Question

1. [13 marks total]

   1. (a) [1] Suppose on the Moon, a meteoroid creates a crater in the shape of a hemisphere with a radius of 1 km.

      Calculate the mass of material excavated, assuming a density of 1920 kg/m3 for regolith.

   2. (b) [1]When the meteoroid makes the crater,the excavated material is raised vertically by a distance equal to the

      radius of the crater, 1 km. Calculate the potential energy required to lift the material.

   3. (c) [3] The meteoroid that created the crater was spherical and made of rock, and it had an impact velocity of

      5 km/s. Assuming that energy was conserved in the collision, what was the size of the meteoroid?

   4. (d) [5] Comets have a density of one third the value of rocky meteoroids, but can travel three times as fast. If a comet the same size of the meteoroid had impacted and caused the crater, with a density of 1000 kg/m3 and an impact velocity of 15 km/s, what size crater would have been made? Would it be larger or smaller than that made by a rocky meteoroid?

   5. (e) [3] Consider the material excavated by the impactor, the ejecta. Ejecta blankets are found on both Mercury and the Moon, but on Mercury, the ejecta is generally much closer to the crater compared to the Moon. Explain why this is.

Answer 1