Title: Craters

Purpose: To identify the factors of cratering

Materials: 1 large tray, sand or flour, 2-3 balls of the same size but of different mass, 2-3 balls of different size, ruler, meter stick, salt or colored sand, balance

Background: Since the formation of the solar system, meteorites have been forming impact craters on the surface of all the solid planets and their moons. This process has been important in the evolution of the planets. Cratering caused early melting on the planets and excavated fresh sub-surface material. The surfaces of some of the interior planets and moons of the solar system are almost covered entirely with impact craters. The nearest example of a heavily cratered surface is the Earth’s own moon. It has preserved many of the craters formed by the meteorites that have impacted it since its formation. The last stage of planetary formation, about 3.9 billion years ago, is when the Moon acquired most of its craters. At this time in the history of the solar system, there was an abundance of rock, ice, gas, and debris pieces floating in space, crashing into any terrestrial surface in the area. The craters formed on Earth at the time have long since been destroyed by geologic processes such as weather, erosion and continental drift. After 3.9 billion years, the number of meteorites loose in our part of space decreased to what it is today.

Procedure: Part I How mass affects impact craters

1.  Fill the tray with sand approximately 1cm deep

2.  Smooth the sand out and sprinkle a thin layer of salt.

3.  Find the mass of the 2 marbles that are of the same diameter. (the small ones)

4.  Separately mass out the balls/marbles to the nearest .10 g.

5.  Drop the first ball/marble from a distance of 1 m above the sand, measure the diameter of the crater and record in the data table.

6.  Repeat with ball/marble 2 and 3. Answer questions 1-3 in the obs./anal./conc. section of the lab.

Part II How speed of meteorites affects impact craters

1.  Take one of the small marbles.

2.  Smooth out the sand and sprinkle a thin, fresh layer of salt/colored sand over the original layer.

3.  Drop the marble from 10 cm, record the crater diameter on the chart.

4.  Drop the marble from 1 m, record the crater diameter on the chart.

5.  Drop the marble from 2 m, record the crater diameter on the chart. Answer questions 4-6 in the obs./anal./concl. section of the lab.

Part III How size of meteorites affects impact craters.

1.  Take out 2 or 3 different sized balls/marbles

2.  Smooth out the sand and sprinkle a fresh, thin layer of salt/colored sand on top of the original layer(s).

3.  Drop each marble/ball from a distance of 1 m and record the diameter of the crater in the chart. Answer questions 7-9 in the obs./anal./conc. section of the lab sheet.

Part IV Crater structure

1.  Sketch in the data section at least one top view and one side view of a crater. Label and color the differences in the material ejected from the crater.

Data:

Mass affect on craters

Object / Mass (g) / Distance (cm) / Crater Diameter (cm)
#1
#2

Speed affect on craters

Object / Velocity (cm/s) / Distance (cm) / Crater Diameter (cm)
#1 / 140
#2 / 443
#3 / 626

Size affect on craters

Object / Distance (cm) / Crater Diameter (cm)
Small / 100
Medium / 100
Large / 100

Sketch: Top View Side View

Observation/Analysis/Conclusion:

1.  Compare your 2 or 3 craters. Which crater is the largest?

2.  What is the only difference in the ‘meteors’ that were used?

3.  Finish this statement: The ______the mass, the ______the crater.

4.  Compare your craters. Which is the largest?

5.  What is the only difference in the way you made the craters?

6.  Finish this statement: The ______the velocity, the ______the crater.

7.  Compare your craters. Which is the largest?

8.  What is the only difference in the way you made the craters?

9.  Finish this statement: The ______the marble, the ______the crater.

10.  How is this model different than what would really happen as a meteor hit the surface of a moon or the Earth?

11.  What does an impact do to the rock layers on the surface of a moon or planet?

Optional: Kinetic and Potential Energy

In this activity there are two types of energy involved in the marble’s fall, kinetic and potential.

When you hold the marble above the sand, it has a mass and gravity is puling down on it. Believe it or not, this marble has energy as you hold it there, the energy is called potential energy. It is the energy representing the force of the Earth’s gravitational pull. As you drop the marble, kinetic energy keeps the object in motion.

PE = mass x height x gravity or PE = mhg

The gravity is 9.8 m/s/s or 980 cm/s/s (use this number as your gravity)

1.  Calculate the PE for the objects in the second data table.

a.

b.

c.

When you released the marbles they no longer had the same potential energy, in fact as they fell, their potential energy became kinetic energy. Kinetic energy is the energy of bodies in motion the formula for kinetic energy is:

KE = ½ mass x velocity2 or KE = 1/2mv2

2.  Calculate the KE for each object in the second data table.

a.

b.

c.

A.  What do you notice about the number of the PE compared to the numbers of the KE?

B.  Explain the connection.