Fill in the missing particles or nuclei: ,a52 0kmo kymzaww3r0
(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 projectiles for producin apdhev 14m8p..t me5tg 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 fragments1 wtq 8 e(5 ; qqpkuw5a8)swrvgfm6i)q $\beta^+$ 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 fisrq +7bxgtixgd5 g;l )*sion appears in the form of thermal energy - but the thermal enedq)+rl 7b* x;5ggxgtirgy of what?

The energy from nuclear fission appears in the form of thermalmm 6*prle /46+jrpr/4bas* lohb+yh q energy - but the thermala4jy6p/ rlle h psbr/6* omh +*mq4br+ energy of what?

Why can't uranium be enriched by chemical means?z su1dc*9ppa.kz5bt 0

How can a neutron, with practically no kinetic energy, excite a nucl;w 9gjek 5lgwe0etm;2eus to the extent swggje9m l;ktwe5 20 e;hown in (Fig. Below)?

Why would a porous block of uranium be more likelw+ogx5.bg5nj/8ojf t vw a +r0y to explode if kept under water rather than in air?baf5wj v/r5og gn+w+o .tj80x

A reactor that uses highly i5etn.2gsr(lo4h -y nbkfp+1 enriched uranium can use ordinary water (instead of heavy water) i-5p4gsthy(r l2bf k1n.e n+o as a moderator and still have a self-sustaining chain reaction. Explain.

Why must the fissionwdswq :-9 o,j aw1aft2 process release neutrons if it is to be useful?

Discuss the relative vb+9 wuw k,ry 5x+2gnomerits and disadvantages, including pollution and safety, of power generat5y n xoww+uk2gbv+r 9,ion by fossil fuels, nuclear fission, and nuclear fusion.

What is the reason for the "secondary system" in (gloj amxy :t;xdv2l4pa; x;/a nuclear reactor, (Fig. Below)? That is, why i jxp xltg;;da v/;x:(4yoal m2s the water heated by the fuel in a nuclear reactor not used directly to drive the turbines?

Why are neutrons released in a fig;s: s g d36zvyffkzi (q5+4afssion reaction?

Why do gamma particles pub5qusc v( 14 3jtkvadlb7 c*8enetrate matter more easily than beta particles do?

A higher temperature is required for deuterium-deuterium ignition than fb:f jwj.1j,n2sq xv 1gor deuterium-trgv2,1 j:xfnwb q1s jj.itium. Explain.

Light energy emitted by the he,rg8;nqambo+ bd1 / Sun and stars comes from the fusion process. What conditions in the interior of stars mm+a1 / b;gorebq,nd 8hake this possible?

How do stars, and our Suns8tc./ lb p*:mz:qmjj, maintain confinement of the plasma for fusion?

What is the basic differedo9m(u .hhb/v nce between fission and fusion?

People who work around metals that emit alpha2mi if :vk9of. particles are trained that there 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 eat2ffi: oimk.9 ving and drinking while working, and against machining the metal. Why?

Why is the recommended maximum radiation dose hgk-j. u,cup s hm2m0d8d2l .uligher for women beyond the child-bearing age than for ycuhm2s.8.u0ml d-pd, lkgj2 uounger women?

Radiation is sometimes used tgyoks4hy,ysvt u9)bai. 0k,1 o sterilize medical supplies and even food. Explain how uvkot,)b k .sya9s, 1y0y4higit works.

What is the difference between absorbed dose and etnnobwu) (.2qbu;jeom* 8t 3gffective dose? What are the SI units for jqm;e)*og8o3( wn n .2bu utbteach?

How might radioactive tracers be used to find a leak in a pipe?-njs+yhgkun0 c4:ba 2

Natural aluminum is 8n k v5odjnp-f0)mu bk2f9zy/ all $_{13}^{27}\text{Al}$. 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 ry 9-h(nrom (sfeaction $_{1}^{2}\text{H} + _{1}^{2}\text{H} \to _{2}^{3}\text{He} + \text{n}$ 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 released (or energy input required) for the reacti nfs:g- tndox8hb5 nu27jw.j6on $_{5}^{10}\text{B} + \text{p} \to _{3}^{7}\text{Li} + \alpha$.    MeV

