Materials Included In Kit

Additional Materials Required

Prelab Preparation

The sand may be divided into eight equal portions. Approximately 500 g will fill each large weighing dish. The portioned sand may be added to beakers or large plastic cups so students can easily pour the sand into their respective dishes.

Safety Precautions

Wear safety glasses during this investigation. Please follow all laboratory safety guidelines. Please review current Safety Data Sheets for additional safety, handling and disposal information.

Disposal

Please consult your current Flinn Scientific Catalog/Reference Manual for general guidelines and specific procedures, and review all federal, state and local regulations that may apply, before proceeding. Sand may be saved for future use.

Lab Hints

• Enough materials are provided in this kit for eight student groups. This is a Super Value Kit—all the materials included are completely reusable.
• This laboratory activity can reasonably be completed in one 50-minute class period. The prelaboratory questions may be completed before coming to lab, and the post-laboratory questions may be completed the day after the lab.
• If time is a factor, students may enter the data in Part I for the 1.9-cm steel sphere dropped from 30 cm in the appropriate places in the data tables for Parts II and III without repeating the drops.
• Any box lid or pan that is 5 or more cm larger on each side than the weighing dish may be used to catch sand that is scattered outside the dish from the impact of the spheres. A shallow container is best so students can see the measured depth of the craters at eye level.
• Students may be able to make more than one drop before smoothing the sand again, as long as the impact crater from one drop does not overlap with the crater from another drop.

Teacher Tips

• This activity has applications for units on astronomy, measurement, and kinetic energy.
• For photos of lunar craters, visit the Lunar and Planetary Institute website at http://www.lpi.usra.edu/education/explore/LRO/activities/craterCreations/Lunar_Crater_Images.pdf (accessed July 2018).
• Demonstrate ejecta rays by filling a weighing dish or other shallow pan with white flour, and then sift cocoa powder or dark-colored dry tempura paint evenly over the top for the target material. Drop a steel sphere from 30 or more cm and observe the impact crater. The lighter-colored flour that is ejected often forms rays around the crater. Repeat by leveling the flour and adding more cocoa powder or paint on top.
• A common misconception about meteors is that friction from the atmosphere causes them to burn up before they reach the Earth’s surface. However, these high-speed space objects create a shock wave as they move through the atmosphere. This shock wave is generated by the meteor vigorously compressing the air in front of it, which heats the air. The hot air flowing around the meteor causes the meteor to heat up.

Answers to Prelab Questions

1. One variable that will be investigated is the density of the impactor. Density = mass/volume.
   1. The equation for the volume of a sphere is V = 4/3πr³, where r is the radius. Determine the volume of the 1.9-cm diameter spheres that will be used as impactors in Part A of the Procedure and record the volume for Data Table A on the Investigating Impact Craters Worksheet.

      V = 4/3π(0.95 cm)³ = 3.6 cm³

   2. Briefly describe how the density of each sphere used in Part A of the Procedure will be determined.

      Each sphere will be massed in grams. The mass will then be divided by the calculated volume of the sphere to obtain the density in g/cm³.

2. In Part B of the Procedure, steel spheres with different diameters will be used as impactors.
   1. Complete the following statement, “If the diameter of a solid steel sphere is increased, then the mass of the sphere will increase because if the diameter increases, then the amount of matter must also increase.
   2. Complete the following statement, “If the diameter of a solid steel sphere is increased, then the density of the sphere will remain the same because density is a property of matter—mass/volume. As long as the composition of the steel remains the same, the density would remain the same.

Sample Data

Table A. Density of Impactor
Drop height: ___30___ cm 
Volume: ___3.6___ cm³

Answers to Questions

1. Calculate the average crater diameter and depth for each test and record the respective averages in the data tables above.

   Sample calculation: (1.1 cm + 1.8 cm + 1.4 cm)/3 = 1.4 cm

2. In general, how does the diameter of the crater compare to the diameter of the impactor?

   With the exception of the polystyrene sphere, the diameter of the crater is two to three times larger than the diameter of the impactor.

