Group Members: Jake, Blake, and Kalley
Goal: Our goal was to launch a ping pong ball the farthest distance possible using the force of a single rubber band.
Plan of Attack: Our launcher group decided to use a catapult design to launch the ball because we knew a slingshot launcher would not be very reliable. Our launcher was accurately assembled so there was little room for error. We created a base for our launcher out of wood and attached two boards to the base. Our group used one bolt to connect the launching arm to the vertical boards and another to stop the arm at an appropriate angle for the release. We attached the wooden arm to the base of the launcher using a rubber band so it would be able to load. Our group chose the thickest rubber band because it had the most tension, and we believed it would be able to emit the most force. We attached a cup to the end of the launching arm to hold the ping pong ball. Our group used an eye hook to keep the arm in place before being launched and tied a string to the hook so the arm was able to be relased. Our launcher group began building the launcher with the idea that the most affective launch angle would be forty-five degrees, but we ultimately changed the angle because our launcher was propelling the ball farther when it was released at 107 degrees. The angle varied due to our catapult design. We decided to add boards to the bottom of the base at the last minute because the ball was thrown a greater distance when it started at a higher height.
Expected Results: Our group did not know what to expect when it came to the ping pong ball launchers because we were not familiar with the project. As we started building our launcher, we struggled to work out the minor issues that were negatively affecting the launch of the ping pong ball. Fortunately we were able to limit the negative aspects of our launcher, and we expected to launch the ping pong ball about twenty-five feet.
Actual Results: On the first run, our launcher shot the ping pong ball a distance of 34 feet in 1.88 seconds. That distance was surpassed during our second run when the launcher propelled the ball 36 feet in 1.80 seconds. Our launcher released the ball at an angle of 107 degrees due to our catapult design. In order to determine the horizontal velocity, our group used the formula the change in x equals the horizotal velocity times time. We divided 11.0 by 1.80 and determined the horizontal velocity to be 6.11m/s. In order to determine the initial vertical velocity, our launcher group had to use our information about the horizontal velocity. We used the formula 6.11=zcos107 to determine the value of z as 20.9. Then our launcher group multiplied the value of z by sin107 to determine the initial vertical velocity to be 20.0 m/s.
Error Analysis: One of the major problems we experienced while building our launcher was the cup being too large for the ping pong ball. The ball was hitting the side of the cup, which caused its distance to decrease. Once we discovered this, we were able to make adjustments in order to fix the problem.
Lessons Learned: We learned that many factors go into the design of the launcher including angle of release and tension of the rubber band. We found that our catapult design shot the ball consistently at about 35 feet and launched the ball in a straight path. Our launcher group also learned how to apply the formulas we learned it the past chapter to real life.
Conclusion: Our launcher group was very happy with the results of the project. The launcher threw the ball farther than we expected. Although our launcher did not propel the ball the farthest, it was definitely the most consistent.