Astronomy 10 – Summer 2009 – Instructor Tony PiroMidterm Exam Title Page———————————————————————————————————————————————Print name:Sign name: Student ID#:Print and sign your name on your SCAN-TRON 8 82 form. Under “subject,” please put your Student ID #.———————————————————————————————————————————————THIS TEST IS CLO SED BOOK, CLOSED NOTES, AND NO CALCULATORS!Mark all answers on a SCAN-TRON 882 form. Use a # 2 pencil. Completely fill in the appropriatebubble. Be sure to properly er ase all altered answers and stray marks!For true/false questions, mark bubble A if the statement is true and bubble B if false. For multiplechoice questions, mark the bubble corr e sponding to the answer you think best answers the question.All 40 questions carry equal weight. Read each question carefully before answering. There is no penaltyfor guessing. If you need extra room for your work, you can use the last (blank) page.Before leaving the c lassroom, be sure you turn in both your SCAN-TRON form and this multi-page setof questions. You have until 12 o’clock to complete the exa m. Budget your time appropriately. Good luck!———————————————————————————————————————————————Possibly Useful Informationd = vt density ρ = M/V c = 3 × 108m/sFor a sphere, V =43πR3and A = 4πR2For a circle, A = πR2, C = 2πR π ≈ 3.14There are about 3.2 × 107seconds in every year and 8.64 × 104(roughly 105) seconds per day.Kelvin = Celsius + 273 Fahrenheit = (9/5) Celsius + 321 A. U. = 1.5 × 108km 1 light year (ly) ≈ 63, 000 A. U. ≈ 9.5 × 1012km ≈ 1013km1 pc = 3.26 ly ≈ 3 × 1018cm ≈ 3 × 1013km 1˚A= 10−8cm = 10−10m60′′(arcsec) = 1′(arcmin) 60′= 1◦(degree) 360◦= full circle = 2π radians = 24 hoursλpeakT ≈ 3 × 107˚A K = 0.3 cm K λν = c P = 1/ν resolution ∝ λ/Denergy/area/sec = σT4luminosity = energy/sec = 4πR2σT4(for a sphere)E = hν F = GM1M2/d2(λ − λ0)/λ0= ∆λ/λ0= v/cP2= kR3where k ≈ constant ≈ 4π2/(GM1) if M1≫ M2In general, P2= (4π2R3)/[G(M1+ M2)] For planets, v ∝ 1/√R12Astronomy 10 – Summer 2009 – Instructor Tony PiroMidterm Exam(1) T or F. The planet Venus can be seen in a dark night sky, around midnight, from Berkeley during someportions of the year.(2) If the Earth’s radius were incre ased by a fa c tor of 3, and the Earth’s mass were increased by a factor of3, how much would you weigh while standing on the new (larger) surface of the Earth?(a) 9 times as much(b) 3 times as much(c) 1/3 as much(d) 1/9 as much(e) You weight would remain unchanged(3) Ultraviolet light from a star is measured to have a wavelength of 1500˚A. What is its approximatefrequency?(a) 2 × 1015Hz(b) 2 × 105Hz(c) 4.5 × 1013Hz(d) 4.5 × 101Hz(e) 4.5 × 106Hz(4) Which one of the following statements is an advantage that reflecting telescopes have over refractingtelescopes?(a) Reflecting telescopes can see farther than a refra c ting telescope s with the same diameter.(b) Reflecting telescopes magnify light from distant stars better than re fracting telescopes.(c) Reflecting telescopes do not suffer from chromatic aberration.(d) Reflecting telescopes are less affected by dust in the atmosphere than refracting telescopes.(e) Reflecting telescopes are better for impressing girls .(5) T or F. If you double a star’s radius and keep the temperature fixed, it will increase the luminosity mo rethan if you double the star’s temperature and keep the radius fixed.(6) If you are in Berkeley in the winter and you see that the Moon is full, then at what time did the Moonrise that day?(a) 6 am(b) 6 pm(c) 9 am(d) 9 pm(e) noon(7) According to Kepler’s first law, the orbits of planets are ellipses with the Sun at one focus. In the caseof Jupiter, what is at the other focus?(a) Nothing(b) Jupiter’s moon, Io(c) Mars(d) Saturn(e) The asteroid belt(8) If you wanted to prevent the Earth from having seasons, what could you do?(a) Align the Earth’s rotation axis to be perpendicular with resp e c t to its orbital plane.(b) Align the Earth’s rotation axis to be par allel with respect to its orbital plane.(c) Change the Earth’s o rbit to be circular.(d) Increase the semimajor axis of Earth’s orbit.(e) None of the above.3(9) T o r F. If the surfa ce temperature of Star Harpo is 3 times that of Star Zeppo, then the fr e quency atwhich Star Harpo ’s spectrum peaks is 1/3 the frequency at which Star Zeppo’s spectrum peaks.(10) Which one of the following statements about the terres trial planets is FALSE?(a) They are denser than water.(b) They have radii that are equal to or less than Earth.(c) They all appear in the sky within 1 to 2 hours before sunrise or after sunset.(d) They have masse s that are equal to or less than Earth.(e) They have rocky outer parts and iron cores.(11) If the age of the Earth (about 5 billion years) were compressed into one day, the length of time sinceearly hominids have been around (ab out 5 million years ago) would be approximately(a) 100 seconds(b) 1 hour(c) 12 hours(d) 104seconds(e) 30 minutes(12) T or F. A light year is a unit of distance.(13) Which one of the following statements about light (electromagnetic waves) is TRUE?(a) Different wavelengths of light move at different speeds within a prism.(b) X-rays move at higher speeds than ultraviolet radiation in a vacuum.(c) Light emitted from sourc e moving toward you is blueshifted and travels faster than redshifted light.(d) Red light has the same frequency but a differe nt wavelength than blue light.(e) Infrared radiation has the longest wavelength possible for light.(14) Saturn is approximately 9 times fa rther from the Sun than the Earth. By what facto r is Saturn’s velocitydifferent than the Earth’s veloc ity?(a) 1/3(b) 3(c) 1/9(d) 9(e) 4.5(15) T or F. The Moon is able to cover the Sun and create a total solar eclipse because the Moon’s angularsize, with respect to the Earth, is much less than the Sun’s angula r size.(16) Which one of the following statements about twinkling is FALSE?(a) Stars twinkle more when they are near the horizon than when they are high in the sky.(b) Stars would twinkle if viewed by an observer on the surface of Mars.(c) A star twinkles more than a planet because the star is
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