3. What was the effect of the density of the impactor on the size of the crater?

   As the density of the impactor increased, the diameter and the depth of the crater also increased.

4. Find two spheres of similar mass but different diameters and compare their results.
   1. Does the mass or the diameter of the impactor seem to have a greater effect on the diameter and depth of the crater?

      The 1.9-cm diameter glass sphere and the 1.3-cm diameter steel sphere have similar masses. The diameter and depth of their respective craters were nearly identical. Therefore, the mass of the impactor is a greater factor than diameter.

   2. Explain your answer to 4a in terms of kinetic energy.

      Kinetic energy is directly proportional to the mass of an object (and its velocity squared). The greater the mass, the more kinetic energy the impactor has. This kinetic energy would be transferred to the target upon impact.

5. Compare and contrast features of the experimental impact craters to actual impact craters.

   The experimental impact craters were circular and had a rim around the outer edge, similar to actual impact craters. The impactor remained intact in the center of the crater during the experiment, where most actual impactors disintegrate upon impact. The experimental target material was uniform, so rays were not very evident.

References

Exploring the Moon: A Teacher’s Guide for Earth and Space Sciences. NASA. [Online] November, 1997, pp. 61–70. (accessed January 2014).

Introduction

Gaze at a full moon on a clear night and notice the circular features that can easily be seen. These circles are impact craters, depressions in the surface created when debris from space hit the Moon. In this activity, investigate factors that can affect the appearance of impact craters.

Concepts

• Kinetic energy
• Meteorites
• Impact craters

Background

Many objects in the Solar System, such as the terrestrial planets, other moons and asteroids, exhibit impact craters. The object creating the crater is called an impactor. Most impactors are meteoroids, small rocky or metallic objects traveling through space. When a meteoroid enters the Earth’s atmosphere, it is called a meteor. Meteors often disintegrate as they travel through the Earth’s atmosphere, but a portion of some meteors may strike the surface. Any fragment of a meteor that survives the impact is called a meteorite. Since the Moon has no atmosphere, its surface is impacted more frequently than the Earth. In addition, without wind or water erosion, the features of lunar impact craters remain evident for a longer period of time. Scientists once thought most craters on the Moon originated from volcanoes, but by studying Earth’s impact craters—such as Meteor Crater in Arizona—they have identified similar features on the Moon as impact craters.

The kinetic energy of an object is equal to ½ mv², where m = mass and v = velocity. Since an impactor travels at a high rate of speed due to the acceleration of gravity, the impact event is usually explosive, which is why most impact craters are circular, no matter the shape of the meteorite. Only impactors that strike the surface at a very low angle form elongated craters. Most of the impactor matter is vaporized by high-pressure shock waves. The collision and explosion create a crater in which the target material is compressed, displaced, and ejected. The blanket of material that is thrown out of the crater—ejecta—is thicker nearer the crater. Some of the ejecta form a rim around the outer edge of the crater. Other ejected matter may form rays—streaks of fine material thrown out from the crater in a radial pattern like spokes on a wheel. When the crater ejecta material is more reflective than the surrounding landscape, the rays are clearly visible (see Figure 1).

Experiment Overview

The purpose of this activity is to investigate factors that affect the diameter and depth of impact craters. The density of the impactor will be investigated in Part A, the diameter in Part B and the speed of the impactor in Part C.

Materials

Prelab Questions

1. One variable that will be investigated is the density of the impactor. Density = mass/volume.
   1. The equation for the volume of a sphere is V = 4/3πr³, where r is the radius. Determine the volume of the 1.9-cm diameter spheres that will be used as impactors in Part A of the Procedure and record the volume for Data Table A on the Investigating Impact Craters Worksheet.
   2. Briefly describe how the density of each sphere used in Part A of the Procedure can be determined.
2. In Part B of the Procedure, steel spheres with different diameters will be used as impactors.
   1. Complete the following statement, “If the diameter of a solid steel sphere is increased, then the mass of the sphere will (increase/decrease/remain the same) because _______________________________________________________.
   2. Complete the following statement, “If the diameter of a solid steel sphere is increased, then the density of the sphere will (increase/decrease/remain the same) because _______________________________________________________.

