Fill in the missing particles or nuclei: 3ph5me5 zy:s y jlga;6ue )h)+:qapw n
(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 sucg mz/lfp) 9g*r ch.r;w4avesh.sd1r, h good projectiles 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 fragmentxm0zs ./ a,;e() loac2lwslsts $\beta^+$ 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 t3rs) kpyv 3;nehe thermal energy ofe; 3knpr)syv 3 what?

The energy from nuclear fission appears in the form of thermal ene-il5to h.(f; js 6jrtprgy - but the thermal energy of whs;t.6hf p jtj5o-(rl iat?

Why can't uranium be enriched by chemical means f9 8mdo5evy.ih+ibh) wszp5.?

How can a neutron, with practically no kinetic energy, excite a nucleus to the gvep0fge- 65+r 3kk dnextent kvgd+n3 5e-0fk6rpgeshown in (Fig. Below)?

Why would a porous block of uranium be more likely to explodn; )feo, j)jywe if kept under water ej;w), onyj)f rather than in air?

A reactor that uses highly enriched uranium can use ordinary water (fh7odz .,:gk kinstead of heavy water) as a moderator and still have a kdg: kh.z7fo,self-sustaining chain reaction. Explain.

Why must the fission process release neutrons if it is2/+mx(bbxp - kjs,zxa)vwx* nh 6fl) t to be useful?

Discuss the relative merits and disadvantages, including pollution and sa gqrm5i6b19i dfms))6 bxzj; ofety, of power generation by fossil fuels, nuclerb66)zdqm gj 91 is);mixfob5ar fission, and nuclear fusion.

What is the reason for the "secondary system" in a nuclear reactor, (Fig. Beloj 8q yu8,ea 181 ;r::i(cxtbfytqzzziw)? That is, why is the water heated by thqz u11yz,c:etb axj8 z( i88fitry:q ;e fuel in a nuclear reactor not used directly to drive the turbines?

Why are neutrons released in a fission , pzuv5 r k8nm/+kh9ocreaction?

Why do gamma particles pen8:aj8;vf0uy ush,m cp etrate matter more easily than beta particles do?

A higher temperature is required for deuterium-deuterium ignition thai54df6 im3wo zn for deuterium-tritium.o35miifzd46 w Explain.

Light energy emitted by the Sunblgxaeikl( ,eb: r71 5 and stars comes from the fusion process. What conditions in the interior of stail17:kg ex5bab(rle ,rs make this possible?

How do stars, and our Su(i4j*y -et-*aw l gprcn, maintain confinement of the plasma for fusion?

What is the basic difference between fissijw6bs0xb he)j)2nqw1,ptx 6 eon and fusion?

People who work around metals that emit alpha particles are trained that;o d)kpnopnujxc6 mep7mv4 0e ):61sw 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 eating and drinking while working, an) 10;xu ecdn6v:4k pj mon)ms pep6o7wd against machining the metal. Why?

Why is the recommended maxi *uy 58cu ,fs2(iss6ya(.felckl r) +uxd-xxomum radiation dose higher for women beyond the child-bearing age than for young(l.x5 ycsf -y+(osx,u *aui) r6ceusk x fd82ler women?

Radiation is sometimes2 e:-b,yax+jvii69 mwl aa hw+ used to sterilize medical supplies and even food. Explain ibe,wx i9hm ++v2wla-6a:a yj how it works.

What is the difference between absorbedn1gyai x0pd/0 ;duea9)v+yrj:ufi3y dose and effective dose? What are the SI units for nujp1) i0yd yv;:faa9gr ye+id x/03u each?

How might radioactive tracers be used to find a leak i ldk7;3zusd-nlzq 0/xmp,7n f n a pipe?

