Physics Unit33: Astrophysics and Cosmology

1#

The appearance of the great range of brighnamjq2a8)1qv bf ja 9oa+n/ .wy2f uz;tness among stars is due to (1.0 分)

A. the differences in the amount of light different stars emit.

B. the differences in the distances of stars from us.

C. both of the given answers

D. none of the given answers

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2#

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The absolute luminosi fu*p,1.n1,wdxdit qhw :s2 e6imq6 brty for most stars depends on the (1.0 分)

A. radius of the star.

B. cross sectional area covered by the star.

C. volume covered by the star.

D. the mass of the star.

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3#

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Four different main-sequeg+f8hlj y49g9ax 9jvk nce stars are colored blue, orange, red, and yellow. Whatjy49k vj8fgah+99lx g is their rank from coolest to hottest? (1.0 分)

A. blue, yellow, orange, red

B. orange, blue, yellow, red

C. red, orange, yellow, blue

D. red, yellow, orange, blue

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4#

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A Hertzsprung-Russell diagra qy0ej*4fiizv-6hck (m shows stars on a plot of (1.0 分)

A. apparent brightness vs. temperature.

B. luminosity vs. temperature.

C. luminosity vs. distance.

D. magnitude vs. apparent brightness.

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5#

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A white dwarf star with a mass 7)z;fj;d6r j yuytq/zequal to that of the Sun is about the size of (1.0 分)

A. the Sun.

B. the Earth.

C. a basketball.

D. a baseball.

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6#

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The Chandrasekhar limit of stellar mass (below which a star will collapse in;(lzq tjsa(+ gto a white dwarf) is, if the mass of our S qgjt((+sl;az un is M, about (1.0 分)

A. 0.8 M.

B. 1.2 M.

C. 1.4 M.

D. 1.9 M.

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7#

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Supernovas are thought to always result i;j(qn5yp negc9gmo3+5km -(d e w +ckun (1.0 分)

A. neutron stars.

B. red giant stars.

C. regular stars like our Sun.

D. white dwarfs.

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8#

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Black holes (1.0 分)

A. are holes in space, devoid of matter.

B. are predicted by Einstein's special theory of relativity.

C. are the collapsed remnant of stars.

D. cannot be detected in binary star systems.

E. are a violation of Einstein's general theory of relativity.

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9#

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Pulsars are rapidly spinniner;5i t54tb;d 4ltkbcs m-tq *g (1.0 分)

A. regular stars like our Sun.

B. red giant stars.

C. neutron stars.

D. white dwarfs.

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10#

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State Einstein's principle of equivalence.ps;2,fj4y ayk (1.0 分)

该题自我估分: (必填) (满分:1.0分)

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11#

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The Schwarzschild radius of a black hole is that rad:flcd::clbeemu6m m)u91on 5ial distance from the center of a sphere within which not even light can escape. It was first discovered mathematically by Schwarzschild in 1916 after Einstein published his general relativitelfmmcd cmu15:e : u9:no)lb 6y theory. It can be calculated from a star's mass M as: $R = 2GM/c^2$. Take the radius of both stars A and B as the Schwarzschild radius. If the mass of star A is twice as much as the mass of star B, the average density of star A, compared to star B will be (1.0 分)

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12#

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When a distant source emits light of a particular wavelength5:bu vta.netqkgzq2n y ar/si31 0;/ y in the visible, and the source is moving away from us, the n r5/yk3y2/eb :a 0sn1a ttqqi v.gu;zcolor of the light appears to us to be shifted toward the (1.0 分)

A. red end of the visible spectrum.

B. blue end of the visible spectrum.

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13#

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The cosmic background radiation corresponds to a temper )ongw qs/zrj6 p:;qn,ature of about (1.0 分)

A. 1.4 K.

B. 2.7 K.

C. 3.0 K.

D. 3.3 K.

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14#

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The Sun has apparent brightness /mh u9r5vuew4zam 18w at Earth ($1.5 \times 10^{8} \; km$ away) of B. What would be the apparent brightness of the Sun at Pluto, which is $6.0 \times 10^{9} \; km$ from the Sun? (1.0 分)

