NSCI111 Midterm Math Review Problems

Note: The math questions on the test should be relatively easy compared to these.

  1. If an object 1 AU in size subtends 1 second of arc in the sky, how distant is it (in km?) Remember that 60 seconds of arc = 1 minute of arc, 60 minutes of arc = 1 degree, and 1 AU = 150 million km. Express your answer using scientific notation.
    Answer: 3.09x1013 km
    Note: This defines the parsec distance unit.
  2. Phobos orbits Mars at a mean distance of 9378 km, and Deimos orbits Mars at a mean distance of 23,459 km. If Deimos completes one orbit in 1.262 Earth days, how long does Phobos take to complete one orbit? In what direction should the Mars Pathfinder have seen Phobos rise? Why? (One Mars day = 1.08 Earth days.)
    Answer: Phobos completes one orbit in 0.319 days, and should have risen in the West since Phobos moves through the sky faster than Mars rotates.
  3. Mars has a mass 0.108 times that of Earth. The radius of Mars is 3388 km, and the radius of Earth is 6371 km. If a gallon of water weighs 8.3 lbs. in Houston, how much would that same gallon of water weigh in a human habitat on Mars?
    Answer: 3.2 lbs.