Natural aluminum is auz1:zn 7 6qccyll $_{13}^{27}\text{Al}$. 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 reactiouxoa zg -,2)ean $_{1}^{2}\text{H} + _{1}^{2}\text{H} \to _{2}^{3}\text{He} + \text{n}$ 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 releasy d 7t;8ke 8ppzw)(xazed (or energy input required) for the reaction $_{5}^{10}\text{B} + \text{p} \to _{3}^{7}\text{Li} + \alpha$.    MeV

  (a) Can the reaction7 a g5e.1 n7) ccqxpluqg91hun $_{11}^{23}\text{Na} + \text{d} \to \text{n} + _{12}^{24}\text{Mg}$ 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 +4z.t.nn w 19rfpzt mu$_{3}^{7}\text{Li} + \text{p} \to _{2}^{4}\text{He} + \alpha$ 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 "capture"ot4rj di) w55i reaction $_{2}^{4}\text{He} + _{4}^{9}\text{Be} \to _{6}^{12}\text{C} + \text{n}$. Q =    MeV

  Calculate the total kinetic energy of ther fj.r d;c.r*6pa ycj) products 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 "stripping"0.xt ;jtukroq2z )fi9 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 reactir51a gvy)dxpb-4l fw6on 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 8 j i*+l2hro6mh3(ai jbu8lde nuclear reaction: $\text{p} + ? \to _{16}^{32}\text{S} + \gamma$.
(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 fisvek4c+ h8xt f 8ze;kc +3fa+sqsion 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.2t d.jp zyzu9+ 31-4? (The masses of u+9jpz 2ty.dz$_{56}^{140}\text{Ba}$ 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 /kmj4f f(i bktwl),9s reactor? Assume 200 MeV is released per f ikl9(jkfsb,4m)t wf /ission. P =    $\times 10^{13}\ \text{reactions/s}$

  The energy produced by a fission reactor is about 200 MeV per fission. Wha9.w6 a*n x9,z mzaesqjt fraction of the rest maaqa,j6m9 ze9wnxsz*. ss of a $_{92}^{235}\text{U}$ nucleus is this? The ratio is about $\approx 1 : $   

  Consider the fission reacti zv1lo x4d5cfq 6zbe3.on $_{92}^{235}\text{U} + \text{n} \to _{51}^{133}\text{Sb} + _{41}^{98}\text{Nb} + ?\text{n}$.
(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 power consumption, day and night, in a tt tvf9 qeqrr8i/:sp5xzi (30 cypical house is5rqir8fctq0 v9sx i(/ezp: 3t 950 W. What initial 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 ofjkss et rp*b;63 h9s6n $_{92}^{235}\text{U}$ is required to operate a 650-MW reactor for 1 yr? Assume 40% efficiency. The initial mass is $\approx $    $\ \text{kg}$

  Assuming a fission o5b gts(vvfg7-ki4yiyd264 pf f $_{92}^{235}\text{U}$ 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 kine:hh r3gnu32ii8)f t ltjnv(x- ;z3dcc tic energy of protons at the center of a star where the temp38lht(g :dfh 3cvj)2u;icn-n3 i rtxzerature is $2 \times 10^7\ \text{K}$?
KE =    $ \times 10^{-16}\ \text{J}$
KE =    eV

  Calculate the energy released in then)72qhcrcu mqh83 u d4 fusion reaction $_{1}^{2}\text{H} + _{1}^{3}\text{H} \to _{2}^{4}\text{He} + \text{n}$ is    MeV.

  Calculate the energy released when two deute p) i w-fjigpwgvzf0vy6)* 49yrium 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 ofErwgld4u, p 4z+qs. 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 of Eqs. 31-8 sntb- p,xzhif p;qd6ckg,x(04+. euta, b, and +x,n u4cttpgxpf ;dkzb0(- .6qi,eshc. Compare to the 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 release0mcxi c8- sm0zwf7 4byn6nhw )xk2 r1pd 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 p9d v..y1lp jj voyk/*:ub,durower on average, what minimum amount of deuterium fuel would have to be used in a year to supply these electrical needs? Assume the reactio vpu.kv dj/oly1* .,j9udy:brn of Eq.31- 8b.    g

