Fill in the missing particles or nuclei: jsrmn/u1: (lo
(a) $\text{n} + _{56}^{137}\text{Ba} \to ? + \gamma$
(b) $\text{n} + _{55}^{137}\text{Cs} \to _{56}^{137}\text{Ba} + 2?$
(c) $_{92}^{235}\text{U} + \text{n} \to _{38}^{90}\text{Sr} + ? + 3\text{n}$
(d) $? + \text{d} \to _{79}^{197}\text{Au} + \alpha$
where d stands for deuterium ($_{1}^{2}\text{H}$).

The isotope $_{15}^{32}\text{P}$ is produced by the reaction: $? + \text{n} \to _{15}^{32}\text{P} + \text{p}$. What must be the target nucleus?

When $_{11}^{22}\text{Na}$ is bombarded by deuterons ($_{1}^{2}\text{H}$), an $\alpha$ particle is emitted. What is the resulting nuclide?

Why are neutrons such good projecyc sf(.g r y:m+oh3wh4tiles for producing nuclear reactions?

A proton strikes a $_{10}^{20}\text{Ne}$ nucleus, and an $\alpha$ particle is observed to emerge. What is the residual nucleus? Write down the reaction equation.

Are fission fragments 7l7ljjwgjti., cikj i ;(4w5 k$\beta^+$ or $\beta^-$ emitters? Explain.

  If $_{92}^{235}\text{U}$ released only 1.5 neutrons per fission on the average, would a chain reaction be possible?  ----待选择----yesno 
If so, what would be different?

$_{94}^{238}\text{Pu}$ releases an average of 2.5 neutrons per fission compared to 2.9 for $_{94}^{239}\text{Pu}$. Pure samples of which of these two nuclei do you think would have the smaller critical mass? Explain.

The energy from nuclear fission appears in the form of thermal energy - but 2j1pm,dhvkvw zc f 9.c. 49yexthe thermal ene.c,d 24vj fkx9w1. p z9yvcmhergy of what?

The energy from nuclear fissionn+v8-uicbw8ub9w6tz uv ,r9 ubx:4mj appears in the form of thermal energy - but the t8tcu4vbbr x wumz6 8un9:ui b+j-9 w,vhermal energy of what?

Why can't uranium be enrichedxm8) t( cvi+u- y7kwsv by chemical means?

How can a neutron, with practically .jidv/ dhhgk ag,*.2nno kinetic energy, excite a nucleus to the extent sg.v*kdh,i j. adn/ h2ghown in (Fig. Below)?

Why would a porous blo cp vlkxg83+o8ck of uranium be more likely to explode if kept under water +8pcg8xk 3vol rather than in air?

A reactor that uses highly enriched uranium can use ordinar+ 1buq h*xkwc/y water (instead of heavy water) as a moderator and still have a self-sustaining ck* ubh1w/qc+ xhain reaction. Explain.

Why must the fission pny5 . ezn 11d5m6xuwsgrocess release neutrons if it is to be useful?

Discuss the relative merits and disadvantages, incl5;i2tifwnefogg 2qqb:fvtgr* t j0(3 6:h1m suding pollution and safety, of power generation by fossil ojt(i3h22r g 1;qs:f*m:ibf0wf5tvnqge gt 6fuels, nuclear fission, and nuclear fusion.

What is the reason for the "secondary system" in a nucleavcfv a ly:*2(lr reactor, (Fig. Below)? That is, why is the water heated by the fuel in a nuclear reactor not used directlyvca llv:(y2 *f to drive the turbines?

Why are neutrons released in a fission rm,)))qy9sexy8 uxgux wg 1l(jeaction?

Why do gamma particles penetrate matter more eas9 0ry):rk of; jjq uu90mcrd 9x3tfbe6ily than beta particles do?

A higher temperature is required for deuterium-deuterium ignition than for de5noy5 wr, efjtds*w96h7plg 6uterium-tritium.jd* 6t ,le5759gnwrhp oy6 fws Explain.

Light energy emitted by the Sun an4o7kxm fv7n75 s nbu9od stars comes from the fusion process. What conditionoxnv5k u4m9sf 77nb7os in the interior of stars make this possible?

How do stars, and our Sun, maintain confinement of t+fmiyaawg ;vg- 9 r 0*qkhq4n5he plasma for fusion?