A. $0.25 \; B$

B. $0.063 \; B$

C. $0.025 \; B$

D. $0.00063 \; B$

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15#

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A star has absolute luminosity equal to that of the .*n o8 1zdtqpsSun ($1.5 \times 10^{8} \; km$ from the Earth) but is 10 pc away from the Earth. By what factor will it appear dimmer than the Sun? (1.0 分)

A. $2 \times 10^{-9}$

B. $2 \times 10^{-11}$

C. $2 \times 10^{-13}$

D. $2 \times 10^{-15}$

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16#

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The Earth's orbit has a meaiy.v,oapx((afx9 cdh b h0p+:n radius of $1.5 \times 10^{8} \; km$. Over a six-month period, the apparent position of a particular star varies by $0.00014^{\circ}$ due to parallax. How distant is the star, in km? (1.0 分)

A. $1.2 \times 10^{11} \; km$

B. $1.2 \times 10^{14} \; km$

C. $1.2 \times 10^{17} \; km$

D. $1.2 \times 10^{20} \; km$

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17#

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The Earth's orbit has a mean rth+4ld ;-ch weadius of $1.5 \times 10^{8} \; km$. Over a six-month period, the apparent position of a particular star varies by $0.00014^{\circ}$ due to parallax. How distant is the star, in ly? (1 ly = $9.46 \times 10^{15} \; m$) (1.0 分)

A. $0.13 \; ly$

B. $1.3 \; ly$

C. $13 \; ly$

D. $130 \; ly$

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18#

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What is the parallax angle for Proxima Centauri, which is Earv4 /py+g ps7vath's nearest star aty7v gpps/4+a v 4.3 ly? (1.0 分)

A. $1.2 \times 10^{-14} \; degrees$

B. $2.1 \times 10^{-4} \; degrees$

C. $1.2 \times 10^{-7} \; degrees$

D. $2.1 \times 10^{-7} \; degrees$

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19#

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The apparent brightness of a st+.l75e zs mzm,w; ftaiar is $1.0 \times 10^{-12} \; W/m^{2}$ and the peak wavelength is 600 nm. Estimate its distance from us. (1.0 分)

A. $0.90 \; pc$

B. $9.0 \; pc$

C. $90 \; pc$

D. $900 \; pc$

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20#

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It can be shown that the approximate age oj u*j8 6/:voar(ft rlxf the universe is 1/H, where H is the Hubble constant. Taking H = 20 km/s/Mva( /uljo 6rfjtxr:8*ly, estimate the age of the universe, in years. (1.0 分)

A. 15 thousand years

B. 15 million years

C. 15 billion years

D. 15 trillion years

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21#

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If a galaxy is moving away from d2 +swxc +x3,qvxfrr -us at 1.0% of the speed of light, how far away is it fro fxqr,wvx+s 3-+x2dcrm us? (1.0 分)

A. 200 ly

B. 200 thousand ly

C. 200 million ly

D. 200 billion ly

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22#

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Estimate the speed of a galaxy that is c5 +zrsq ga0djncdk-4,y:ow /10 billion light-years away. (1.0 分)

A. $0.1 \; c$

B. $0.3 \; c$

C. $0.5 \; c$

D. $0.7 \; c$

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23#

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Estimate the observed wavelength for the 656 nm line in the spe6c n. v+tpq (loep +w-qeu,w5qctrum of a star whicc( -utle+5qqo6 qn.,vp p+ewwh is 100 million light-years from us. (1.0 分)

A. $653 \; nm$

B. $656 \; nm$

C. $659 \; nm$

D. $692 \; nm$

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24#

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About 1 ms after the Big Bang, the temperature of the universe e2yxrgjc l73t-wuyx7-;ef ,l was about 1013 K. What ene 2llceyt77-w-3gey xu; ,x jrfrgy (in eV) does this correspond to? (1.0 分)

A. $1 \; keV$

B. $1 \; MeV$

C. $1 \; GeV$

D. $1 \; TeV$

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