What happens to the work done when a jar of ob1h )x9vx5z vjrange juice is vigorously shaken?

When a hot object warms a cooler object, does te2+5 to+pxlk mymperature flow between them? Are the temperature changes of mx+o2y+5 pktl the two objects equal?

(a) If two objects of different temperatures are placed in con q(lf)h:pwq )gj p+ go+k4r7cltact, will heat naturally floqq 4cw+lf:+plh) pgkgo)(rj7 w from the object with higher internal energy to the object with lower 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, ps9 *e3nzr.zhh-zmj grow but the temperature may drop below freezing a few times in the winter, the destruction of sensitive plants due to freezing cn,z.zz9*r hj3smh -ep an be reduced by watering them in the evening. Explain.

The specific heat of water is quite large. Explain why this fact makes wate 1 1p rvd5,8truh9yzf0ld(xwrr particularly good for heating systems (that is, hot-water r 119tr rxufrv0dlwz,5y (hdp8adiators).

Why does water in a metal canteen stay cooler if the cloth jacket surroundingru t:22q7fu qq the canteen is kep2t:rqq uqu 2f7t moist?

Explain why burns caused b9tg o8i,plmwe/)u j)d y steam on the skin are often more severe than burns caused by water atdj9to m/8elp i w,g))u 100 $^{\circ} C$ .

Explain why water cools (its temperature0s hsw)k t(pcar5l /k/xv42 lj drops) when it evaporates, using the concepts o()cwk 54lh/a/vp 2stksl 0rj xf latent heat and internal energy.

Will potatoes cook faster if the water is boiling fast36+u6 lniev (z 6aw7 ypaknv+aer?

Does an ordinary electric fan cool the air? Why o4l;9 dh.9t.rg.b*lj8-ua0n p enjcotnw i, dpr why not? If not, why use it?

Very high in the Earth’s atmosphere, the temperature can be do 3,hio::g xg700 $^{\circ} C$ . Yet an animal there would freeze to death rather than roast. Explain.

Explorers on failed Arq /2rv :lx6fwrctic expeditions have survived by covering themselves with snow. Why would they xr6fw: lqv2r/ do that?

Why is wet sand at the beach cooler to walk on than dry sandyq5h7ds4z hub2cg1b 3 ?

If you hear that an object has “highd-h:u wjccslggop:r7.k8 / x9 up+;cre w0d+q heat content,” does that mean that its temperature ispdp 8rxccd.o+jweuh rcsuq:/7; k gl +w0:g9- high? Explain.

When hot-air furnaces are usea*kdtd* 5 gkx1d 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 blocked by a bookcdxd5 k*ga1kt*ase?

Ceiling fans are some bhqq -+9yj7astimes reversible, so that they drive the air down in one season and pull it up inj9+y7s a hq-bq another season. Which way should you set the fan for summer? For winter?

Down sleeping bags and parkas are often specified as so many inc2 pxkp52+kvt hhy li m6fgui236hh0b5 hes or centimeters gupkiyklb52m x66f2+ h0hti 2h3 h5vpof loft, the actual thickness of the garment when it is fluffed up. Explain.

Microprocessor chips have a “heat td)okl4 gc/un)i,wn-sink” glued on top that looks like a series of fins. Why iskn,-/uigdntlc) )4o w it shaped like that?

Sea breezes are often encountered on sunny days at the shore of a large body oea)dwg;aayf3b1 k)h :f water. )3 g):a afkd1ae ;hbywExplain in light of the 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 the air can flow is often coz8v2imx5j( n sn ib/ifql (,+9iyxu3foler than a floor that rests directly on the ground (such as a cois93 vbu/mxzqixinyf+f8 n((25 ji l,ncrete 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 at7qs x y/-,ya fs8h9fbre always taken with the thermometer in the sh98q,htaysf/fby-7 sxade.

A premature baby in anx -qu.zmou (c w.f3iv)5,1f )fhzg lav incubator can be dangerously cooled even when the air temperatu, vc-z( mavfo.q)flf 53.uxw1hi zg) ure in the incubator is warm. Explain.