What is the basic diffazj70 1z)hc(z.*8o spnrt oazerence between fission and fusion?

People who work around metals that emit alpha particles are trained that thedbqjt /i n4c:o15wd 1sre is little danger from proximity or even touching the material, but that they must take extreme precautions against ingesting it. Hence, there are strong rules against jcns wbq1/odt1:4i 5d eating and drinking while working, and against machining the metal. Why?

Why is the recommended maximum radiation dose highe/c+js8*x gxkt wbvu; .r for women beyond the child-bearing age than for g *sxvt8;ux cjwb+/ k.younger women?

Radiation is sometimes used to sterilize medical supplies yg+n 5bcg t4g:and even food. Explain how ig nt5y:4 ggc+bt works.

What is the difference between absorbed dose and effective dose? What are wvp (yktva0w9m)3lu3avb d3 - the SI unita m0 dkt39p-luvb wyawv v33)(s for each?

How might radioactive tracers be used to find a leak x mrt6)ju u )u2tt7wg-,a1yct in a pipe?

Natural aluminum is all kv ar+ 3qs)jt1$_{13}^{27}\text{Al}$. If it absorbs a neutron, what does it become? Does it decay by $\beta^-$ or $\beta^+$? What will be the product nucleus?

Determine whether the /wtc5vf:er+*ub6hjyoe u, by /. 3dulreaction $_{1}^{2}\text{H} + _{1}^{2}\text{H} \to _{2}^{3}\text{He} + \text{n}$ requires a threshold energy.

Is the reaction $\text{n} + _{92}^{238}\text{U} \to _{92}^{239}\text{U} + \gamma$ possible with slow neutrons? Explain.

  Does the reaction $_{3}^{7}\text{Li} + \text{p} \to _{2}^{4}\text{He} + \alpha$ require energy, or does it release energy? How much energy?    MeV

  Calculate the energy relb kaut5fu20/4 +wufrueased (or energy input required) for the reaction $_{5}^{10}\text{B} + \text{p} \to _{3}^{7}\text{Li} + \alpha$.    MeV

  (a) Can the reaction (yft)h z(pu jq2jk9h )$_{11}^{23}\text{Na} + \text{d} \to \text{n} + _{12}^{24}\text{Mg}$ occur if the bombarding particles have 10.00 MeV of kinetic energy? (d stands for deuterium, $_{1}^{2}\text{H}$)
(b) If so, how much energy is released?    MeV

  (a) Can the reaction s w y0jrpe67krt2v7fbv j(*b 5$_{3}^{7}\text{Li} + \text{p} \to _{2}^{4}\text{He} + \alpha$ occur if the incident proton has kinetic energy = 2500 keV?
(b) If so, what is the total kinetic energy of the products?    MeV

  In the reaction $_{8}^{18}\text{O} + \text{p} \to _{9}^{18}\text{F} + \gamma$, the incident $\alpha$ particles have 7.68 MeV of kinetic energy.
(a) Can this reaction occur?
(b) If so, what is the total kinetic energy of the products? The mass of $_{9}^{18}\text{F}$ is 16.999131 u.   MeV

  Calculate the Q-value for thaa:d 803kgn4z6qxf xv1)d ukbe "capture" reaction $_{2}^{4}\text{He} + _{4}^{9}\text{Be} \to _{6}^{12}\text{C} + \text{n}$. Q =    MeV

  Calculate the total kinetic energy of the p(-a b vkxmcn4pil442 sroducts of the reaction $_{6}^{12}\text{C} + \text{d} \to _{7}^{13}\text{N} + \text{p}$ if the incoming deuteron (d) has $KE = 36.3\ \text{MeV}$. $KE_{\text{total}}$ =    MeV

  Radioactive $_{6}^{14}\text{C}$ is produced in the atmosphere when a neutron is absorbed by $_{7}^{14}\text{N}$. Write the reaction and find its Q-value. Q =    MeV

  An example of a "strikk(dolg )nfb:l-6, gxpping" nuclear reaction is $\text{d} + _{3}^{7}\text{Li} \to \text{X} + \text{p}$.
(a) What is X, the resulting nucleus?
(b) Why is it called a "stripping" reaction?
(c) What is the Q-value of this reaction? Is the reaction endothermic or exothermic? Q =    MeV