  (a) Can the reactionx +kqq.e 34n2 r4mgzcy $_{11}^{23}\text{Na} + \text{d} \to \text{n} + _{12}^{24}\text{Mg}$ 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 +-v 3knmdht 8p$_{3}^{7}\text{Li} + \text{p} \to _{2}^{4}\text{He} + \alpha$ 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 the "wa6 g .giag8yugp5q3 5capture" 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 products of the rea i*o1gyno.ffd ; (f1rbction $_{6}^{12}\text{C} + \text{d} \to _{7}^{13}\text{N} + \text{p}$ 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 "strip e8*phhax7+qn ping" 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" nuclear rebjxg,a37rlqzl2n42/f apo /eaction 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 rea:ycg8 yhw fh/056b ewaction: $\text{p} + ? \to _{16}^{32}\text{S} + \gamma$.
(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 tty0 60aib5,ze pim/xthe fission reaction $_{92}^{235}\text{U} + \text{n} \to _{56}^{141}\text{Ba} + _{36}^{92}\text{Kr} + 3\text{n}$. 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 j73* - zw np -w8gk7pl9 yg.xvwx5loqzznklqwz w7 7-xopgx-pjv*9 5 y.8gl3w$_{56}^{140}\text{Ba}$ and $_{36}^{92}\text{Kr}$ are 140.914411 u and 91.926156 u, respectively.) Q =    MeV

  How many fissions take place per second in a 200-MW reactornt9y qc(li jp (xj12,i? Assume 200 MeV is released per fissioijxiq((2p c l n1j,ty9n. P =    $\times 10^{13}\ \text{reactions/s}$

  The energy produced by a fission reactor zae t,r5y09gaqh7s (gr1ka 9his about 200 MeV per fission. What fraction of the rest mass of a 97 (g1g9asy 0r5,aazk rqehht$_{92}^{235}\text{U}$ nucleus is this?$\approx1/$   

  Consider the fission reactionyyvpb ht,irb)4w;4i : $_{92}^{235}\text{U} + \text{n} \to _{51}^{133}\text{Sb} + _{41}^{98}\text{Nb} + ?\text{n}$.
(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 power1)b0 6mv:u ba gd6jvrv consumption, day and night, in a typical house is 950 W. What inivv1j )du66:0rbvmb ga tial 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 l qi5wk(st2tv chf: 6-1*pmze$_{92}^{235}\text{U}$ is required to operate a 650-MW reactor for 1 yr? Assume 40% efficiency.$\approx $    $\ \text{kg U}$

  Assuming a fission of 3 v(*9.iw2ye.s k5cxjigbod 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 center of a skp059 i9xcx k(8tnlg ftar where the temperature ispl9(509xg8i ktxkf n c $2 \times 10^7\ \text{K}$?
KE =    $ \times 10^{-16}\ \text{J}$
KE =    eV

Show that the energy released in the fusion reaction aex ; *1 h/t0c8q:; yraeo12fizvq hsv$_{1}^{2}\text{H} + _{1}^{3}\text{H} \to _{2}^{4}\text{He} + \text{n}$ is 17.59 MeV.

Show that the energy released 5pb 5poc*qq 4g:svq7p *vn:urr*(namwhen two deuterium nuclei fuse to form $_{2}^{3}\text{He}$ with the release of a neutron is 3.27 MeV.

  Verify the Q-value stated for each of the reactions ofEqs. 6. [Hint: Be careful with electrons.]

6-b Q =    MeV
6-C Q =    MeV

  Calculate the energy release per gram /zqv d-k cc0hrn7, zl:of fuel for the reactions of Eqs. 8a, b, and c. Compare to the energy re/lcnr7vkz hcz-d0:q ,lease per gram of uranium in fission.
8a =    $ \times 10^{23}\ \text{MeV/g}$
8b =    $\times 10^{23}\ \text{MeV/g}$
8c =    $ \times 10^{24}\ \text{MeV/g}$
Uranium fission =    $ \times 10^{23}\ \text{MeV/g}$

  How much energy is released wh5fqhfcs ntm.,l-.j: m en $_{92}^{238}\text{U}$ absorbs a slow neutron ($KE \approx 0$) and becomes $_{92}^{239}\text{U}$? Q =    MeV

  If a typical house requires 950 W of d6sg,eue1 u0h electric power on average, what minimum amoseedh ug,u106unt of deuterium fuel would have to be used in a year to supply these electrical needs? Assume the reaction of Eq. 8b.    g

Show that the energies carried94*fk sj4y; eh.jmf dw off by the $_{2}^{4}\text{He}$ nucleus and the neutron for the reaction of Eq. 8c are about 3.5 MeV and 14 MeV, respectively. Are these fixed values, independent of the plasma temperature?

  Suppose a fusion reactor ran on "d-d" io ,8tufsm vapn+x06,2wz/yb-o, zwpreactions, Eqs. 8a and b. Estimate how much water, for fuel, would bw, ab6+twmyo2, ps-f/v z xpuz08o i,ne needed per hour to run a 1000-MW reactor, assuming 30% efficiency. $\approx$    $kg/h$

  How much energy (J) is contained in 1.00 kg of wgzfvi0 u52we8d6i -xpater if its natural deuterium is used in the fusion reaction of Eq. 31-8a? Compare to the energy obtained from the burning of 1.0 kg of gaiuzv gfxi65d0e-2pw8 soline, about $5 \times 10^7\ \text{J}$.
   $ \times 10^{9}\ \text{J}$
   times more than gasoline

The energy output of massive stars is believed to be d3lma8yq8hl (7yx l09spf mp .7f hcfz*ue 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 require a higher temperat 39zsm8phy7*(.mpxhcff0q7 l 8l flyaure ($T \approx 2 \times 10^7\ \text{K}$) than the proton-proton cycle ($T \approx 1.5 \times 10^7\ \text{K}$)?

