Al}$ : $m_{H_2O}$ =    :    :   

  A 35-g glass thermometer rnd 9v1eu-m5w peads 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 ao ;gwf1v q iwc6qs-1(bt 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 (ma:a 7 bjkzbmof /i:r:;rss = $0.4\,kg$) 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 heate-yln v+ 0;gk,hb v-mwnd 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 brinj c;+z+g )lx e0o:m7m;cgcom yg to a boil 0.75 L of water initially m+cgc o;jc; ozye+07x:)mgml 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 3ij z8rtpxc fhzqu)6q:*5,b+bv* pfh from the following 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 0.725 kg and is placed in 2.00 kg of water contained in an aluminum calorimeterv* * p5fib +8pjzb)f x,qq6czrhh3 :tu 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 m mvj2w0 03jl;upuhaq7xqgemy1 2 9t *at 180$^{\circ} C$ is placed in a 95-g aluminum calorimeter cup containing 250 g of glycerin at 10$^{\circ} C$ , the final temperature is observed to be 38$^{\circ}C $ . Estimate the specific heat of glycerin.    $J/kg \cdot C^{\circ} $

  The 1.20-kg head of a hammer has a spegkeqwf* .nh9 8ed 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 objecxwuw*u b6+e+p njh,(657 scqqpt mpl0t is defined as the amount of heat needed to rai qswujc+q 7 0p(um65nthp,lpe6wb*+xse its 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 that is initiallalh/uu6crme 5 ( l6kq6y at 20$^{\circ} C$?    $ \times10^{6 }\,J$

  A 0.095-kg aluminium sphere is dropped from the roof of a 45-m-high f th/n q0l*p/our4 gl5building. If 65% of the thermal energy produced when it hits the ground is absorbed by the sphere, what is its telqonu lg/0 tr/* h45fpmperature increase?    $C^{\circ}$

  During exercise, a person may give off 180 kcal of heat iz q)x1, oqap5kn 30 min by evaporation of water from the skin. How much water has been lost?)zq kpaxo 5q,1    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 con qs:4df86pldt tainer of liquid nitrogen. How much nitrogen evaporates if it is at its boiling point of 77 K and has a 86:lsfddpq4tlatent 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 freezer at;inw2(. rox ov -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;2f y.gyq -pbu,r raf1 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 k u:ke1lu0qyi p:2mp74i be re,g8 5ycconsumes 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 i284ee, 7iqkl5eyrg1 uk:pycu0bm: p the rider use during the ride? (Since the efficiency of the rider is only about 20%, most of the energy consumed does go to heat, so our approximation is not far off.)    kcal

  What mass of steam at x 6,1flheta + )9mqkcp100$^{\circ} C$ 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 2zy-bv7-b*ew nnkao cyu7s a392dw* i mercury 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 /ignm f 676nqlat $250\,m/s$ 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-skatery,s2gnht 0p;)sy r,,gapvx e :+s. mth 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 3czbm9g pw2:zforensic 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 temperatuzb29gc 3 mwz:pre (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 kep- 4x6-oqsif5 wjbb ,crtp8ql *t 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 i4ljyd 2zjqf9*tfv e) )n Example 14–10, assuming that there are strong gusty winds and the extel f dz)fq)e4*vj29yjt rnal temperature is -5$^{\circ} C$   $ \times10^{4 }$ W

  (a) How much power is radiated by a tungsten sphere (emissivityf tun ;ukd671 1i9kefr $e\,=\,0.35$) 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 f8- 04j ev ptqjxdzl19(gk*hzz rom the blood9 q-ej4z*1j8kv pxzl hz( dt0g capillaries beneath the skin to the body’s surface area of $1.5\,m^2$ If the temperature difference is 0.50 $C^{\circ} $ , estimate the average distance of capillaries below the skin surface.    $ \times10^{-4 }$ m

  Two rooms, each a cube 4.0 m per side, share o n/l9l)hxk6aa 12-cm-thick brick wall. Because of a lnoa/l9) hx6knumber of 100-W lightbulbs in one room, the air is at 30$^{\circ} C$, while in the other room it is at 10$^{\circ}C $. How many of the 100-W bulbs are needed to maintain the temperature difference across the wall?    bulbs