  An example of a "pick-up" nuclpmt 6hou1u:2 dt urh6.ear reaction is $_{1}^{2}\text{H} + _{6}^{12}\text{C} \to \text{X} + \alpha$.
(a) Why is it called a "pickup" reaction?
(b) What is the resulting nucleus?
(c) What is the Q-value of this reaction? Is the reaction endothermic or exothermic?Q =    MeV

  (a) Complete the following nuclear react88w 5rwm1jj61n mv0chto7j ision: $\text{p} + ? \to _{16}^{32}\text{S} + \gamma$.
(b) What is the Q-value? Q =    MeV

  The reaction $_{9}^{19}\text{F} + \text{n} \to _{9}^{20}\text{F} + \gamma$ requires an input of energy equal to 2.453 MeV. What is the mass of $_{9}^{20}\text{F}$?
$m_{^{18}_{9}F}$ =    U

  Calculate the energy released in the fission reactionha) uc7.qxyg wbp u//c4gja76 $_{92}^{235}\text{U} + \text{n} \to _{56}^{141}\text{Ba} + _{36}^{92}\text{Kr} + 3\text{n}$. Use Appendix B, and assume the initial kinetic energy of the neutron is very small. Q =    MeV

  What is the energy released in the fission reaction of Eq. 31-4? (The masses of 3pxdep -n 7g(wturj4 f(cmf 06rf 03g4wm7-(efpdnt 6 cxj (pu$_{56}^{140}\text{Ba}$ and $_{36}^{92}\text{Kr}$ are 140.914411 u and 91.926156 u, respectively.) Q =    MeV

  How many fissions take place fieky.9zd0il17sbh:le7 j/71gjei k per second in a 200-MW reactor? Assume 200 MeV is released per fission. P = j1l 9/ikslef0z:k h7eie7j1 bdg.7yi   $\times 10^{13}\ \text{reactions/s}$

  The energy produced by a fission reactorh6:yt4h u5wb w is about 200 MeV per fission. What fraction of the rest mass ofyb w4 :utw6h5h a $_{92}^{235}\text{U}$ nucleus is this? The ratio is about $\approx 1 : $   

  Consider the fission reahn-jy (3 s:ysjfpq+xyex915 fction $_{92}^{235}\text{U} + \text{n} \to _{51}^{133}\text{Sb} + _{41}^{98}\text{Nb} + ?\text{n}$.
(a) How many neutrons are produced in this reaction?   
(b) Calculate the energy release. The atomic masses for Sb and Nb isotopes are 132.915250 u and 97.910328 u, respectively. Q =    MeV

  How much mass of $_{92}^{235}\text{U}$ is required to produce the same amount of energy as burning 1.0 kg of coal (about $3 \times 10^7\ \text{J}$)?    $ \times 10^{-7}\ \text{kg}$

  Suppose that the electric average pow/+oi3v0 lwd zoer consumption, day and night, in a typical house is 950 W. What inioi l w/0o3zd+vtial mass of $_{92}^{235}\text{U}$ would have to undergo fission to supply the electrical needs of such a house for a year? (Assume 200 MeV is released per fission, as well as 100% efficiency.)    $ \times 10^{-4}\ \text{kg}$

  What initial mass of 62j0jacgtxeh7um0s* 23ng fk $_{92}^{235}\text{U}$ is required to operate a 650-MW reactor for 1 yr? Assume 40% efficiency. The initial mass is $\approx $    $\ \text{kg}$

  Assuming a fission ofd 76k9 spy xb0oyxq3,q $_{92}^{235}\text{U}$ into two roughly equal fragments, estimate the electric potential energy just as the fragments separate from each other. Assume that the fragments are spherical (see Eq. 30-1) and compare your calculation to the nuclear fission energy released, about 200 MeV.
PE =    MeV
This is about    % larger than the nuclear fission energy released.

  What is the average kinetic energy of protons at the cebym z,d,10 s0fn9h( bzgrklk1nter of a star where the t ,k0ylzz11m sd,g fn0brb(hk9 emperature is $2 \times 10^7\ \text{K}$?
KE =    $ \times 10^{-16}\ \text{J}$
KE =    eV

  Calculate the energy rel xp; hstv2mn9pi t1;91q e+wbdeased in the fusion reaction $_{1}^{2}\text{H} + _{1}^{3}\text{H} \to _{2}^{4}\text{He} + \text{n}$ is    MeV.

