Physics Unit33: Astrophysics and Cosmology - 51fly国际课程 (51fly.win)

1#

The appearance of the great range of brightness k*9:g(: 4/yvqs-eekvunc gnc among stars is due to

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#

单选题 ( 1.0 分) 切至单题模式搜藏此题

The absolute luminosity for moosl00 o*9)l (-sq hdc(q71lbpxjnhys st stars depends on the

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#

单选题 ( 1.0 分) 切至单题模式搜藏此题

Four different main-sequence stars are colored blue.dko; h.hu5o l, orange, red, and yellow. What is their rank fuo; d.h.5lokh rom coolest to hottest?

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#

单选题 ( 1.0 分) 切至单题模式搜藏此题

A Hertzsprung-Russell m9r2;d0e aa5c pfrbt,diagram shows stars on a plot of

A. apparent brightness vs. temperature.

B. luminosity vs. temperature.

C. luminosity vs. distance.

D. magnitude vs. apparent brightness.

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5#

单选题 ( 1.0 分) 切至单题模式搜藏此题

A white dwarf star with a 5j0bt+if.xc49kpbhs pkv ,1imass equal to that of the Sun is about the size of

A. the Sun.

B. the Earth.

C. a basketball.

D. a baseball.

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6#

单选题 ( 1.0 分) 切至单题模式搜藏此题

The Chandrasekhar limit of stellar mass (below which a star wil.jsbbg 8vys0e 2ezeq /h/l ;r1l collapse into a white dwarf) is, if the mass of our Sun is z8 reeqs.ye gb2v/1 bjl/;h0s M, about

A. 0.8 M.

B. 1.2 M.

C. 1.4 M.

D. 1.9 M.

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7#

单选题 ( 1.0 分) 切至单题模式搜藏此题

Supernovas are thought tkz43-mccc()g ym pjn( o always result in

A. neutron stars.

B. red giant stars.

C. regular stars like our Sun.

D. white dwarfs.

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8#

单选题 ( 1.0 分) 切至单题模式搜藏此题

Black holes

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#

单选题 ( 1.0 分) 切至单题模式搜藏此题

Pulsars are rapidly spinninm*q 1lnb3 dl4mg

A. regular stars like our Sun.

B. red giant stars.

C. neutron stars.

D. white dwarfs.

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10#

问答题 ( 1.0 分) 切至单题模式搜藏此题

State Einstein's principle of equivalence.euclb82pkzx y 5o4((. ztnzj-mj7)u c

该题自我估分: (必填) (满分:1.0分)

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11#

单选题 ( 1.0 分) 切至单题模式搜藏此题

The Schwarzschild radius of a black h 4gea tze,b q6fe7ir,*p 9qtuqb.rt*vt;.9e nole is that radial distance from the center of a sphere within which not even light can escape. It was first discovered math.ap qe t9e,;gt*t 7i.6v qbreb4ferz*,n tuq9ematically by Schwarzschild in 1916 after Einstein published his general relativity 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

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12#

单选题 ( 1.0 分) 切至单题模式搜藏此题

When a distant source emits light of a particular waveleng; xd-h,(9lnynx; at mfth in the visible, and the source is moving ahd ;xf;n tnm(x-9l ,yaway from us, the color of the light appears to us to be shifted toward the

A. red end of the visible spectrum.

B. blue end of the visible spectrum.

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13#

单选题 ( 1.0 分) 切至单题模式搜藏此题

The cosmic background radiation corresponds to a temper j,ni qww+x )3qp0sv9zature of about

A. 1.4 K.

B. 2.7 K.

C. 3.0 K.

D. 3.3 K.

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14#

单选题 ( 1.0 分) 切至单题模式搜藏此题

The Sun has apparent brightness at4 awij8xc,s+sjm x8 /h 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?

A. $0.25 \; B$

B. $0.063 \; B$

C. $0.025 \; B$

D. $0.00063 \; B$

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15#

单选题 ( 1.0 分) 切至单题模式搜藏此题

A star has absolute luminosity cys7 j f- h gzg1gk*om2+h8w9lequal to that of the Sun ($1.5 \times 10^{8} \; km$ from the Earth) but is 10 pc away from the Earth. By what factor will it appear dimmer than the Sun?

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#

单选题 ( 1.0 分) 切至单题模式搜藏此题

The Earth's orbit has a mean radius .6tx7w;b-hqxmo)xyx o+e s )eof $1.5 \times 10^{8} \; km$. 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?

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#

单选题 ( 1.0 分) 切至单题模式搜藏此题

The Earth's orbit has a mean radius+6lv2hnq8mtr 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 = $9.46 \times 10^{15} \; m$)

A. $0.13 \; ly$

B. $1.3 \; ly$

C. $13 \; ly$

D. $130 \; ly$

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18#

单选题 ( 1.0 分) 切至单题模式搜藏此题

What is the parallax angle for.5s bvw8l vvb) Proxima Centauri, which is Earth's nearest star at 4.3 lw5vsl. 8vvbb )y?

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#

单选题 ( 1.0 分) 切至单题模式搜藏此题

The apparent brightness of a star i8dh-qms )jn i. fjri,t(i bolr+,x(v- s $1.0 \times 10^{-12} \; W/m^{2}$ and the peak wavelength is 600 nm. Estimate its distance from us.

A. $0.90 \; pc$

B. $9.0 \; pc$

C. $90 \; pc$

D. $900 \; pc$

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20#

单选题 ( 1.0 分) 切至单题模式搜藏此题

It can be shown that the approxv:h*s ,k(fb 3p lsag5.kwz6zzimate age of the universe is 1/H, where H is the Hubble constant. Taking H = 20 km/s/Mly, .zlbw vkh,*zag3z( 5pf :sk6sestimate the age of the universe, in years.

A. 15 thousand years

B. 15 million years

C. 15 billion years

D. 15 trillion years

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21#

单选题 ( 1.0 分) 切至单题模式搜藏此题

If a galaxy is moving away from us at 1.0% of the speed of ,bun 5e,bb+yxtf d6;xw ep snlp0en;w;0gu7) light, how far away is it fg6; x50;s0bfb ep7edw ; nn, tyu+pwx),lnb uerom us?

A. 200 ly

B. 200 thousand ly

C. 200 million ly

D. 200 billion ly

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22#

单选题 ( 1.0 分) 切至单题模式搜藏此题

Estimate the speed of a galaxy that is 10 billion light-years awayk9ohv ftl7f4c/2 j9 q7/3qsj w/selta.

A. $0.1 \; c$

B. $0.3 \; c$

C. $0.5 \; c$

D. $0.7 \; c$

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23#

单选题 ( 1.0 分) 切至单题模式搜藏此题

Estimate the observed wavelength for the 656 nm line in the spectrum of a sta.,l( ihj)ab3j sous1 kzmp;m.r which is 100 millioz)mj,jos.1 a ui(mhkl;bsp 3 .n light-years from us.

A. $653 \; nm$

B. $656 \; nm$

C. $659 \; nm$

D. $692 \; nm$

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24#

单选题 ( 1.0 分) 切至单题模式搜藏此题

About 1 ms after the Bb; l*vmpv dw(tn f7t7g1q9 cz7ig Bang, the temperature of the universe was about 1013 K. What energy (in eV7g tl q 97fw ;btd*1c7mvzvnp() does this correspond to?

A. $1 \; keV$

B. $1 \; MeV$

C. $1 \; GeV$

D. $1 \; TeV$

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