Homework #6

Homework due in class, Nov 14. Remember to show your work, neatly.

1) A 100 kg meteor falls on to the Moon's surface.

  • Assume the meteor starts at rest, very far away. Calculate its kinetic energy as it strikes the surface (hint: it will be equal to the potential energy that it had very far away) (4 points) (Answer=2.7x10^8 J)
  • Assume that the material on the surface is thrown 10 meters in the air (or no air as the case may be). Also assume the density of the surface is 3 gm/cc. How big is the crater (in volume) (4 points) (V=5.6x10^9 cc, or radius=1781 cm)
  • Do the above calculations again for Mercury (4 points)

    2) If the core of a planet is 0.3 times the radius of the planet with a density of 17 gm/cc, and the mantle has a density of 5 gm/cc, what is the mean density of the planet? (4 points) (Answer= 5.3 gm/cc)

    3) If the mass of Earth's atmosphere is 5x10^18 kg and all the volcanes put out 10^9 kg of H2O per year, how long to change the Earth's atmosphere from 1% to 2% H2O (assume a balance between rainfall and evaporation) (4 points) (Answer=51 million years)

    4) A terraforming unit produces 10^10 kg of O2 per day. How long to convert Mar's atmosphere into an Earth-like composition. Assume the mass of Mars atmosphere is 1/10 the Earth's. (4 points) (Answer=34,000 years)