  Calculate the energy req0c3v is ar 9htjg*16qleased when two deuterium nuclei fuse to form $_{2}^{3}\text{He}$ with the release of a neutron is    MeV.

  Verify the Q-value stated for each of the reactions os9a4pv;dpm .8::ktj 1k q5w gzlv )akqfEqs. 31-6.
Eqs. 31-6-a Q =    MeV
Eqs. 31-6-b Q =    MeV
Eqs. 31-6-c Q =    MeV

  Calculate the energy release per gram of fuel for the reactions lg:9 uv0 gwrn7of Eqs. 31-8a, b, and c. Compare to the7r lgwv :u09ng energy release per gram of uranium in fission.
31-8a =    $ \times 10^{23}\ \text{MeV/g}$
31-8b =    $\times 10^{23}\ \text{MeV/g}$
31-8c =    $ \times 10^{24}\ \text{MeV/g}$
Uranium fission =    $ \times 10^{23}\ \text{MeV/g}$

  How much energy is re* 5rfl f,vr3zizoq o;)leased when $_{92}^{238}\text{U}$ absorbs a slow neutron ($KE \approx 0$) and becomes $_{92}^{239}\text{U}$? Q =    MeV

  If a typical house requires 950 W of electric power on average, what g8 f1ujfw c;fk ;u0*7nbhz) m.paao;d minimum amount of deuterium fuel would have to be used in a year to supply these electrical needs? Assume the reaction of Eq.3c;u kwba d0gfo .n1h)m*7 ;ufj zfa;p81- 8b.    g

Show that the energies carr*z74bmnu;3v)tcjui -6 or pf ried off by the $_{2}^{4}\text{He}$ nucleus and the neutron for the reaction of Eq. 31-8c are about 3.5 MeV and 14 MeV, respectively. Are these fixed values, independent of the plasma temperature?

  Suppose a fusion reactor raie4. x lzn(e-wn on "d-d" reactions, Eqs. 31-8a and b. Estimate how much w-ixnee4.z(l w ater, for fuel, would be needed per hour to run a 1000-MW reactor, assuming 30% efficiency. $\approx$    $kg/h$

  How much energy (J) is contagl jvsfm)dfs/rh:8 +s 470sb2fyox :sined in 1.00 kg of water if its natural deuterium is used in sh7v/sb) ysfdfoj2rgs s4:8f m+ l:0xthe fusion reaction of Eq. 31-8a? Compare to the energy obtained from the burning of 1.0 kg of gasoline, about $5 \times 10^7\ \text{J}$.
   $ \times 10^{9}\ \text{J}$
   times more than gasoline

The energy output of massivyh gd-f- fu 8 p3ag;jx.y/nf*te stars is believed to be due to the carbon cycle (see text). (a) Show that no carbon is consumed in this cycle and that the net effect is the same as for the proton-proton cycle. (b) What is the total energy release? (c) Determine the energy output for each reaction and decay. (d) Why does the carbon cycle requ8a*ju/-f.gng htp3-xf ;yyf dire a higher temperature ($T \approx 2 \times 10^7\ \text{K}$) than the proton-proton cycle ($T \approx 1.5 \times 10^7\ \text{K}$)?

(a) Compare the energy needed for the first reaction of the carbav tr-mlocq t6z/;1vbw 9u7 f+on cycle to that for a deuterium-tritium -a+u1t 6r7cvvmb9l o twfqz;/reaction.
(b) If a deuterium–tritium reaction requires $T \approx 3 \times 10^8\ \text{K}$, estimate the temperature needed for the first carbon-cycle reaction.

  A dose of 4.0 Sv of movf*+iw: ,njnq:u- bl/;jpk gi 3+zr$\gamma$ rays in a short period would be lethal to about half the people subjected to it. How many grays is this?    $Gy$

  Fifty rads of $\alpha$-particle radiation is equivalent to how many rads of X-rays in terms of biological damage?    rad

  How many rads of slow neutrons will do as much biological damage as 759e ygabd a94ce (y:n f0o.bb*z rads of fast neutronz9bnd0*a o.gfe c(4 by9ye ab:s?    rad slow neutrons

  How much energy is deposited in the body of a 65-kg adult exposed czsixfp -;- 4ito a 2.0-Gy dose? s;p-fi iz-xc4    $J$