Why is the liner of a thermos bottle silvered (Fig. 14–15), and why do i/xlt 8ip+8jzes it have a vacuum between its twoxj/8l z8p+ iit walls?

Imagine you have a wall that is very well insulatea l:nd,l gl;sc/m 9)wed — it has a very high thermal rem,dsna lcl9 ewlg ):/;sistance, $R_1$ 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) vd-82vhsye+h kentilation around edges; (2) throu +vysed k8hh2-gh 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 detail.

A piece of wood lying in t 3kmapy:2 1p8qxli 5znyh9jn4he Sun absorbs more heat than a piece of shiny metal. Yet the wood feels le n29lm8kih qp15 ynyxp4:3zj ass hot than the metal when you pick it up. Explain.

The Earth cools off at night much more quickly when the weather is clear thlhgeg )0p gl;2dpb/i gxa)a,rc:;h q,an when cloudy 2gi:g,;q/pal r0;hgxedbgah,)cl) p . Why?

An “emergency blanket” is a thin shiny (metal coated) plastic foil.t3:0oxi -0obeuya4 c r,xk;el Explain how it can help to keep an immobile persokcao u4xeol,0t: b-x ire 3y;0n warm.

Explain why cities situated by the ocean tio3,won.u 0aa end to have less extreme temperatures than inland can0oo i,u.3a wities at the same latitude.

  How much heat (in joules) is required todfysv+ .+ if(n raise the temperature of 30.0 kg of water fromds+n f.yi(v+f 15 $^{\circ} C$ to 95 $^{\circ} C$ ?    $ \times10^{7 }\,J$

  To what temperature will 7700 J of heat , eg+vd3ko3p4nkagy7raise 3.0 kg of water that is initially at 10.pd33o7+4 g kknagv,ey 0 $^{\circ} C$ ?    $^{\circ} C$

  An average active person consumes about 2500 Cal a day. 86vsjl2aai d5
(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 the2og n178jcnn3ox13lth w ;-a o.gj vzl British system of units. Onxon217.ltgo-3 hw; 8lnazvo g ncj1j3e Btu 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 generatelg2gyb4 -5vk* lh pnd+h8;nwn $32,000\,kJ/h$ 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 wil . o73/5d9oc )qiwjlnwpz y5spl take to heat a cup on.wjyoiw3dsp7 95pz)5 /oqlcf soup (assume this is 250 mL of water) from 20$^{\circ} C$ to 60$^{\circ} C$ .    min

  How many kilocalories are genf3,:ao 8symh zapk0cr :,lr a5erated when the brakes are used to bring a 1200-kg car to rest from , o8fmpsaca:0z hl3ar5k,ry :a speed of $95\,km/h$ ?    kcal

  An automobile cooling system holdshj: +dj 0v(nhdz,5coc 16 L of water. How much heat does it absorb if its temperathccj:z d v,n(hjdo5 +0ure rises from 20$^{\circ}C $ to 90$^{\circ} C$?    $ \times10^{ 6}\,J$

  What is the specific heat o en3 5bqrs h0jnazwh t30lp:fo9t4/z;f a metal substance if 135 kJ of heat is needed to raizjpe 54lbt:/3rh;oz stf30qnanh w09se 5.1 kg of the metal from 18.0$^{\circ}C $ to 31.5$^{\circ} C$ ?    $J/kg\cdot\,C^{\circ} $

  Samples of copper, alumibe)69g-g v bkynum, and water experience the same temperature rise when they absorb the same amount of heat. What is the ratio of their massb-e)g 9kbvy6g es? [Hint: See Table 14–1.]$m_{Cu}$ : $m_{Al}$ : $m_{H_2O}$ =    :    :   

  A 35-g glass thermome +6wd 9fb3aux y95jg rdk28h2cz gapm,ter reads 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 cot 8b;(dd7akc5 y vg*+ckx9 s em:npv0cpper 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 kda;zgo/6 l skq p),9x9acys*(mass = $0.4\,kg$) 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 subs gfjof6ie+y0kxi.;* sh,*wbb tance is heated to 330$^{\circ} C$ and then plunged into a 105-g aluminum calorimeter cup containing 165 g of water and a 17-g glass thermometer at 12.5$^{\circ} C$ . The final temperature is 35.0$^{\circ} C$ . What is the specific heat of the substance? (Assume no water boils away.)    $J/kg \cdot C^{\circ} $