Show that the energies carried o.mkrypua t95) ff 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 ran on "d-d" reactions, Eqs. 31-8a6uwbx*z ;nnyojhk/* /eo s y/- and b. Estimate how much water, for fuel, would be needed per hour to run a 1000-MW reactor, assuminobn *-/jz k6 yno/yw/e ;*suhxg 30% efficiency. $\approx$    $kg/h$

  How much energy (J) is contained in 1.00 kg of water if its natural deuteriuiobep;i (7 9hem is used in the fusion reaction of Eq. 31-8a? Compare to the energy obtained from the bue (h;bep9i7io rning 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 massive stars wxfgg8a9 ,) w-j:o tqzis 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 forqgt8f)-azj wx9wo:, g 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 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 c f ljygn jmw8n,hop781bf2 9r)x5t m-for the first reaction of the carbon cycle to that for a deuterium-tritium reacti 2yp8m f8njhtgnof cl51) x97rb-,mjwon.
(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 vg 8h/4tz3iuc$\gamma$ 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 e mm:3w*twuo. m- tmbe+--o el0g jpyy3jn ,r2much biological damage as 75 rads of fast neutro re g -jmeoymewmy-uj*t,0+bmt3 . 2:w3lon-pns?    rad slow neutrons

  How much energy is de1byzu*cm 47 srposited in the body of a 65-kg adult exposed to a 2.0-Gy dose4y1brzs7 m* cu?    $J$

  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 proton o9v) )nfduw;hs with an energy of 1.2 MeV are incident on 9)vwno)hud; fa 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 lgv3a,x9 v0w doti:+ q$_{15}^{32}\text{P}$ (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 that this is co-v/;-)r4gopd j gnm m zfyg:5onsistent with the two definitions ognym o/rvg:d z-g-)5f;jpm o4f 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-r3xvs fn g/ ah j8 /m3fi1rql5a)8byy $1.00-\mu\text{Ci}\ _{6}^{14}\text{C}$ source?    $\times 10^{-10}\ \text{kg}$

  Huge amounts of radioacuxex7/ oh ftt*/u,o-rr h+eu8 tive $_{53}^{131}\text{I}$ 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 ew)a9oj1 cw:wckj ,s(activity 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 wavelength of photoa-b5s zkc *4mhns needed to produce NMR transitions in free protons in a 1.000-T field. In h-cs ab*45kzm what region of the spectrum does it lie? c =    $m$

  J. Chadwick discovered the ng(x y yb2lsi/3eutron 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. Determin9( 1 w,xmxrq*1rg*qs)7w(jsjkoac tle the conversion factor from kelvins to keV using, as ism*rx7wqt1o ) (l qawr*g,s j1sj(c k9x common 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 diffusagxu3 64ehbvzk4hflp57 ,: dzion 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 backgrou98ap dze+tnt; oxb-sr2q m8. rnd radiation consists of 21 mrad of X-razsxd+ t.ar9 82mbn e;qrop t-8ys 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 natued/5,ow1gmus ral hydrogen on average. Make a rough estimate of the total deuterium in / edu51,msgwothe Earth's oceans and estimate the total 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 produ; .iqv f9wp1z/k3d sm3bb fvn)2lmomg( o m.g4ce 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-proton cycle in the Sun, the neutrinos epqg 2(r6lc 8m)ng7cnvscape from the Sun with energy of about 0.5 MeV. The remaining energy, 26.2 MeV, is available within the Sun. Use this va(mc ncn68r qlgg7p 2v)lue 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+e6d4 i:g)s+pp*j, x h wii:v.cxrfww at 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.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 evol5qap : 2hz4u7 qg+dpzeution, 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 body5w2q vla;dce0 contains 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 ia 6-fnh7ol;xqbnfe +3 l2 dw-dn 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 abundance cck hu/uwt 1 wx.1x1gw-an 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, 25 mCi. Source A emits 1.0-MeVoztj:0 .p0-wdh43 (p fyzm vue e: v.dfpz 0p zw(jth3m-u 0y4o$\gamma$ 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 ingestion o2.z -ng/qxn fxf $_{43}^{99\text{m}}\text{Tc}$ (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 $    $\ \text{mCi}$