  A $0.025-\mu\text{Ci}$ sample of $_{15}^{32}\text{P}$ is injected into an animal for tracer studies. If a Geiger counter intercepts 25% of the emitted $\beta^-$ particles, what will be the counting rate, assumed 85% efficient?$\approx$    $ \ \text{counts/s}$

  A cancer patient is undergoing radiation therapy in which protonsowl) .) unk9bi with an energy of 1.2 n)wu)kil9b o.MeV are incident on a 0.25-kg tumor.
(a) If the patient receives an effective dose of 1.0 rem, what is the absorbed dose?
(b) How many protons are absorbed by the tumor? Assume $QF = 1$.    $ \times 10^{10}\ \text{p}$

  A 1.0-mCi source of ;wz 2tygl7a0p$_{15}^{32}\text{P}$ (in $\text{NaHPO}_4$), a $\beta^-$ emitter, is implanted in a tumor where it is to administer 36 Gy. The half-life of $_{15}^{32}\text{P}$ is 14.3 days, and 1 mCi delivers about $10\ \text{mGy/min}$. Approximately how long should the source remain implanted?    day

About 35 eV is required to produce one ion pair in air. Show dysr+ 0lg89jn that this is consistent+l j9gnyrds0 8 with the two definitions of the roentgen given in the text.

  $_{27}^{57}\text{Co}$ emits 122-keV $\gamma$ rays. If a 70-kg person swallowed $1.85\ \mu\text{Ci}$ of $_{27}^{57}\text{Co}$, what would be the dose rate (Gy/day) averaged over the whole body? Assume that 50% of the $\gamma$ energy is deposited in the body.    $\times 10^{-2}\ \text{Gy/day}$

  What is the mass of lsnvir.(-k r0 a $1.00-\mu\text{Ci}\ _{6}^{14}\text{C}$ source?    $\times 10^{-10}\ \text{kg}$

  Huge amounts of radio3ey,lgn;-tq p avaz4- 5 8cotbactive $_{53}^{131}\text{I}$ were released in the accident at Chernobyl in 1986. Chemically, iodine goes to the human thyroid. (Doctors can use it for diagnosis and treatment of thyroid problems.) In a normal thyroid, $_{53}^{131}\text{I}$ absorption can cause damage to the thyroid.
(a) Write down the reactions for the decay of $_{53}^{131}\text{I}$.
(b) Its half-life is 8.0 d; how long would it take for ingested $_{53}^{131}\text{I}$ to become 10% of the initial value? N $\approx$    $ \ \text{d}$
(c) Absorbing 1 mCi of $_{53}^{131}\text{I}$ can be harmful; what mass of iodine is this?   $ \times 10^{-12}\ \text{kg}$

  Assume a liter of milk typically has an activcapudj 6s;d (j at;3ly,:yh )jity of 2000 pCi due to $_{19}^{40}\text{K}$. If a person drinks two glasses (0.5 L) per day, estimate the total effective dose (in Sv and in rem) received in a year. As a crude model, assume the milk stays in the stomach 12 hr and is then released. Assume also that very roughly 10% of the 1.5 MeV released per decay is absorbed by the body. Compare your result to the normal allowed dose of 100 mrem per year. Make your estimate for
(a) a 50-kg adult, $\approx$    $ \times 10^{-7}\ \text{Sv/year}$ $\approx $    $ \times 10^{-5}\ \text{rem/year}$ $\approx $    $ \times 10^{-4}$ times the allowed dose
(b) a 5-kg baby.   $\times 10^{-4}\ \text{Sv}$    $\times 10^{-4}\ \text{rem}$    $ \times 10^{-4}\ \text{times the allowed dose}$

Radon gas, $_{86}^{222}\text{Rn}$, is considered a serious health hazard (see discussion in text). It decays by $\alpha$ emission.
(a) What is the daughter nucleus?
(b) Is the daughter nucleus stable or radioactive? If the latter, how does it decay, and what is its half-life?
(c) Is the daughter nucleus also a noble gas, or is it chemically reacting?
(d) Suppose 1.0 ng of $_{86}^{222}\text{Rn}$ seeps into a basement. What will be its activity? If the basement is then sealed, what will be the activity 1 month later?