  How long does it take a 750-W coffe8xf *l upj;9laepot to bring to a boil 0.75 L of water initiallx89la*;jl fupy 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 c08:snz uphin7n . fh a6xk:2(zcyr hk)andy from the following measurements. A 15-g sample of the candy is allowed to dry before putting it in a bomb calorimeter. z y8 (xrhzah6fk:7 0pns nc ).:n2hiukThe aluminum bomb has a mass of 0.725 kg and is placed in 2.00 kg of water contained in an aluminum calorimeter cup of mass 0.624 kg. The initial temperature of the mixture is 15.0$^{\circ}C $ , and its temperature after ignition is 53.5$^{\circ} C$ .    Cal

  When a 290-g piece of iron s(t48bqfdjie.,da1n) et u.mat 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 speed ofrbr+ )txh(u2 *4rufd6eg gqe. $6.5\,m/s$ 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 t 0i)3j7eixyjr he amount of heat needed to raise its temperature ri73 e 0xjyij)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 initiallylq:j7w0pm e;i at 20$^{\circ} C$?    $ \times10^{6 }\,J$

  A 0.095-kg aluminium sp p;.4b ewb/a,ad 6joyihere 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 the sphere, what is its temperata ey, dwb/aob;.6 p4ijure increase?    $C^{\circ}$

  During exercise, a pers pmytf+he6kq.ky736nb , e jz852ojezon may give off 180 kcal of heat in 30 min by evaporation of water from the skin. How much+87 nzyp6e5 f.yeo, mj3 6ztekjh qk2b 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 mel2xlr)p( :lxvy ting point is dropped into an insulated container of liquid nitrogen. How much nitrogen evaporates if it is at its boiling point of 77 K and has a :2xxlv)ry lp (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 tu0 7flx7:op9*opz n unhe 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 knk ,q*.p-gpsy g 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 the span of fo9;t f tbdr:oq9 )o cm.jqr1v.our hours. Making the approximati;rdvq fjoro:9q b1mc .t. t)o9on 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 our approximation is not far off.)    kcal

  What mass of steam at 1g 3n0y ni9-b rhs)n0fllr*g :x00$^{\circ} C$ 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 merc,afd(y e2a(a aury 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 travelo 1 whg* tzu)((h,qp-+kfaxippgds3/ing 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 muhu z0d tc)/.doving 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-hytl ;p7 lk6d forensic investigator notes that the 8.2-g lead bullet that was stopped in a doorframe apparently melted completelyld-6hl 7py; tk 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 alumig .r:.dim ( ,m l1 ogxpk868gqtcic1gxnum rod with 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 co1mvdr6(z4*pq1p;u j. emp 8rbqqff sy36 if y4nduction in Example 14–10, assuming that there are strong gusty winds and the externa46qpvd*fymr68 f1;4 b 3 r zf1(ejpi qyqmp.sul temperature is -5$^{\circ} C$   $ \times10^{4 }$ W

