Physics Research Project: Final Paper

By: Mia de Haan, Ryan Hanson, Brendan O’neill, & Nick Giles

Table Of Contexts

Method | Diagram | Results Data | Table | Uncertainty | Conclusion | Return to Research


Method
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        For this experiment, we built a torsion catapult in order to see how far an object would go based on the launch angle. The materials we used were a torsion catapult, tape measure, protractor, stopwatch, baseball, golfball, and GoPro. We brought the catapult to the Tualatin High School football field where we proceeded to set it up at the zero yard line. We then set up the catapult at as close to 60° as possible. We set up a tape measure in feet along the side of the field and had a spotter to catch the landing spot of the projectiles. We also set up a GoPro so that we could take videos of each launch. For every shot we calculated the angle using a protractor app for smartphones to make sure that the angle didn’t change. The angles we tested were every 5° between 60° and 40°. Each projectile was shot three times at each angle. Our projectiles were a hard core baseball and a golf ball. In order to launch the balls, we braced the catapult, pulled back the arm as far as it would go, and released it. When the projectile was shot we had a timer start a stopwatch and when the ball hit the ground the timer stopped the stopwatch. We used the average distance and time of the three shots for each projectile at each angle and used that to calculate the velocity for each angle.

Diagram
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Results
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Calculations for velocity:

DataTable
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Baseball:

Golf Ball:

Data file: text .:. Excel

Uncertainty
Top For our uncertainty, we used the formula (High-Low)/2. So for our distance, our uncertainty was different for each set of trials at each angle. Our maximum uncertainty we calculated was +/-3.29 feet. This number was probably so large due to human error and few inconsistencies during our experiment. Our smallest uncertainty for distance was +/-0.58 feet, which was significantly smaller but was still a somewhat large number for our uncertainty.

Conclusion
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        In conclusion, our experiment supported our hypothesis. Our hypothesis stated that a catapult will launch an object the farthest when the launch angle is somewhere from 40 to 50 degrees. Any angle smaller or bigger will decrease the distance the object travels. When we launched the baseball, the maximum average distance was 18.75 feet when launch at 44.3 degrees, or approximately a 45 degree angle. Likewise, when we launched the golf ball, the maximum average distance was 31.42 feet when launched at 50.7 degrees, or approximately a 50 degree angle. Since 45-50 degrees is roughly half of a right angle, it maximized the distance or range that the balls traveled. In addition to the effect that angle has on distance, we calculated the velocity and looked at its relationship to the various angles. We noticed there was a correlation between the maximum velocities and the angle it was launched at. From that we were able to conclude that approximately 40-50 degrees angles are also optimal for velocity. Overall, our experiment allowed us to support our hypothesis and prove that anywhere from a 40-50 degree launch angle allows for an optimal distance and velocity.

Throughout our experiment we encountered a few limitations and inconsistencies. First of all, the arm of our catapult didn’t always launch in a perfectly straight line. Because of that, it would cause the ball to sway left to right in the air and ultimately land at a shorter distance. Another limitation we encountered was that the bottom of the catapult arm would scrape against the ground with each launch, limiting the distance on each throw. Our biggest limitation though would be human error. As the objects were thrown, a person would be the judge of where it landed and at what time. Lacking in the necessary resources to brace our catapult at the time of gathering our data, a person would have to sit in the catapult in order to make sure the catapult would stay grounded. Further, having to move to angle with which the arm stopped required a constant, and not altogether perfect adjustment of the desired angles. To further our research, we might look into how the amount of torsion effects the distance, in addition to the various angles. We could find a way to calculate how many revolutions of torsion affect the potential energy and how that can affect the distance and velocity.

Related Websites:

Wikipedia: We enjoyed the basic facts Wikipedia gained

Make your own! or Watch a Video: We used this as a guide to our catapult

SCIENCE!: Explained how a Mangonel catapult works

MORE SCIENCE!: The More You Know *rainbow appears with a whooshing noise*

Trebuchets: Trebuchets, because you know, why not?

Trebuchets 2: Our initial plan was Trebs, but Mangonel was actually feasible