Physics 9 The Solar System Prof. D. Tytler

Second Midterm, Novemeber 14 2000

Please use your code number, NOT NAME.

Always choose the answer which best answers the question.

Please use a soft pencil on a GREEN scantron. We will not re-grade scantrons.

Do not write on the scantron until you know the answer. If you make a change which is not completely erased the machine may not get the correct one. Be careful.

No hats covering your eyes: we must be able to see where you are looking.

You must cover up all answers, including scantrons, at all times. Scantrons must be turned face down when you are not entering an answer. Allowing others to see your answers will be considered cheating.

ANSWERS MAY NOT BE EXACT. CHOOSE THE BEST ONE.

  1. A comet has twice the diameter (eight times the volume) of an asteroid? Which would you expect to be more massive?
    1. Comet – asteroids are made out of rock, which is 3 times as dense as ice, but the comet is 8 times larger
    2. asteroid
    3. equal
    4. not enough known to decide
    5. depends where the comet is in its orbit
  2. A comet and an asteroid of identical mass strike the Earth at the same speed. Which one releases more energy?
    1. comet
    2. asteroid
    3. similar – nearly all of kinetic energy is converted to heat regardless of composition
    4. not enough known to decide
    5. depends on the shape of the orbit
  3. Which of the following lists all of the terrestrial planets?
    1. Mercury, Mars, Saturn, Uranus, Pluto
    2. Mercury, Ceres, Jupiter
    3. Venus, Mars, Earth, Saturn
    4. Earth, Venus, Mercury, Mars
    5. Earth, Moon, Venus, Mars, Phobos, Deimos
  4. Which terrestrial planet has the highest orbital velocity?
    1. Mercury— closest to sun
    2. Mars
    3. Jupiter
    4. Saturn
    5. Earth
  5. The solar system’s largest volcanoes reside on Mars. What does this imply?
    1. Low surface gravity and little plate movement—low gravity doesn’t flatten rock formations, lack of plate movement allows volcano to sit over same hot spot for eons
    2. Hot core with more lava
    3. Less heating from the sun
    4. Fast spin rate
    5. Tidal heating
  6. What property of a planet can be determined using seismology?
    1. Size
    2. Composition
    3. Surface reflectance
    4. Density
    5. both b) and d)—density and composition determine the speed of sound in that material, which is what scientists measure when they time earthquake measurements at different sites
  7. A fictitious planet is the same composition throughout. Which of the following is the least likely cause of thermal heating?
    1. Radioactivity
    2. Differentiation—frictional heating as heavy materials sink through light materials only occurs when a planet is made out of a variety of materials
    3. impacts
    4. tides
    5. solar heating
  8. Spaghetti can be cooked in boiling water at 100 degrees Centigrade for about 10 ten minutes. Is it possible to cook spaghetti in the open air on Mars?
    1. Yes, you would cook spaghetti just like on Earth
    2. No, Mars’ thin atmosphere permits far too much radiation to reach surface
    3. No, Mars’ weak gravity could not contain water in liquid state
    4. Yes, the water would not evaporate because there is no atmosphere to conduct heat
    5. No, there is insufficient atmospheric pressure to maintain water in liquid form—gravity keeps the water in the bottom of the pot, but it is air pressure that keeps it in a liquid state
  9. A terrestrial planet is seen overhead at midnight. Which planet is it?
    1. Mercury
    2. Mars—only terrestrial planet farther from sun than Earth; Jupiter is not a terrestrial planet
    3. Jupiter
    4. Could be B or C
    5. Venus
  10. What could you do with the following formula: v/c = (lambda1 – lambda0)/lambda0?
    1. Determine the radial velocity of a planet—this is the Doppler shift formula
    2. The mass of a planet
    3. Temperature of a solid
    4. The angular size of a star if you knew its distance
    5. None of the above
  11. Why does the moon have a larger tidal effect on the Earth than the Sun?
    1. The sun’s light counteracts its gravity
    2. The moon is nearer—tidal forces are highly sensitive to distance
    3. The moon is moving faster than the sun
    4. The sun is gaseous
    5. The moon spins on its axis once each orbit of the Earth
  12. Why aren’t there volcanoes on Mercury?
    1. It is small—meaning it cooled rapidly, so there is no molten core
    2. It has no magnetic field
    3. It is too close to the sun
    4. There are volcanoes on mercury
    5. Answer not yet known at this time
  13. What is an easy way to determine the presence of life?
    1. Temperature – life supporting planets are warmer
    2. Density – life supporting planets are higher density
    3. Atmospheric composition – life greatly alters chemical abundances – life has produced large quantities of 02 , which does not appear on other planets
    4. All of the above
    5. None of the above
  14. Why are sunspots dark?
    1. Clouds in sun’s atmosphere block light
    2. Clouds in earth’s atmosphere block light
    3. both a) and b)
    4. they are cooler than surrounding gas—sun spots last days, clouds do not. Also, there are no clouds in suns hot atmosphere. Colder objects don’t radiate as much heat.
    5. not known at this time
  15. How do we know that the dark lowlands on the moon are younger than the highlands?
    1. Lowlands have more large craters
    2. Lowlands mostly face the earth
    3. More active volcanoes in the lowlands
    4. More heat comes from the lowlands
    5. Rocks collected have younger ages—Apollo missions
  16. At which phases(s) of the moon are solar eclipses observed?
    1. Full
    2. New—only time moon between sun and earth
    3. first quarter
    4. crescent
    5. both a and b
  17. How do we measure the chemical composition of the atmosphere of a planet?
    1. Analyze its orbit
    2. Analyze the absorption lines in its spectrum—specific lines indicate specific elements
    3. Determine its distance from the sun
    4. Determine the peak in the distribution of its light
    5. Measure the variation in its brightness over time
  18. Why is Venus’ surface hotter than the Earth’s?
    1. Venus in nearer the sun
    2. Venus spins very slowly
    3. Venus’ surface is nearly flat
    4. Venus has much more efficient winds
    5. Venus’ atmosphere contains lots of CO2 – runaway greenhouse effect
  19. What is the origin of winds on the Earth?
    1. Uneven heating of the surface by sunlight
    2. Shape of earth’s orbit
    3. Inhomogeneous (not same everywhere) chemical composition of atmosphere
    4. Solar wind
    5. Long term climate change
  20. Which of the following has the oldest surface?
    1. Earth
    2. Oort cloud comet—only primordial, unaltered surface. Surfaces of planets and moons were greatly altered by heavy bombardment billions of years ago. Meteorites blasted off Mars and heated by Earth’s atmosphere during entry are also metamorphized
    3. Venus
    4. Moon
    5. Meteorite from mars
  21. Why are asteroids often far from spherical in shape?
    1. Rapid rotation periods
    2. Weak gravity—asteroids are much smaller than planets, so their gravity is far too weak to pull them to a spherical shape
    3. Frequent impacts
    4. Lack of atmosphere
    5. Lack of water erosion
  22. Figure 1 shows the Big Dipper as seen from one place at two different times. It has rotated about 90 degrees. What is the difference between the two times?
    1. 3 hours
    2. 4 hours
    3. 6 hours—the earth rotates once (360 degrees) every 24 hours, making objects appear to move around the sky; 90 degrees is a quarter of 360 as 6 hours is a quarter of a day
    4. 8 hours
    5. 12 hours