Lacrosse Craters of Death!!!!!

Introduction:  Top

Many people think about energy, and they think about the laws of motion. The laws of motion were created by Sir Isaac Newton and have governed our world for many years now. The laws of motion are enacted on this project as gravity pulls the ball upon the sand. The thought of gravity and falling then leads people to think about energy, both potential and kinetic. There is a large amount of potential energy at the drop height because gravity is pulling it down. However, there is also a large sum of kinetic energy as the lacrosse ball is released and falls upon the sand below it. This then leads thoughts to the energy that was created by the drop, and the work that was done on the sand by the impact of the ball.

For the course of the experiment, sand was acquired from the Oregon coast to drop things on. Lacrosse balls were brought in from the Stone household that were gifts from Mr. George Holomon in the athletic training room. For the record, lacrosse balls weigh between 140g and 147g and are 45% rubber. The drop heights are determined by a 25 tape measure placed upon the sand in the bucket. A ruler and a shish kabob are used to find the crater depth by finding the difference of the depth of the sand before and after impact.

The purpose of this experiment is to find the relation between the height a lacrosse ball is dropped from and the impression the ball creates in the sand from the drop.

When a lacrosse ball is dropped from increasing heights, the hole in the sand caused by the ball will become increasingly larger. The measurement of the indent will be determined from the depth of the sand at the deepest point of the hole. The dependent variables are the height of the drop, the amount and depth of the sand, and gravity. The independent variables include the temperature and sand condition.

Hypothesis: Top

If the drop height of a lacrosse ball increases then the crater depth will also increase because the ball has more time to accelerate.

We hypothesized that this would happen because of our basic knowledge of falling objects and forces of impact.

Method: Top

We started by pouring dry sand into a rectangle bucket then flattening it out, without compacting it. Then we measure the sand by placing a thin wooden dowel through the sand till it reached the bottom. We marked the dowel where the sand ended and pulled it out to measure it with a ruler, this measurement was our before number. Then we measured out the drop height with a tape measure and dropped the lacrosse ball into the bucket of sand where we had done the before measurement. Next we carefully removed the ball and re-measured the sand from the deepest point in the crater. We then subtracted the new number from our before drop number to get the crater depth. We repeated this until we had six trials for each of the nine drop heights.

Diagram: Top

List of Materials:  Top

        Bucket

        Dry sand from Oregon Coast

        Ruler

        Tape measurer

        Lacrosse ball

        Thin wooden dowel

Data: Top

 Drop Height in cm (+ or - 0.5 cm) Average Crater Depth in cm (+ or - 0.5 cm) 15.24 1.11 30.48 1.13 45.72 1.40 60.96 2.16 76.20 2.22 91.44 2.31 106.68 2.35 121.92 2.46

 .5 Foot drop height Crater depth (in cm) Average crater depth (in cm) Trial 1 1.3 Trial 2 0.9 Trial 3 1 Trial 4 1.5 Trial 5 1 Trial 6 1 1.11 1 foot drop height Crater depth (in cm) Average crater depth (in cm) Trial 1 1.4 Trial 2 0.8 Trial 3 2.4 Trial 4 2.2 Trial 5 0.8 Trial 6 1.3 1.13 1.5 foot drop height Crater depth (in cm) Average crater depth (in cm) Trial 1 2 Trial 2 1.5 Trial 3 1.5 Trial 4 1.2 Trial 5 1.2 Trial 6 1 1.4 2 foot drop height Crater depth (in cm) Average crater depth (in cm) Trial 1 2.7 Trial 2 1.9 Trial 3 2.2 Trial 4 1.9 Trial 5 2.3 Trial 6 2 2.16 2.5 foot drop Crater depth (in cm) Average crater depth (in cm) Trial 1 2.5 Trial 2 1.9 Trial 3 1.9 Trial 4 2.2 Trial 5 2.3 Trial 6 2.5 2.22 3 Foot drop height Crater depth (in cm) Average crater depth (in cm) Trial 1 2.2 Trial 2 2.5 Trial 3 2.5 Trial 4 2.1 Trial 5 2.4 Trial 6 2.2 2.31 3.5 foot drop height Crater depth (in cm) Average crater depth (in cm) Trial 1 2.8 Trial 2 2.3 Trial 3 2.1 Trial 4 2.1 Trial 5 2.4 Trial 6 2.4 2.35 4 foot drop height Crater depth (in cm) Average crater depth (in cm) Trial 1 1.9 Trial 2 2.4 Trial 3 2.1 Trial 4 2.5 Trial 5 3.1 Trial 6 2.8 2.46

Results: Top

Basics calculation formula:             Before  after = Crater depth

All Crater depths/6 = average crater depth

We found that as the drop height increased, so did the average crater depth. We found that even though the drop height increase was consistent, the crater depth change was not. There was also a wide range in crater depth results for each drop height, sometimes up to an entire cm difference from the deepest to the shallowest.

Conclusion: Top

In conclusion we found that as we increased the height of the lacrosse ball, the average crater depth also increased. This data correlates with our hypothesis that the higher an object is dropped, the deeper the crater is. The reason our data turned out like this is because as the height gets greater the potential energy increases which leads to the kinetic energy increasing. This fact is shown by the work done by the sand in the depth of the crater. Our main source of error was human error. We had a person dropping the ball into the sand. Therefore, the exact drop height was not as accurate as it could have been if a machine dropped the ball. In the future, we could improve our procedure by recording our experiment and using logger pro to determine the celocity and time of each drop. On top of that we could do more trials and more variations o help get a more conclusive sample size. We could also have a machine drop the ball so that the human error is reduced.

Bibliography: Top

Gravity-

http://en.wikipedia.org/wiki/Gravitation

•          Explains the gravitational pull that controls the force on Earth

Impact Craters-

http://www.nature.com/nphys/journal/v3/n6/full/nphys583.html

•         Describes the creation of craters

Lacrosse Ball-

http://www.hautestick.com/LaxGear/OddBall/NCAA-Spec-Ball.html

•         Provides all information regarding the Lacrosse ball

Laws of Motion-

http://csep10.phys.utk.edu/astr161/lect/history/newton3laws.html

•         Explains why the Laws of Gravity that force the ball to fall

•         Explains how our experiment is relevant

Sand-

http://www.mrsciguy.com/weathering.html

•         Look at the wind section

•         Explains the creation of sand