(a) Compare the energy needed for the first ;0lu8 kpwqu 6sz46oazreaction of the carbon cycle to that for a deuterium-tr4 8suk6 6w0oaqzl;zpuitium 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 f zwgr p:q+.,vc/zszwc .nm01$\gamma$ 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 neurwge*d. c,7-nm)rbp strons will do as much biological damage as 75 rads of fast neutrons?7.d gcs-p,w)m* ernr b    rad slow neutrons

  How much energy is dee15uq7 qza2 9jhu3vtzw3/hsc posited in the body of a 65-kg adult exposed to a 2.0-Gy dos9 jv 2zc1e3s u3wq5ahz7hu/ tqe?    $J$

  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 therapaeg , x8f bogbh92nkw4(ceg 23y in which protons with an energy of 1.2 MeV are incident on a 08(e2b3 2wk4n, gx9o g gacebfh.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 k.-ov 0gcjmmm8j (gf5tsu; (l $_{15}^{32}\text{P}$ (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 pacr6vi8 )b/mvw1 ah 6klir in air. Show that this is consisteibrlh 16wv/ak)c 86 mvnt 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 a xk:mq xcy*ytzg u* 529$1.00-\mu\text{Ci}\ _{6}^{14}\text{C}$ source?    $\times 10^{-10}\ \text{kg}$

  Huge amounts of radioactive xcb2o dc 8*3z,-x gxzr$_{53}^{131}\text{I}$ 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 activity of 206c/ zbjn2snu 500 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 wavelength of photons needed to produce NMR transitions in fc5+yl tjjk2*8 -e+x ilgi(m5 pk*cz(6 svjydhree proydl jcvxz +(cs*k +-kyjlh5 pit2j*e8m( 5i6g tons in a 1.000-T field. In what region of the spectrum does it lie? c =    $m$

  J. Chadwick discovered the u +la/ y1(bwvoneutron by bombarding $_{4}^{9}\text{Be}$ 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 couv),zn7 q. d+gnumyjvqy2nmlk( 1*. x7 :pgisnversion factor from kelvins to keV using, as is commo2 j7miu z:n7yl*xsy (m,1. q.n ng)+g qkpvuvdn in this field, $KE = kT$ without the factor $\frac{3}{2}$. K =    $ \times 10^{-5}\ \text{keV/K}$

  One means of enriching uranium is by diffu9fvgw exi dc;2st3n+zp d 2m01sion 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 radiation consis +wxm4n*chf3knk*q 1pts of 21 mrad of X-rays and *m43nw+ nkx* hcp1kf q$\gamma$ 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 rough estima.24b ;ruld wgste of the total deuterium in the Earth's oceans and estimate the total energy released if all of it were use u.r;2b wgsd4ld in fusion reactors.
$\approx $    $ \times 10^{15}\ \text{d atoms}$
$\approx$    $ \times 10^{16}\ \text{kg d}$
   $\times 10^{30}\ \text{J}$

  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 o(xt kk8 +aoo*power plants that produce 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 the proton)xn4 aee.s b+lw2cjlhq- s /9g-proton cycle in the Sun, the neutrinos escape from the Sun with energy of about 0. 2x4qec-)wl./sa jbhsnge+l9 5 MeV. The remaining energy, 26.2 MeV, is available within the Sun. Use this value to calculate the "heat of combustion" per kilogram 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 am n*; ;fvhtqum p/4ct1qu9b9it a rate 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. 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 e(+ ru*k( jxkbf*;) f fzh3t6xnsb v.egvolution, may 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 containb qy;jtd; ctg,*y ip 3-oy4fq;s about $0.10\ \mu\text{Ci}$ 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 occurred at Chernobyl in 19-k r 6w0e6ot2p(in haex: gyi6 ms;e+n86, $2.0 \times 10^7\ \text{Ci}$ 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 aw/c rqlpx2rga(7u g w35(/cjj bundance 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 activityoc )f*kqt9g z8f ,hr8v, 25 mCi. Source A emits 1.0-MeV foctk,qr8zg 8*9fv)h $\gamma$ 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 med7kjueue)l. /gk +3p r;k ro(roical test involving the ingestion 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 $    $\ \text{mCi}$