  How long does it take the * 9v-zynpbkm 8Sun 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 saxeq-)v95j/) ws6l tb +wbobwz+to (rg me length and cross-sectional area are attached end to end (Fig. 14–18). The copper end is placed in a furnace maintained at a constant temperature of brst ov/9 5q+)- (lw ez6)w wbbojxgt+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 whirwu;z,-r5o bqch the whole Earth receives energy from the 5 zruorwqb,-; 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 omb dds3+p;,k df heat, which is dissipated through a glass bulb that has a radius kmspd3 ,bdd; +of 3.0 cm and is 1.0 mm thick. What is the difference in temperature between the inner and outer surfaces of the glass?   $^{\circ}C $

  Suppose the insulating qualities of the wall of a tz 7)towqii8)qqov(7eoru+:b v3 dq +house come mainly from a 4.0-in. layei 77 irt3b8(ev)uqt zwo+:qoqd)qo+ vr 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 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 glas1,wcp d 58ljchxn)j7r2 b y7rc*,lbwj s separated by an air space, Fig. 14–20. (a) Show w1p jc7hdclw*,r,7b) 2j5jlycxb8r nthat the rate of heat flow through such a window by conduction is given by
$\frac{Q}{t}$ = $\frac{A(T_2-T_1)}{l_2/k_1+l_2/k_2+l_3/k_3}$,
where $k_1$,$k_2$ and $k_3$ are the thermal conductivities for glass, air, and glass, respectively. (b) Generalize this expression for any number of materials placed next to one another.

  Approximately how long should it take 11.0 kg of ic bhlt . +t4.f8om;k+qk4hdv39cwzjw ve 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 yi2l*6(jnhqjjjri0sp-t z+);l * pjc0.20 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 therr/p+j)6n w 4 lahuobv/*oufi:mal energy is contained in the world’s oceans, estimate the heat liberated when a cube of ocean water, 1 km on each side, is cooled by 1 K. (Approxima*/rj): u /aphlow4nibv 6fou+te 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 bloslb 2rwi/c +8dvigx cx6,nxr e3(41wdck of wood with a mass of 1.05 kg. The block and imbedded 3 ,d wi+8x 2vi(/rcwxb6ls4 egnxr1cd 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 radiated into space by the Sun, assuekp1dg(bl(d6l(rpv a1)w)7m; jtk fj ming it to be a perfect emitter aept6vmj rfg1 ()1b7jdw()l( ld akkp;t $T\,=\,5500K$ 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 2ouhg( )bn :hnmay 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 boult* f7dm2kn oe(der rolls 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 heat generated remains in the ro t7 n*(kdo2fmeck.    $C^{\circ} $

  A 2.3-kg lead ball is dropped into a 2.5-L insulated pail of water3(: f c+zywvls initially at 20l+v: 3z s(wcfy.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 5o 5 oc-ar1h/sdi(yvr ared cr v(rs5hoi1/yo5-aa $1.2\,m^2$ 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 metaboli1zm9l.rdc.2 o;u bxzhr3 n;ehxaeh0 / sm 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 conds . zy :9v2whn*btz5kructed from the interior of the body tozsz*ryh 92t:nv.5w kb the surface. Assume 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 wutu)/z qywf,:hge 81galls 17.5 cm thick (assume conductivity of air) and area :h/fuqe8g w yz gu,t)1$410\,m^2$ 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 ic:/++arz omu2jg* bnat $220\,m/s$ 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 parztio1.tzj ;* et (a) in Problem 58, take into account radiation from the leaf to calculate how much water must be transpired (evaporated) by the leaf per hour to maintain a temperature oft.tjez1z*oi ; 35$^{\circ} C$.    g/h

  An iron meteorite melts when it entet/ f3 :mulh 36a,fhehers the Earth’s atmosphere. If its initial temm 3 th3flh/,: a6eehufperature 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 crusi ;avb.wdnd:+kpfc*5v 8sq z-t 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 tbli *3 5 ywejg:;.kic(Fig. 14–22), two people hit a soft rubber ball at a wall until they are about to drop due to dehydration and exhaustic;ey i.j 53igw tkb*:lon. 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 fina7/4fqkz9 dpzqu8gcn*n yt7x (l 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 heat by conduction and radiation a8jwj 3f meg.9et a rate of about 200 W. Estimate how long it would take for ej.meg9 fjw83 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 dishwashpu* u,ehm355 w rvmoud- nq3cv) uf13uing, there is “no hot water” left in the 50-gal (185-L) water heater. This suggests that th)v3m-rm5,fuc 53 p* ovdhq3uw 1 uenuue 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 mx dt4;)2tcgdc h9x1ar nzgtm .u,9-zsurface 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.    $^{\circ} C$