  Calculate the wavelejml204 hmmm,j ngth of photons needed to produce NMR transitions in free protons in a 1.000-Thm0,mm m2jlj4 field. In what region of the spectrum does it lie? c =    $m$

  J. Chadwick discovered the neutron by bombardin h 4hjvc;v-k9jg $_{4}^{9}\text{Be}$ with the popular projectile of the day, alpha particles.
(a) If one of the reaction products was the then unknown neutron, what was the other product?
(b) What is the Q-value of this reaction?Q =    MeV

  Fusion temperatures are often given in keV. Determine the co id ;wla13mf0 fejh+2dnversion factor from kelvins to keV usin10d +efd ml 23fi;ajhwg, as is common in this field, $KE = kT$ without the factor $\frac{3}{2}$. K =    $ \times 10^{-5}\ \text{keV/K}$

  One means of enriching ura ; pvnpsx7a9nx-l2l )wnium is by diffusion of the gas $\text{UF}_6$. Calculate the ratio of the speeds of molecules of this gas containing $_{92}^{235}\text{U}$ and $_{92}^{238}\text{U}$ on which this process depends.    :1

  (a) What mass of $_{92}^{235}\text{U}$ was actually fissioned in the first atomic bomb, whose energy was the equivalent of about 20 kilotons of TNT (1 kiloton of TNT releases $5 \times 10^{12}\ \text{J}$)? $\approx $    $\ \text{kg}$
(b) What was the actual mass transformed to energy?$\approx $    $\ \text{g}$

  In a certain town the average yearly background radiate51qni qhazcg, ed4oh9p8 /t0ion consists of 21 mrad of h9pq oge 0h/in 1ztca5e4d,q8 X-rays and $\gamma$ rays plus 3.0 mrad of particles having a QF of 10. How many rem will a person receive per year on the average?dose(rem) =   $ \times 10^{-2}\ \text{rem/yr}$

  Deuterium makes up 0.0115% of natural hydrogen on average. Make a royzxw -ikpa 4,vjb6q,a ,4v/ptugh estimate of the total deuterium in the Earth's oceans and estimate the tot,vki6/w,b 4pja v,4pytqa - zxal energy released if all of it were used in fusion reactors.

The total mass of deuterium is about    $ \times 10^{16}\ \text{kg}$
The total energy is about    $\times 10^{30}\ \text{J}$

  A shielded $\gamma$-ray source yields a dose rate of $0.052\ \text{rad/h}$ at a distance of 1.0 m for an average-sized person. If workers are allowed a maximum dose of 5.0 rem in 1 year, how close to the source may they operate, assuming a 40-h work week? Assume that the intensity of radiation falls off as the square of the distance. (It actually falls off more rapidly than $\frac{1}{r^2}$ because of absorption in the air, so your answer will give a better-than-permissible value.)    m

Radon gas, $_{86}^{222}\text{Rn}$, is formed by $\alpha$ decay. (a) Write the decay equation. (b) Ignoring the kinetic energy of the daughter nucleus (it's so massive), estimate the kinetic energy of the $\alpha$ particle produced. (c) Estimate the momentum of the alpha and of the daughter nucleus. (d) Estimate the kinetic energy of the daughter, and show that your approximation in (b) was valid.

  Consider a system of nuclear power plants that pr;.,9 eyllqd.l0usj n nf3 d(fmoduce 3400 MW.
(a) What total mass of $_{92}^{235}\text{U}$ fuel would be required to operate these plants for 1 yr, assuming that 200 MeV is released per fission? $\approx$    $ \ \text{kg}$
(b) Typically 6% of the $_{92}^{235}\text{U}$ nuclei that fission produce $_{38}^{90}\text{Sr}$, a $\beta^-$ emitter with a half-life of 29 yr. What is the total radioactivity of the $_{38}^{90}\text{Sr}$ in curies, produced in 1 yr? (Neglect the fact that some of it decays during the 1-yr period.) $\dfrac{\Delta N}{\Delta t}$    $ \times 10^{6}\ \text{Ci}$

  In the net reaction,, for thqxl5 q:jv93)r0psp f ce proton-proton cycle in the Sun, the neutrinos escape from the Sun with energy of about 0.5 MeV. The remaining energy, 26.2 MeV, is available within the Sun. Use this value to calculate the "heat of combustion" per kilogram 5)rspvpj9xf q03cq l:of hydrogen fuel and compare it to the heat of combustion of coal, about $3 \times 10^7\ \text{J/kg}$.    $ \times 10^{-14}\ \text{J/g}$
This is about    $ \times 10^7$times the heat of combustion of coal.

