# Investigating Impact Craters

Extracts from this document...

Introduction

Philip Jenkins

Physics Investigation

Investigating Impact Craters

The Aim of this investigation is to determine relationships between the following variables:

- The height from which a ball (a simple model of an asteroid or meteor) is dropped and the diameter of its impact crater.

- The height from which a ball is dropped and the depth of its impact crater.

- The diameter of a ball and its impact crater.

- The mass of a ball and the diameter of its impact crater.

- The mass of a ball and the depth of its impact crater.

- The angle at which the ball impacts and the length of its impact crater.

- The angle at which a ball impacts and the depth of its impact crater.

- Keeping the angle the same, changing the magnitude of the ball’s velocity – and measure the length and depth of impact craters.

- Changing the vertical height dropped by the ball, after being released at an angle.

## Preliminary Experiments

In order to get the best range of results some preliminary work was required. Firstly the material which was to be dropped into needed to be decided upon. The three main options are as follows:

- Flour

This was initially intended as the impact material, however after some early tests it was found that the flour would not hold its shape correctly after the ball had been removed from the impact crater. This lead to the diameter of the craters being changed greatly from the expected values.

- Salt

Middle

The ball was dropped from an ample height of 35cm with 4 different masses. Each mass was dropped 5 times and an average taken for the crater diameter and depth (to the nearest millimetre).

Mass of Ball (g) | Crater Diameter (mm) | Crater Depth (mm) |

10 | 17 | 2 |

20 | 19 | 4 |

30 | 23 | 6 |

40 | 24 | 7 |

See overleaf for graph.

## Graph Analysis

This graph is very pleasing, as both the crater diameter and depth appear to have good linear relationships with the mass of the ball.

This will be due to the ball having more kinetic energy (mass multiplied by velocity squared) – so more energy will be put into displacing the sand grains downward and outward.

## Experiment Three – How does crater diameter vary with the ball’s diameter?

Balls of similar mass and varying diameters were chosen for this experiment. Again the drop height was kept constant at 35cm and the balls were dropped 3 times.

Ball diameter (mm) | Crater diameter (mm) |

53 | 42 |

47 | 34 |

43 | 25 |

32 | 21 |

21 | 20 |

16 | 16 |

Graph Analysis

Another linear relationship – this time it is looser though. This could be due to the masses of the balls being slightly different. It was very difficult to find balls with similar masses – it would have been near impossible to find so many balls with identical masses.

Again the graph produces no surprises, as you would expect a ball with a larger diameter to produce a larger crater. The linear relationship would suggest that there is a constant that could be found and applied to balls of any diameter.

Angular Craters

Conclusion

Conclusions and Evaluation

The following relationships were found:

- For vertical drops, the drop height, ball mass and ball diameter all have a linear relationship with the resulting crater’s diameter and depth.

- The angle at which a ball enters the sand is exponentially linked with the length of the crater produced (for angles above 25 deg.).

- The angle at which a ball impacts is proportionally linked to the depth of the impact crater.

- The speed of impact has no discernible effect on the depth of the crater (at low speeds at least).

- The vertical height dropped has a linear relationship with the horz distance travelled.

On the whole, the experiment was a success, however there are a few problems which would be solved if the experiments were to be repeated.

Firstly, for the final experiment, the landing tray was not long enough to slow down balls travelling at high speed. A longer tray would have been able to produce a wider range of results.

Also the sand was difficult to keep perfectly level, and its compactness was hard to measure/control. This could have lead to some inaccurate results, as sometimes the ball would simply sink into the sand, but on other occasions it would roll across the top – giving a much larger distance. Possibly a rake or a large flat object could have been used to level the sand and break up any clumps.

This student written piece of work is one of many that can be found in our GCSE Forces and Motion section.

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