University of Michigan - Department of Astronomy


Craters - Worksheets


Mass of the Ball Bearing:______________

Table 1: Cratering parameters and calculations

Height of drop Crater Diameter
Impact Energy [Joules] Log(Energy) Log(Diameter)

Equation and sample calculation of the impact energy (check this with your GSI before filling out the table).

Your values:

Activity #1 Questions:

  1. The impact energy is actually the kinetic energy the ball hit the sand with. What was the impact energy of the ball when dropped from the greatest height in your experimant? Use this and the equation for kinetic energy given in the introduction to calculate the speed it was traveling when it hit the sand. Show your work.
    Impact E = _________________

  2. The diameter of the crater from the asteroid that probably killed the dinosaurs is about 180 km. According to your model, how much kinetic energy did that asteroid have when it hit the Earth? Show your work.

  3. A good estimate for the velocity (based on observations of other imapcts) of this asteroid when it hit the Earth would be about 20 km/s. What was the mass of the asteroid? Show your work.

  4. Assuming a density of about 3 gm/cm^3 = 3000 kg/m^3 (an average density for asteroids) and a roughly spherical shape, what was the radius of the asteroid? (density of a sphere = ).

  5. Does this size seem reasonable for a dinosaur-killer asteroid (both in terms of the crater size and what is present in the asteroid belt)? Explain (note especially the size of the crater and your answer to question 1!)

  6. What do you think was your greatest source of error in determining the size of the asteroid?

Activity #2 Questions:

  1. As you dropped the marbles from different heights, how did the ejecta (material tossed out of the crater) change?

  2. When you dropped non-spherical objects, or threw the marble at an angle, how did the shape and ejecta change? How does this relate to craters seen on other planets/moons?

  3. If you were to look at another group's sandbox, could you tell which craters were made first (‘older’)? How?

  4. Describe the transformation of energy that takes place during the formation of an impact crater (from approach of the meteorite to after the crater is formed).

  5. Draw an impact crater, from top and side view.

  6. By looking at craters astronomers can get an idea of conditions on another planet/moon without even going there. Below are images of the four Galilean moons of Jupiter. Place them in order from oldest to youngest surface terrain. Explain how you figured out what order to put them in. Based only on the pictures, which one(s) are most likely to be geologically active? Why (note none of them have a substantial atmosphere)? (If you are looking at the lab online you can right-click or control-click to open the full sized image)
    Callisto Europa
    Ganymede Io