  Energy reaches Earth from the Sun at a rate+p/j4+tss+x ev 1t gvp of about $1400\ \text{W/m}^2$. Calculate
(a) the total power output of the Sun,$\approx $    $ \times 10^{26}\ \text{W}$
(b) the number of protons consumed per second in the reaction of Eq.31- 7, assuming that this is the source of all the Sun's energy. $\approx $    $ \times 10^8\ \text{protons/s}$
(c) Assuming that the Sun's mass of $2 \times 10^{30}\ \text{kg}$ was originally all protons and that all could be involved in nuclear reactions in the Sun's core, how long would you expect the Sun to "glow" at its present rate? See previous Problem.$ \approx $    $ \times 10^{11}\ \text{yr}$

  Some stars, in a later stage of evolution, mtuhlcg3f+* nnw /r)6wp)2a5 8hng pumay begin to fuse two $_{6}^{12}\text{C}$ nuclei into one $_{12}^{24}\text{Mg}$ nucleus.
(a) How much energy would be released in such a reaction?
(b) What kinetic energy must two carbon nuclei each have when far apart, if they can then approach each other to within 6.0 fm, center-to-center? KE =    $ \times 10^{-13}$ =    MeV
(c) Approximately what temperature would this require?   $ \times 10^{10}\ \text{K}$

  An average adult body contains 4j *5wkk5m o m1ytx.lhabout $0.10\ \mu\text{Ci}$ of $_{19}^{40}\text{K}$, which comes from food.
(a) How many decays occur per second?    $\ \text{decays/s}$
(b) The potassium decays produce beta particles with energies of around 1.4 MeV. Calculate the dose per year in sieverts for a 50-kg adult.    $\times 10^{-4}\ \text{Sv/y}$
Is this a significant fraction of the $3.6\ \text{mSv/year}$ background rate?    %

  When the nuclear reactor accident occu/txmhuge v6e0wt+n70 rred at Chernobyl in 1986, $2.0 \times 10^7\ \text{Ci}$ were released into the atmosphere. Assuming that this radiation was distributed uniformly over the surface of the Earth, what was the activity per square meter? (The actual activity was not uniform; even within Europe wet areas received more radioactivity from rainfall). $\frac{\text{Activity}}{\text{m}^2}$=   $ \times 10^{3}\ \text{decays/s}$

  A star with a large helium rf5+ez:z jme9abundance can burn helium in the reaction $3\ _{2}^{4}\text{He} \to _{6}^{12}\text{C} + \gamma$. What is the Q-value for this reaction? Q =    MeV

  A $1.0-\mu\text{Ci}\ _{55}^{137}\text{Cs}$ source is used for 2.0 hours by a 75-kg student in a physics lab. Radioactive $_{55}^{137}\text{Cs}$ decays by $\beta^-$ decay with a half-life of 30 years. The average energy of the emitted betas is about 190 keV per decay. The $\beta^-$ decay is quickly followed by a $\gamma$ ray with an energy of 660 keV. Assuming the student absorbs all emitted energy, what effective dose (in rem) is received during lab? dose $\approx $    $ \times 10^{-5}\ \text{rem}$

  A large amount of $_{38}^{90}\text{Sr}$ was released during the Chernobyl nuclear reactor accident in 1986. The $_{38}^{90}\text{Sr}$ enters the body through the food chain. How long will it take for 90% of the $_{38}^{90}\text{Sr}$ released during the accident to decay? See Appendix B.$\approx $    y

Three radioactive sources have the same activity, r51rj u: zs8hmd* 5c9r fmv0lc25 mCi. Source A emits 1.0-MeV 9 vmz*0dr1jlsc85m: cfr 5 rhu$\gamma$ rays, source B emits 2.0-MeV $\gamma$ rays, and source C emits 2.0-MeV alphas. What is the relative danger of these sources?

  A 70-kg patient is to be given a medical test involving the ing 3ob7bfb (shz.estion of $_{43}^{99\text{m}}\text{Tc}$ (Section 31-7) which decays by emitting a 140-keV gamma. The half-life for this decay is 6 hours. Assuming that about half the gamma photons exit the body without interacting with anything, what must be the initial activity of the Tc sample if the whole-body dose cannot exceed 50 mrem? Make the rough approximation that biological elimination of Tc can be ignored. Activity $\simeq $    $\ \text{mCi}$