Safety Precautions

Wear safety glasses during this investigation. Please follow all laboratory safety guidelines.

Procedure

Part A. Density of Impactor

1. Place the plastic dish in the center of a shallow box or tray.
2. Carefully fill the dish to the top with sand.
3. Gently shake the dish back and forth to level the sand. Use the metric ruler to smooth the sand so it is even with the top of the dish (see Figure 2).
   {12379_Procedure_Figure_2}
4. One team member should hold the meter stick vertically so the zero end is on the work surface.
5. Another team member should hold the 1.9-cm diameter polystyrene sphere 30 cm above the top of the sand. Note: Be sure to measure 30 cm from the top of the sand, not from the work surface.
6. Drop the sphere onto the sand.
7. Carefully remove the sphere from the sand, taking care to disturb the crater as little as possible.
8. Use the metric ruler to measure the diameter of the crater from the top of the “rim” on one side to the top of the “rim” straight across.
9. Record the diameter on the Investigating Impact Craters worksheet in Data Table A.
10. Measure and record the depth of the crater. Note: If the zero mark on the ruler is not at the edge, the ruler will need to be carefully inserted into the sand until the zero mark is even with the bottom of the crater.
11. Repeat steps 3–10 for two more trials with the same sphere.
12. Repeat steps 3–11 with the 1.9-cm glass sphere.
13. Repeat steps 3–11 with the 1.9-cm steel sphere. Note: Use the two disk magnets to remove the steel sphere from the sand without disturbing the crater (see Figure 3).
    {12379_Procedure_Figure_3}
14. Mass each sphere from Part A on a balance.
    1. Record the mass of each sphere in Data Table A.
    2. Calculate the density of each sphere using the volume calculated in Prelab Question 1a.
    3. Record the density of each sphere in Data Table A.

1. Level the sand in the dish as in step 1 of Part A.
2. One team member should hold the meter stick vertically so the zero end is on the work surface.
3. Another team member should hold the 1.3-cm steel sphere 30 cm above the top of the sand. Note: Be sure to measure 30 cm from the top of the sand, not from the work surface.
4. Drop the sphere onto the sand.
5. Use the two disk magnets to carefully remove the sphere from the sand, taking care to disturb the crater as little as possible.
6. Use the metric ruler to measure the diameter of the crater from the top of the “rim” on one side to the top of the “rim” straight across.
7. Record the diameter on the Investigating Impact Craters worksheet in Data Table B.
8. Use the metric ruler to measure the depth of the crater. Note: If the zero mark on the ruler is not at the edge, the ruler will need to be carefully inserted into the sand until the zero mark is even with the bottom of the crater.
9. Using the same sphere, repeat steps 3–8 to obtain data for two more trials.
10. Repeat steps 3–9 using the 1.6-cm steel sphere.
11. Repeat steps 3–9 using the 1.9-cm steel sphere.

1. Level the sand in the dish as in step 1 of Part A.
2. One team member should hold the meter stick vertically so the zero end is on the work surface.
3. Another team member should hold the 1.9-cm steel sphere 30 cm above the top of the sand. Note: Be sure to measure 30 cm from the top of the sand, not from the work surface.
4. Drop the sphere onto the sand.
5. Use the two disk magnets to carefully remove the sphere from the sand, taking care to disturb the crater as little as possible.
6. Use the metric ruler to measure the diameter of the crater from the top of the “rim” on one side to the top of the “rim” straight across.
7. Record the diameter on the Investigating Impact Craters worksheet in Data Table C.
8. Use the metric ruler to measure the depth of the crater. Note: If the zero mark on the ruler is not at the edge, the ruler will need to be carefully inserted into the sand until the zero mark is even with the bottom of the crater.
9. Repeat steps 3–8 for two more trials with the same sphere.
10. Repeat steps 3–9, dropping the same sphere from 45 cm above the sand.
11. Repeat steps 3–9 dropping the same sphere from 60 cm above the sand.

Student Worksheet PDF

12379_Student1.pdf