  (a) How much power is radiated by a tungs(0-j6 ckaqwv ). jqyf(y:ce tkten 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 from the bl rqg*pbtoz 2oop/b*a a;82vd;*hb 1okood capillaries beneath the skin to the body’s pvzb;8o qrta1kb ;ao2* *2d goh*pb /osurface 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, sharq7zk:9fm c j+ce a 12-cm-thick brick wall. Because of a number of 100-W lightbulbs in one room, qmj:czf97+ k cthe 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 bloc(6pv20qkgn k gk 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 lengt:v(gpvq65 vg tq4x5rb h and cross-sectional area are attached end to end (Fig. 14–18). The copper end is placed in a furnace maintained at a constant temper gqv 5p:v4rbx5gq t(v6ature 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 consteb((oizb( m .want, estimate the rate at which the whole Earth receives enerzo( embib( w(.gy 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 heat, which is dissipatep/ bc.cuj;9cad through a glass bulb that has a ra/ap9uc j;cc.b dius 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 qualpsfkv;pxu ,v/)wzr y-b;o +.fities of the wall of a house come mainly from a 4.0-in. layer of brick and an R-19 layer of i .pkwvsb,u;zxrfp;o-v ) / f+ynsulation, 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 yei 8+ xi0(bybtwo panes of glass separated by an air space, Fig. 14–20. (a) Show that the rate of heat flow through such a b0yiiby8+( xewindow 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 s lysc/50*mqx,0 r u)qiqtr,ffhould it 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 9dqnp1eyf 9q-.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 is contained in the woo6ejmxz* /:)rj jn3c (esw 8world’s oceans, estimate the heat liberated when a cucjes: )zj(r j wx38w6o m/noe*be 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 fixed block of wood with a masu)*nc*gn(a iwr ctqa aoj8 .nr,k .-7vs of 1.05 kg. The block and imbedded bullet together absorn ,-n inaoatr.vcc ()u*8wjk*r7ag. q b 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 bum(3yrz4l uui 1 x4rtu*bg3 i6y the Sun, assuming it to be a perfr iilubr*4(y4uu 3gzxt 6mu13ect 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, a 70-kg perrqr3; f9z h3 jo/at 9k6emxyx3son 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 2mz+;i pnh89j h i+de+a9lwi 8oce+ vqthe 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 rhea+ n9o ehciv lqz iw+9jp8+i28d+m;emains in the rock.    $C^{\circ} $

  A 2.3-kg lead ball is dropped into a 2.5-L insu d0i vi-e0byr,6jnv1slated pail of water initially at 20s0v1-bn 0ridv6i ,y je.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 surf yrdb l 7i4x/)r*ivot2ace areaob2iv7dl*yr4x t i) r/ $1.2\,m^2$ 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 aboutcpm*f xeu5:manir.9yy k6p:z 1u-no0 arn/5v $950\,kcal/h$ 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 conducte61i1-mvp+ qt)uw zfrxd from the interior of the body to the surface. Assume that the thickness of tissue is 4.0 cm, tmu1 6zpxfvi-w)rqt+ 1hat 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 conductu c9ucd5-qc:nivity of air) and a: dnccu-9q u5crea $410\,m^2$ 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 travelinglis-6zbhaqoq 35 5kp / 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 Problem 58, take intocyp7xqf.oh 6/ account radiation from the leaf to calculate how much water must be transpired (evaporated) by the leaf per /6o cqypfh 7x.hour to maintain a temperature of 35$^{\circ} C$.    g/h

  An iron meteorite melts when it en .pxre9xn.+ nqd jf3o52c a(uo(m9:6 tkrvfknters the Earth’s atmosphere. If its initial temperature was -1(f.k vo+ 6e k2a5( 9c:pxq.xormtfnn dujr39 n25$^{\circ} C$ outside of Earth’s atmosphere, calculate the minimum velocity the meteorite must have had before it entered Earth’s atmosphere.    m/s

  The temperature withr08ynqkb8o y3av , fy-o 1c/rzin the 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 squasm1v ig ufxfoih1l17zn1t8;;z s u:gw2 r0cyt*h (Fig. 14–22), two people hit a soft rubber ball at a wall until they are about to drop due to dehydration and exhaustion. Assume that the ball hits the wall at a velocity :;zlgityx;c*8 iogh1tu m1nuzv rf w0 s72f11 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 resuljr v-:y ykg-zp6+m+dbcm w2z.*a/ ghht 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 atukuh -q:v e/0j a rate of about 200 W. Estimate how long it would take fo: e- juvhq/0kur 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 “ov+j)agt ehu/(+b8 p7 /qiqwdt8h,d fno hot water” left in the 50-gal (185-L) water heater. This suggests that the tank has emptied and refilleoi / )+7afgh,ebj/ vth8p(8 ddu twqq+d 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 lightbulb -/y jqqul03e t5t19b e8tmh csis 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.    $^{\circ} C$